TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 FULLY INTEGRATED 13.56-MHz RFID READER/WRITER IC FOR ISO15693/ISO18000-3 STANDARDS Check for Samples: TRF7962A 1 Introduction 1.1 Features 123 * Completely Integrated Protocol Handling for ISO15693 and ISO18000-3 * Input Voltage Range: 2.7 VDC to 5.5 VDC * Programmable Output Power: +20 dBm (100 mW) or +23 dBm (200 mW) * Programmable I/O Voltage Levels: 1.8 VDC to 5.5 VDC * Programmable System Clock Frequency Output (RF, RF/2, RF/4) * Programmable Modulation Depth 1.2 * * * * * * * Dual Receiver Architecture With RSSI for Elimination of "Read Holes" and Adjacent Reader System/Ambient In-Band Noise Detection * Programmable Power Modes for Ultra-Low Power System Design (Power Down <0.5 A) * Parallel or SPI Interface * Integrated Voltage Regulator for Microcontroller Supply * Temperature Range: -25C to 85C * 32-Pin QFN Package (5 mm x 5 mm) (RHB) Applications Product Authentication Access Control Digital Door Lock Library Management Medical Systems Remote Sensor Applications 1.3 Description The TRF7962A is an integrated analog front end and data-framing device for a 13.56-MHz RFID reader/writer system. Built-in programming options make it suitable for a wide range of applications for vicinity identification systems. The reader is configured by selecting the desired protocol in the control registers. Direct access to all control registers allows fine tuning of various reader parameters as needed. Comprehensive documentation, reference designs, evaluation modules, and TI microcontrollers (based on MSP430TM or ARMTM technology) source code are available. The TRF7962A is a high-performance 13.56-MHz HF RFID reader IC comprising an integrated analog front end (AFE) and a built-in data framing engine for ISO15693 with all framing and synchronization tasks on board (in ISO Mode, default). This architecture enables the customer to build a complete and costeffective yet high-performance HF RFID reader/writer using a low-cost microcontroller (for example, an MSP430). Other standards and even custom protocols can be implemented by using two of the Direct Modes the device offers. These Direct Modes (0 and 1) allow the user to fully control the analog front end (AFE) and also gain access to the raw subcarrier data or the unframed, but already ISO formatted data and the associated (extracted) clock signal. 1 2 3 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. MSP430 is a trademark of Texas Instruments. ARM is a trademark of ARM Limited. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 2011-2012, Texas Instruments Incorporated TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com VDD _I/O MUX RX_IN1 RX_IN2 Phase and Amplitude Detector RSSI (AUX) RSSI (External) Phase and Amplitude Detector VDD_PA TX_ OUT Gain Transmitter Analog Front End Gain RSSI (Main) Filter, AGC Digitizer ISO Protocol Handling Decoder Framing Bit Framing Logic I/O_0 State Control Logic (Control Registers, Command Logic) I/O_1 ASK/ OOK 12-Byte FIFO I/O_5 I/O_7 SYS _CLK DATA _CLK VDD _A BAND _GAP VSS _A VDD _RF Voltage Supply Regulator Systems (Supply Regulators, Reference Voltages) OSC_IN Level Shifter VIN Digital Control State Machine MOD OSC_ OUT I/O_4 IRQ EN EN2 I/O_3 I/O_6 MCU Interface Serial Conversion CRC, Parity VSS_PA I/O_2 VSS _RF VDD_X VSS Crystal Oscillator Timing System VSS _D Figure 1-1. Block Diagram The receiver system has a dual-input receiver architecture. The receivers also include various automatic and manual gain control options. The received input bandwidth can be selected to cover a broad range of input subcarrier signal options. The received signal strength from transponders, ambient sources or internal levels is available via the RSSI register. The receiver output is selectable among a digitized subcarrier signal and any of the integrated subcarrier decoders. The selected subcarrier decoder delivers the data bit stream and the data clock as outputs. The TRF7962A includes a receiver framing engine. This receiver framing engine performs the CRC and/or parity check, removes the EOF and SOF settings, and organizes the data in bytes for the ISO15693 protocol. Framed data is then accessible to the microcontroller (MCU) via a 12-byte FIFO register. A parallel or serial interface (SPI) can be used for the communication between the MCU and the TRF7962A reader. When the built-in hardware encoders and decoders are used, transmit and receive functions use a 12-byte FIFO register. For direct transmit or receive functions, the encoders or decoders can be bypassed so the MCU can process the data in real time. The TRF7962A supports data communication levels from 1.8 V to 5.5 V for the MCU I/O interface. The transmitter has selectable output power levels of 100 mW (+20 dBm) or 200 mW (+23 dBm) equivalent into a 50- load when using a 5-V supply. 2 Introduction Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 VDD VDD_X VDD_I/O VDD TX_OUT Matching MCU (MSP430/ARM) Parallel or SPI TRF796xA RX_IN 1 RX_IN 2 VSS Crystal 13.56 MHz VIN XIN Supply 2.7 V to 5.5 V Figure 1-2. Application Block Diagram The transmitter supports OOK and ASK modulation with selectable modulation depth. The TRF7962A includes a data transmission engine that supports low-level encoding for ISO15693. Included with the transmit data coding is the automatic generation of Start Of Frame (SOF), End Of Frame (EOF), Cyclic Redundancy Check (CRC), and parity bits. Several integrated voltage regulators ensure a proper powersupply noise rejection for the complete reader system. The built-in programmable auxiliary voltage regulator VDD_X (pin 32) delivers up to 20 mA to supply a microcontroller and additional external circuits within the reader system. Table 1-1. Supported Protocols Supported Protocols Device TRF7962A 1.4 TRF7962ARHBT TRF7962ARHBR (2) ISO18000-3 Mode 1 Ordering Information Packaged Devices (1) (1) ISO15693 Package Type (2) Transport Media RHB-32 Tape and Reel Quantity 250 3000 For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI Web site at www.ti.com. Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at www.ti.com/sc/package. Introduction Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 3 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 1 2 3 4 .............................................. ............................................. 1.2 Applications .......................................... 1.3 Description ........................................... 1.4 Ordering Information ................................. Physical Characteristics ............................... 2.1 Device Pinout ........................................ 2.2 Terminal Functions .................................. Electrical Characteristics .............................. 3.1 Absolute Maximum Ratings .......................... 3.2 Dissipation Ratings .................................. 3.3 Recommended Operating Conditions ............... 3.4 Electrical Characteristics ............................ 3.5 Switching Characteristics ............................ Introduction 1 5.1 1.1 1 5.2 1 5.3 1 5.4 3 5.5 5 5.6 5 5.7 5 5.8 7 5.9 7 5.10 5.11 4.2 4 Features 7 7 8 9 Application Schematic and Layout Considerations ......................................... 10 4.1 5 www.ti.com TRF7962A Reader System Using Parallel Microcontroller Interface ............................ 10 TRF7962A Reader System Using SPI With SS Mode ................................................ 11 Detailed System Description ........................ 12 ............................. ..................................... Supply Arrangements .............................. Supply Regulator Settings .......................... Power Modes ....................................... Receiver - Analog Section .......................... Receiver - Digital Section ........................... Oscillator Section ................................... Transmitter - Analog Section ....................... Transmitter - Digital Section ........................ System Block Diagram Power Supplies 12 12 12 14 15 17 18 21 22 23 Transmitter - External Power Amplifier / Subcarrier detector ............................................. 23 ............... ........... 6 Register Description .................................. 6.1 Register Overview .................................. 7 System Design ......................................... 7.1 Layout Considerations .............................. 7.2 Impedance Matching TX_Out (Pin 5) to 50 ...... 7.3 Reader Antenna Design Guidelines ................ Revision History ............................................ 5.12 TRF7962A Communication Interface 23 5.13 Direct Commands from MCU to Reader 40 Contents 43 43 57 57 57 58 59 Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 2 Physical Characteristics 2.1 Device Pinout VDD_X OSC_IN OSC_OUT VSS_D EN SYS_CLK DATA_CLK EN2 RHB PACKAGE (TOP VIEW) 1 32 31 30 29 28 27 26 25 24 2 3 23 22 4 5 6 21 Thermal Pad (Connect to Ground) 20 19 7 18 8 17 9 10 11 12 13 14 15 16 I/O_7 I/O_6 I/O_5 I/O_4 I/O_3 I/O_2 I/O_1 I/O_0 RX_IN2 VSS BG ASK/OOK IRQ MOD VSS_A VDD_I/O VDD_A VIN VDD_RF VDD_PA TX_OUT VSS_PA VSS_RX RX_IN1 Figure 2-1. TRF7962A Pin Assignment 2.2 Terminal Functions Table 2-1. Terminal Functions Terminal Name No. VDD_A 1 VIN VDD_RF Type (1) Description OUT Internal regulated supply (2.7 V to 3.4 V) for analog circuitry 2 SUP External supply input to chip (2.7 V to 5.5 V) 3 OUT Internal regulated supply (2.7 V to 5 V); normally connected to VDD_PA (pin 4) VDD_PA 4 INP Supply for PA; normally connected externally to VDD_RF (pin 3) TX_OUT 5 OUT RF output (selectable output power: 100 mW or 200 mW, with VDD = 5 V) VSS_PA 6 SUP Negative supply for PA; normally connected to circuit ground VSS_RX 7 SUP Negative supply for receive inputs; normally connected to circuit ground RX_IN1 8 INP Main receive input RX_IN2 9 INP Auxiliary receive input VSS 10 SUP Chip substrate ground BAND_GAP 11 OUT Bandgap voltage (VBG = 1.6 V); internal analog voltage reference ASK/OOK 12 BID IRQ 13 OUT Interrupt request MOD 14 VSS_A VDD_I/O Selection between ASK and OOK modulation (0 = ASK, 1 = OOK) for Direct Mode 0 and 1. It can be configured as an output to provide the received analog signal output. (1) INP External data modulation input for Direct Mode 0 or 1 OUT Subcarrier digital data output (see register 0x1A and 0x1B definitions) 15 SUP Negative supply for internal analog circuits; connected to GND 16 INP Supply for I/O communications (1.8 V to VIN) level shifter. VIN should be never exceeded. SUP = Supply, INP = Input, BID = Bidirectional, OUT = Output Physical Characteristics Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 5 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com Table 2-1. Terminal Functions (continued) Terminal Name No. Type (1) Description I/O_0 17 BID I/O pin for parallel communication I/O_1 18 BID I/O pin for parallel communication I/O_2 19 BID I/O pin for parallel communication I/O_3 20 BID I/O pin for parallel communication I/O_4 21 BID I/O pin for parallel communication Slave select signal in SPI mode I/O_5 22 BID I/O pin for parallel communication Data clock output in Direct Mode 1 I/O pin for parallel communication I/O_6 23 BID MISO for serial communication (SPI) Serial bit data output in Direct Mode 1 or subcarrier signal in Direct Mode 0 I/O_7 24 BID I/O pin for parallel communication. MOSI for serial communication (SPI) EN2 25 INP Selection of power down mode. If EN2 is connected to VIN, then VDD_X is active during power down mode 2 (for example, to supply the MCU). DATA_CLK 26 INP Data clock input for MCU communication (parallel and serial) SYS_CLK 27 OUT If EN = 1 (EN2 = don't care) the system clock for the MCU is configured with register 0x09 (off, 3.39 MHz, 6.78 MHz, or 13.56 MHz). If EN = 0 and EN2 = 1, the system clock is set to 60 kHz EN 28 INP Chip enable input (If EN = 0, then the chip is in sleep or power-down mode) VSS_D 29 SUP Negative supply for internal digital circuits OSC_OUT 30 OUT Crystal or oscillator output OSC_IN 31 INP Crystal or oscillator input VDD_X 32 OUT Internally regulated supply (2.7 V to 3.4 V) for digital circuit and external devices (for example, an MCU) PAD SUP Chip substrate ground PAD 6 Physical Characteristics Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 3 Electrical Characteristics 3.1 Absolute Maximum Ratings (1) over operating free-air temperature range (unless otherwise noted) VIN Input voltage range IIN Maximum current ESD Electrostatic discharge rating (2) -0.3 V to 6 V 150 mA Human-body model (HBM) 2 kV Charged-device model (CDM) TJ Maximum operating virtual junction temperature TSTG (1) (2) (3) 3.2 (1) (2) 3.3 (3) 500 V Machine model (MM) 200 V Any condition 140C Continuous operation, long-term reliability 125C Storage temperature range 300C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under Operating Conditions are not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltage values are with respect to substrate ground terminal VSS. The maximum junction temperature for continuous operation is limited by package constraints. Operation above this temperature may result in reduced reliability and/or lifetime of the device. Dissipation Ratings PACKAGE JC JC (1) RHB (32) 31C/W 36.4C/W POWER RATING (2) TA 25C TA 85C 2.7 W 1.1 W This data was taken using the JEDEC standard high-K test PCB. Power rating is determined with a junction temperature of 125C. This is the point where distortion starts to increase substantially. Thermal management of the final PCB should strive to keep the junction temperature at or below 125C for best performance and longterm reliability. Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN TYP MAX VIN Operating input voltage 2.7 5 5.5 V TA Operating ambient temperature -25 25 85 C TJ Operating virtual junction temperature -25 25 125 C Electrical Characteristics Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A UNIT 7 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 3.4 www.ti.com Electrical Characteristics TA = 25C, VIN = 5 V, full-power mode (unless otherwise noted) PARAMETER CONDITIONS MIN TYP MAX UNIT IPD1 Supply current in Power Down Mode 1 All building blocks disabled, including supplyvoltage regulators; measured after 500-ms settling time (EN = 0, EN2 = 0) <0.5 5 A IPD2 Supply current in Power Down Mode 2 (Sleep Mode) The SYS_CLK generator and VDD_X remain active to support external circuitry, measured after 100-ms settling time (EN = 0, EN2 = 1) 120 200 A ISTBY Supply current in stand-by mode Oscillator running, supply-voltage regulators in low-consumption mode (EN = 1, EN2 = x) 1.9 3.5 mA ION1 Supply current without antenna driver current Oscillator, regulators, RX, and AGC are active, TX is off 10.5 14 mA ION2 Supply current - TX (half power) Oscillator, regulators, RX, AGC, and TX active, POUT = 100 mW 70 78 mA ION3 Supply current - TX (full power) Oscillator, regulators, RX, AGC, and TX active, POUT = 200 mW 130 170 mA VPOR Power-on reset voltage Input voltage at VIN 1.4 2 2.6 V VBG Bandgap voltage (pin 11) Internal analog reference voltage 1.5 1.6 1.7 V VDD_A Regulated output voltage for analog circuitry (pin 1) VIN = 5 V 3.1 3.5 3.8 V VDD_X Regulated supply for external circuitry Output voltage pin 32, VIN = 5 V 3.1 3.4 3.8 V IVDD_Xmax Maximum output current of VDD_X Output current pin 32, VIN = 5 V (1) 20 mA Half power mode, VIN = 2.7 V to 5.5 V 8 12 Full power mode, VIN = 2.7 V to 5.5 V 4 6 10 20 k RRFOUT Antenna driver output resistance RRFIN RX_IN1 and RX_IN2 input resistance VRF_INmax Maximum RF input voltage at RX_IN1, RX_IN2 VRF_INmax should not exceed VIN 3.5 VRF_INmin Minimum RF input voltage at RX_IN1, RX_IN2 (input sensitivity) (2) fSUBCARRIER = 424 kHz 1.4 fSYS_CLK SYS_CLK frequency In power mode 2, EN = 0, EN2 = 1 fC Carrier frequency Defined by external crystal tCRYSTAL Crystal run-in time Time until oscillator stable bit is set (register 0x0F) (3) fD_CLKmax Maximum DATA_CLK frequency VIL Input voltage, logic low I/O lines, IRQ, SYS_CLK, DATA_CLK, EN, EN2 0.2 x VDD_I/O V VIH Input voltage threshold, logic high I/O lines, IRQ, SYS_CLK, DATA_CLK, EN, EN2 0.8 x VDD_I/O V ROUT Output resistance, I/O_0 to I/O_7 500 800 RSYS_CLK Output resistance RSYS_CLK 200 400 4 fSUBCARRIER = 848 kHz (1) (2) (3) (4) 8 (4) 25 Vpp 2.5 mVpp 2.1 3 mVpp 60 120 13.56 Depends on capacitive load on the I/O lines, recommendation is 2 MHz (4) MHz 5 2 8 kHz ms 10 MHz Antenna driver output resistance Measured with subcarrier signal at RX_IN1/2 and measured the digital output at MOD pin with register 0x1A bit 6 = 1 Depending on the crystal parameters and components Recommended DATA_CLK speed is 2 MHz; higher data clock depends on the capacitive load. Maximum SPI clock speed should not exceed 10 MHz. This clock speed is acceptable only when external capacitive load is less than 30 pF. MISO driver has a typical output resistance of 400 (12-ns time constant when 30-pF load is used). Electrical Characteristics Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com 3.5 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Switching Characteristics over operating free-air temperature range (unless otherwise noted) PARAMETER CONDITIONS MIN TYP MAX UNIT 50 62.5 250 ns tLO/HI DATA_CLK time, high or low (one half Depends on capacitive load on the I/O lines of DATA_CLK at 50% duty cycle) tSTE,LEAD Slave select lead time, slave select low to clock 200 ns tSTE,LAG Slave select lag time, last clock to slave select high 200 ns tSU,SI MOSI input data setup time 15 ns tHD,SI MOSI input data hold time 15 ns tSU,SO MISO input data setup time 15 ns tHD,SO MISO input data hold time 15 tVALID,SO MISO output data valid time (1) (1) DATA_CLK edge to MISO valid, CL = <30 pF 30 ns 50 75 ns Recommended DATA_CLK speed is 2 MHz; higher data clock depends on the capacitive load. Maximum SPI clock speed should not exceed 10 MHz. This clock speed is acceptable only when external capacitive load is less than 30 pF. MISO driver has a typical output resistance of 400 (12-ns time constant when 30-pF load is used). Electrical Characteristics Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 9 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com 4 Application Schematic and Layout Considerations 4.1 4.1.1 TRF7962A Reader System Using Parallel Microcontroller Interface General Application Considerations Figure 4-1 shows the most flexible TRF7962A application. Due to the low clock frequency on the DATA_CLK line, the parallel interface is the most robust way to connect the TRF7962A with the MCU. This schematic shows matching to a 50- port, which allows connection to a properly matched 50- antenna circuit or RF measurement equipment (for example, a spectrum analyzer or power meter). 4.1.2 Schematic Figure 4-1 shows a sample application schematic with a parallel interface to the MCU. Figure 4-1. Application Schematic, Parallel MCU Interface The MSP430F2370 (32kB flash, 2kB RAM) is shown in Figure 4-1. Minimum MCU requirements depend on application requirements and coding style. If only one ISO protocol and/or a limited command set of a protocol must be supported, MCU flash and RAM requirements can be significantly reduced. Note that recursive inventory and anticollision commands require more RAM than single slotted operations. For example, current reference firmware for ISO15693 (with host interface) is approximately 8kB, using 512B RAM. 10 Application Schematic and Layout Considerations Submit Documentation Feedback Product Folder Link(s): TRF7962A Copyright (c) 2011-2012, Texas Instruments Incorporated TRF7962A www.ti.com 4.2 4.2.1 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 TRF7962A Reader System Using SPI With SS Mode General Application Considerations Figure 4-2 shows the TRF7962A application schematic using the Serial Port Interface (SPI). Short SPI lines, proper isolation to radio frequency lines, and a proper ground area are essential to avoid interference. The recommended clock frequency on the DATA_CLK line is 2 MHz. This schematic shows matching to a 50- port, which allows connection to a properly matched 50- antenna circuit or RF measurement equipment (for example, a spectrum analyzer or power meter). 4.2.2 Schematic Figure 4-2 shows a sample application schematic with a serial interface to the MCU. Figure 4-2. Application Schematic, SPI With SS Mode MCU Interface The MSP430F2370 (32kB flash, 2kB RAM) is shown in Figure 4-2. Minimum MCU requirements depend on application requirements and coding style. If only one ISO protocol and/or a limited command set of a protocol must be supported, MCU flash and RAM requirements can be significantly reduced and user should be aware that recursive inventory/anticollision commands require more RAM than single slotted operations. For example, current reference firmware for ISO15693 (with host interface) is approximately 8kB, using 512B RAM. Copyright (c) 2011-2012, Texas Instruments Incorporated Application Schematic and Layout Considerations Submit Documentation Feedback Product Folder Link(s): TRF7962A 11 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com 5 Detailed System Description 5.1 System Block Diagram VDD _I/O MUX RX_IN1 Phase and Amplitude Detector RSSI (AUX) RSSI (External) RX_IN2 Phase and Amplitude Detector VDD_PA TX_ OUT Gain Transmitter Analog Front End Gain RSSI (Main) Filter, AGC Digitizer ISO Protocol Handling Decoder Bit Framing Framing Logic I/O_0 State Control Logic (Control Registers, Command Logic) I/O_1 I/O_5 I/O_7 12-Byte FIFO SYS _CLK DATA _CLK VIN VDD _A BAND _GAP VSS _A EN2 Digital Control State Machine ASK/ OOK MOD VDD _RF Voltage Supply Regulator Systems (Supply Regulators, Reference Voltages) OSC_ OUT I/O_4 Level Shifter IRQ EN OSC_IN I/O_3 I/O_6 MCU Interface Serial Conversion CRC, Parity VSS_PA I/O_2 VSS _RF VDD_X VSS Crystal Oscillator Timing System VSS _D Figure 5-1. System Block Diagram 5.2 Power Supplies The TRF7962A positive supply input VIN (pin 2) sources three internal regulators with output voltages VDD_RF, VDD_A, and VDD_X. All regulators require external bypass capacitors for supply noise filtering and must be connected as indicated in reference schematics. These regulators provide a high power supply reject ratio (PSRR) as required for RFID reader systems. All regulators are supplied via VIN (pin 2). The regulators are not independent and have common control bits in register 0x0B for output voltage setting. The regulators can be configured to operate in either automatic or manual mode (register 0x0B, bit 7). The automatic regulator setting mode ensures an optimal compromise between PSRR and the highest possible supply voltage for RF output (to ensure maximum RF power output). The manual mode allows the user to manually configure the regulator settings. 5.3 Supply Arrangements Regulator Supply Input: VIN The positive supply at VIN (pin 2) has an input voltage range of 2.7 V to 5.5 V. VIN provides the supply input sources for three internal regulators with the output voltages VDD_RF, VDD_A, and VDD_X. External bypass capacitors for supply noise filtering must be used (per reference schematics). NOTE VIN must be the highest voltage supplied to the TRF7962A. 12 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 RF Power Amplifier Regulator: VDD_RF The VDD_RF (pin 3) regulator is supplying the RF power amplifier. The voltage regulator can be set for either 5V or 3V operation. External bypass capacitors for supply noise filtering must be used (per reference schematics). When configured for 5V manual-operation, the VDD_RF output voltage can be set from 4.3 V to 5 V in 100-mV steps. In 3-V manual operation, the output can be programmed from 2.7 V to 3.4 V in 100-mV steps (see Table 5-2). The maximum output current capability for 5-V operation is 150 mA and for 3-V operation is 100 mA. Analog Supply Regulator: VDD_A Regulator VDD_A (pin 1) supplies the analog circuits of the device. The output voltage setting depends on the input voltage and can be set for 5-V and 3-V operation. When configured for 5-V manual operation, the output voltage is fixed at 3.4 V. External bypass capacitors for supply noise filtering must be used (per reference schematics). When configured for 3-V manual operation, the VDD_A output can be set from 2.7 V to 3.4 V in 100-mV steps (see Table 5-2). NOTE The configuration of VDD_A and VDD_X regulators are not independent from each other. The VDD_A output current should not exceed 20 mA. Digital Supply Regulator: VDD_X The Digital Supply Regulator VDD_X (pin 32) provides the power for the internal digital building blocks and can also be used to supply external electronics within the reader system. When configured for 3-V operation, the output voltage can be set from 2.7 to 3.4 V in 100-mV steps. External bypass capacitors for supply noise filtering must be used (per reference schematics). NOTE The configuration of the VDD_A and VDD_X regulators are not independent from each other. The VDD_X output current should not exceed 20 mA. The RF power amplifier regulator (VDD_RF), analog supply regulator (VDD_A), and digital supply regulator (VDD_X) can be configured to operate in either automatic or manual mode described in Table 51. The automatic regulator setting mode ensures an optimal compromise between PSRR and the highest possible supply voltage to ensure maximum RF power output. By default, the regulators are set in automatic regulator setting mode. In this mode, the regulators are automatically set every time the system is activated by setting EN input High or each time the automatic regulator setting bit, B7 in register 0x0B is set to a 1. The action is started on the 0 to 1 transition. This means that, if the user wants to re-run the automatic setting from a state in which the automatic setting bit is already high, the automatic setting bit (B7 in register 0x0B) should be changed: 1-0-1. By default, the regulator setting algorithm sets the regulator outputs to a "Delta Voltage" of 250 mV below VIN, but not higher than 5 V for VDD_RF and 3.4 V for VDD_A and VDD_A. The "Delta Voltage" in automatic regulator mode can be increased up to 400 mV (for more details, see bits B0 to B2 in register 0x0B). Power Amplifier Supply: VDD_PA The power amplifier of the TRF7962A is supplied through VDD_PA (pin 4). The positive supply pin for the RF power amplifier is externally connected to the regulator output VDD_RF (pin 3). Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 13 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com I/O Level Shifter Supply: VDD_I/O The TRF7962A has a separate supply input VDD_I/O (pin 16) for the build in I/O level shifter. The supported input voltage ranges from 1.8 V to VIN, however not exceeding 5.5 V. Pin 16 is used to supply the I/O interface pins (I/O_0 to I/O_7), IRQ, SYS_CLK, and DATA_CLK pins of the reader. In typical applications, VDD_I/O is directly connected to VDD_X while VDD_X also supplies the MCU. This ensures that the I/O signal levels of the MCU match with the logic levels of the TRF7962A. Negative Supply Connections: VSS, VSS_RX, VSS_A, VSS_PA The negative supply connections VSS_X of each functional block are all externally connected to GND. The substrate connection is VSS (pin 10), the analog negative supply is VSS_A (pin 15), the logic negative supply is VSS_D (pin 29), the RF output stage negative supply is VSS_PA (pin 6), and the negative supply for the RF receiver VSS_RX (pin 7). 5.4 Supply Regulator Settings The input supply voltage mode of the reader must be selected. This is done in the Chip Status Control register (0x00). Bit 0 in register 0x00 selects between 5-V or 3-V input supply voltage. The default configuration is 5 V, which reflects an operating supply voltage range of 4.3 V to 5.5 V. If the supply voltage is below 4.3 V, the 3-V configuration should be used. The various regulators can be configured to operate in automatic or manual mode. This is done in the Regulator and I/O Control register (0x0B) as shown in Table 5-1. Table 5-1. Supply Regulator Setting: 5-V System Register Address Option Bits Setting in Regulator Control Register (1) B7 B6 B5 B4 B3 B2 B1 B0 Comments Automatic Mode (default) 0B 1 x x x x x 1 1 Automatic regulator setting 250-mV difference 0B 1 x x x x x 1 0 Automatic regulator setting 350-mV difference 0B 1 x x x x x 0 0 Automatic regulator setting 400-mV difference 0B 0 x x x x 1 1 1 VDD_RF = 5 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 1 1 0 VDD_RF = 4.9 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 1 0 1 VDD_RF = 4.8 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 1 0 0 VDD_RF = 4.7 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 0 1 1 VDD_RF = 4.6 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 0 1 0 VDD_RF = 4.5 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 0 0 1 VDD_RF = 4.4 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 0 0 0 VDD_RF = 4.3 V, VDD_A = 3.4 V, VDD_X = 3.4 V Manual Mode (1) 14 x = don't care Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Table 5-2. Supply Regulator Setting: 3-V System Register Address Option Bits Setting in Regulator Control Register (1) B7 B6 B5 B4 B3 B2 B1 B0 Comments Automatic Mode (default) 0B 1 x x x x x 1 1 Automatic regulator setting 250-mV difference 0B 1 x x x x x 1 0 Automatic regulator setting 350-mV difference 0B 1 x x x x x 0 0 Automatic regulator setting 400-mV difference 0B 0 x x x x 1 1 1 VDD_RF = 3.4 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 x x x x 1 1 0 VDD_RF = 3.3 V, VDD_A = 3.3 V, VDD_X = 3.3 V 0B 0 x x x x 1 0 1 VDD_RF = 3.2 V, VDD_A = 3.2 V, VDD_X = 3.2 V 0B 0 x x x x 1 0 0 VDD_RF = 3.1 V, VDD_A = 3.1 V, VDD_X = 3.1 V 0B 0 x x x x 0 1 1 VDD_RF = 3.0 V, VDD_A = 3.0 V, VDD_X = 3.0 V 0B 0 x x x x 0 1 0 VDD_RF = 2.9 V, VDD_A = 2.9 V, VDD_X = 2.9 V 0B 0 x x x x 0 0 1 VDD_RF = 2.8 V, VDD_A = 2.8 V, VDD_X = 2.8 V 0B 0 x x x x 0 0 0 VDD_RF = 2.7 V, VDD_A = 2.7 V, VDD_X = 2.7 V Manual Mode (1) x = don't care The regulator configuration function adjusts the regulator outputs by default to 250 mV below VIN level, but not higher than 5 V for VDD_RF, 3.4 V for VDD_A and VDD_X. This ensures the highest possible supply voltage for the RF output stage while maintaining an adequate PSRR (power supply rejection ratio). To further improve the PSRR, it is possible to increase the target voltage difference across VDD_X and VDD_A from its default to 350 mV or even 400 mV (for details, see Regulator and I/O Control register 0x0B definition and Table 5-2.) 5.5 Power Modes The chip has several power states, which are controlled by two input pins (EN and EN2) and several bits in the Chip Status Control register (0x00). Table 5-3 is a consolidated table showing the configuration for the different power modes when using a 5V or 3-V system supply. The main reader enable signal is pin EN. When EN is set high, all of the reader regulators are enabled, the 13.56-MHz oscillator is running and the SYS_CLK (output clock for external microcontroller) is also available. The Regulator Control register settings shown are for optimized power out. The automatic setting (normally 0x87) is optimized for best PSRR and noise reduction. Table 5-3. Power Modes (1) Mode EN2 EN Chip Status Control Register (0x00) Mode 4 (Full Power) 5 VDC x 1 21 07 On On On x On 130 23 Mode 4 (Full Power) 3.3 VDC x 1 20 07 On On On x On 67 18 Mode 3 (Half Power) 5 VDC x 1 31 07 On On On x On 70 20 Mode 3 (Half Power) 3.3 VDC x 1 30 07 On On On x On 53 15 (1) Regulator Control Register (0x0B) Transmitter Receiver SYS_CLK (13.56 MHz) SYS_CLK (60 kHz) VDD_X Typical Current (mA) Typical Power Out (dBm) Time (From Previous State) ~20-25 s ~20-25 s x = don't care Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 15 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com Table 5-3. Power Modes(1) (continued) Mode EN2 EN Chip Status Control Register (0x00) Mode 2 5 VDC x 1 03 07 Off On On x On 10.5 -- Mode 2 3.3 VDC x 1 02 00 Off On On x On 9 -- Mode 1 5 VDC x 1 01 07 Off Off On x On 5 -- ~20-25 s Mode 1 3.3 VDC x 1 00 00 Off Off On x On 3 Standby Mode 5 VDC x 1 81 07 Off Off On x On 3 -- 4.8 ms Standby Mode 3.3 VDC x 1 80 00 Off Off On x On 2 -- Sleep Mode 1 0 x x Off Off Off On On 0.120 -- 1.5 ms Power Down 0 0 x x Off Off Off Off Off <0.001 -- Start Regulator Control Register (0x0B) Transmitter Receiver SYS_CLK (13.56 MHz) SYS_CLK (60 kHz) VDD_X Typical Current (mA) Typical Power Out (dBm) Time (From Previous State) ~20-25 s The input pin EN2 has two functions: * A direct connection from EN2 to VIN to ensure the availability of the regulated supply VDD_X and an auxiliary clock signal (60 kHz, SYS_CLK) for an external MCU. This mode (EN = 0, EN2 = 1) is intended for systems in which the MCU is also being supplied by the reader supply regulator (VDD_X) and the MCU clock is supplied by the SYS_CLK output of the reader. This allows the MCU supply and clock to be available during sleep mode. * EN2 enables the start-up of the reader system from complete power down (EN = 0, EN2 = 0). In this case, the EN input is being controlled by the MCU (or other system device) that is without supply voltage during complete power down (thus unable to control the EN input). A rising edge applied to the EN2 input (which has an approximately 1-V threshold level) starts the reader supply system and 13.56MHz oscillator (identical to condition EN = 1). When user MCU is controlling EN and EN2, a delay of 5 ms between EN and EN2 must be used. In cases where MCU is only controlling EN, EN2 is recommended to be connected to either VIN or GND, depending on the application MCU requirements/needs for VDD_X and SYS_CLK. NOTE Using EN=1 and EN2=1 in parallel at start up should not be done as it may cause incorrect operation. This start-up mode lasts until all of the regulators have settled and the 13.56-MHz oscillator has stabilized. If the EN input is set high (EN = 1) by the MCU (or other system device), the reader stays active. If the EN input is not set high (EN = 0) within 100 s after the SYS_CLK output is switched from auxiliary clock (60 kHz) to high-frequency clock (derived from the crystal oscillator), the reader system returns to complete Power-Down Mode 1. This option can be used to wake the reader system from complete Power Down (PD Mode 1) by using a pushbutton switch or by sending a single pulse. After the reader EN line is high, the other power modes are selected by control bits within the Chip Status Control register (0x00). The power mode options and states are listed in Table 5-3. When EN is set high (or on rising edge of EN2 and then confirmed by EN = 1) the supply regulators are activated and the 13.56-MHz oscillator started. When the supplies are settled and the oscillator frequency is stable, the SYS_CLK output is switched from the auxiliary frequency of 60 kHz to the 13.56-MHz frequency derived from the crystal oscillator. At this time, the reader is ready to communicate and perform the required tasks. The MCU can then program the Chip Status Control register 0x00 and select the operation mode by programming the additional registers. 16 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com * * * * 5.6 5.6.1 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Stand-by Mode (bit 7 = 1 of register 0x00), the reader is capable of recovering to full operation in 100 s. Mode 1 (active mode with RF output disabled, bit 5 = 0 and bit 1 = 0 of register 0x00) is a low-power mode that allows the reader to recover to full operation within 25 s. Mode 2 (active mode with only the RF receiver active, bit 1 = 1 of register 0x00) can be used to measure the external RF field (as described in RSSI measurements paragraph) if reader-to-reader anticollision is implemented. Mode 3 and Mode 4 (active modes with the entire RF section active, bit 5 = 1 of register 0x00) are the normal modes used for normal transmit and receive operations. Receiver - Analog Section Main and Auxiliary Receiver The TRF7962A has two receiver inputs: RX_IN1 (pin 8) and RX_IN2 (pin 9). Each of the inputs is connected to an external capacitive voltage divider to ensure that the modulated signal from the tag is available on at least one of the two inputs. This architecture eliminates any possible communication holes that may occur from the tag to the reader. The two RX inputs (RX_IN1 and RX_IN2) are multiplexed into two receivers-the main receiver and the auxiliary receiver. Only the main receiver is used for reception; the auxiliary receiver is used for signal quality monitoring. Receiver input multiplexing is controlled by bit B3 in the Chip Status Control register (address 0x00). After startup, RX_IN1 is multiplexed to the main receiver which is composed of an RF envelope detection, first gain and band-pass filtering stage, second gain and filtering stage with AGC. Only the main receiver is connected to the digitizing stage which output is connected to the digital processing block. The main receiver also has an RSSI measuring stage, which measures the strength of the demodulated signal (subcarrier signal). The primary function of the auxiliary receiver is to monitor the RX signal quality by measuring the RSSI of the demodulated subcarrier signal (internal RSSI). After startup, RX_IN2 is multiplexed to the auxiliary receiver. The auxiliary receiver has an RF envelope detection stage, first gain and filtering with AGC stage and finally the auxiliary RSSI block. The default MUX setting is RX_IN1 connected to the main receiver and RX_IN2 connected to the auxiliary receiver. To determine the signal quality, the response from the tag is detected by the "main" (pin RX_IN1) and "auxiliary" (pin RX_IN2) RSSI. Both values measured and stored in the RSSI level register (address 0x0F). The MCU can read the RSSI values from the TRF7962A RSSI register and decide if swapping the input signals is preferable or not. Setting B3 in the Chip Status Control register (address 0x00) to 1 connects RX_IN1 (pin 8) to the auxiliary receiver and RX_IN2 (pin 9) to the main receiver. This mechanism must be used to avoid reading holes. The main and auxiliary receiver input stages are RF envelope detectors. The RF amplitude at RX_IN1 and RX_IN2 should be approximately 3 VPP for a VIN supply level greater than 3.3 V. If the VIN level is lower, the RF input peak-to-peak voltage level should not exceed the VIN level. 5.6.2 Receiver Gain and Filter Stages The first gain and filtering stage has a nominal gain of 15 dB with an adjustable band-pass filter. The band-pass filter has programmable 3-dB corner frequencies between 110 kHz to 450 kHz for the highpass filter and between 570 kHz to 1500 kHz for the low-pass filter. After the band-pass filter, there is another gain-and-filtering stage with a nominal gain of 8 dB and with frequency characteristics identical to the first band-pass stage. The internal filters are configured automatically depending on the selected ISO communication standard in the ISO Control register (address 0x01). If required, additional fine tuning can be done by writing directly to the RX special setting registers (address 0x0A). Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 17 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com The main receiver also has a second receiver gain and digitizer stage which is included in the AGC loop. The AGC loop is activated by setting the bit B2 = 1 in the Chip Status Control register (address 0x00). When activated, the AGC continuously monitors the input signal level. If the signal level is significantly higher than an internal threshold level, gain reduction is activated. By default, the AGC is frozen after the first four pulses of the subcarrier signal. This prevents the AGC from interfering with the reception of the remaining data packet. In certain situations, this "AGC freeze" is not optimal, so it can be removed by setting B0 = 1 in the RX Special Setting register (address 0x0A). Table 5-4 shows the various settings for the receiver analog section. Table 5-4. RX Special Setting Register (0x0A) Bit Function B7 Bandpass from 110 kHz to 570 kHz B6 Bandpass from 200 kHz to 900 kHz B5 Bandpass from 450 kHz to 1.5 MHz B4 Bandpass from 100 kHz to 1.5 MHz B3 00 01 10 11 B2 = no gain reduction = gain reduction for 5 dB = gain reduction for 10 dB = gain reduction for 15 dB Comments Appropriate for 424-kHz subcarrier systems used in ISO15693 Sets the RX digital gain reduction (changing the window of the digitizing comparator). B1 0 = 5 times minimum digitizing level 1 = 3 times minimum digitizing level AGC activation level change. From five times higher to the minimum RX digitizing level to three times the minimum digitizing level. The minimum RX digitizing level can be adjusted by B2 and B3 (gain reduction). B0 0 = AGC freeze after 16 subcarrier edges 1 = AGC always on during receive AGC action is not limited in time or to the start of receive. AGC action can be done any time during receive process. The AGC can only increase and, hence, clips on the peak RX level during the enable period. AGC level is reset automatically at the beginning of each receive start frame. 5.7 Receiver - Digital Section The output of the TRF7962A analog receiver block is a digitized subcarrier signal and is the input to the digital receiver block. This block includes a Protocol Bit Decoder section and the Framing Logic section. The protocol bit decoders convert the subcarrier coded signal into a serial bit stream and a data clock. The decoder logic is designed for maximum error tolerance. This enables the decoder section to successfully decode even partly corrupted subcarrier signals that otherwise would be lost due to noise or interference. In the framing logic section, the serial bit stream data is formatted in bytes. Special signals such as the start of frame (SOF), end of frame (EOF), start of communication, and end of communication are automatically removed. The parity bits and CRC bytes are also checked and removed. This "clean" data is then sent to the 12-byte FIFO register where it can be read by the external microcontroller system. Providing the data this way, in conjunction with the timing register settings of the TRF7962A, means the firmware developer has to know about much less of the finer details of the ISO protocols to create a very robust application, especially in low-cost platforms where code space is at a premium and high performance is still required. The start of the receive operation (successfully received SOF) sets the IRQ flags in the IRQ and Status register (0x0C). The end of the receive operation is signaled to the external system MCU by setting pin 13 (IRQ) high. If the receive data packet is longer than 8 bytes, an interrupt is sent to the MCU as the received data occupies 75% of the FIFO capacity. The data should be immediately removed from the FIFO. 18 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Any error in the data format, parity, or CRC is detected and notified to the external system by an interrupt request pulse. The source condition of the interrupt request pulse is available in the IRQ Status register (0x0C). The main register controlling the digital part of the receiver is the ISO Control register (0x01). By writing to this register, the user selects the protocol to be used. With each new write in this register, the default presets are reloaded in all related registers, so no further adjustments in other registers are needed for proper operation. NOTE If register setting changes are needed for fine tuning the system, they must be done after setting the ISO Control register (0x01). The receive section also includes two timers. The RX wait time timer is controlled by the value in the RX Wait Time register (0x08). This timer defines the time interval after the end of the transmit operation in which the receive decoders are not active (held in reset state). This prevents false detections resulting from transients following the transmit operation. The value of the RX Wait Time register (0x08) defines the time in increments of 9.44 s. This register is preset at every write to ISO Control register (0x01) according to the minimum tag response time defined by each standard. The RX no response timer is controlled by the RX No Response Wait Time register (0x07). This timer measures the time from the start of slot in the anticollision sequence until the start of tag response. If there is no tag response in the defined time, an interrupt request is sent and a flag is set in the IRQ Status register (0x0C). This enables the external controller to be relieved of the task of detecting empty slots. The wait time is stored in the register in increments of 37.76 s. This register is also automatically preset for every new protocol selection. 5.7.1 Received Signal Strength Indicator (RSSI) The TRF7962A incorporates in total three independent RSSI building blocks: Internal Main RSSI, Internal Auxiliary RSSI, and External RSSI. The internal RSSI blocks are measuring the amplitude of the subcarrier signal, and the external RSSI block measures the amplitude of the RF carrier signal at the receiver input. 5.7.1.1 Internal RSSI - Main and Auxiliary Receivers Each receiver path has its own RSSI block to measure the envelope of the demodulated RF signal (subcarrier). Internal Main RSSI and Internal Auxiliary RSSI are identical except that they are connected to different RF input pins. The Internal RSSI is intended for diagnostic purposes to set the correct RX path conditions. The Internal RSSI values can be used to adjust the RX gain settings and/or decide which RX path (main or auxiliary) provides the greater amplitude and, hence, to decide if the MUX may need to be reprogrammed to swap the RX input signal. The measuring system latches the peak value, so the RSSI level can be read after the end of each receive packet. The RSSI register values are reset with every transmission (TX) by the reader. This guarantees an updated RSSI measurement for each new tag response. The Internal RSSI has 7 steps (3 bit) with a typical increment of about 4 dB. The operating range is between 600 mVp and 4.2 Vpp with a typical step size of about 600 mV. Both RSSI values "Internal Main" and "Internal Aux" RSSI are stored in the RSSI Levels and Oscillator Status register (0x0F). The nominal relationship between the input RF peak level and the RSSI value is shown in Figure 5-2. Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 19 TRF7962A RSSI Levels and Oscillator Status Register Value (0x0F) SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com 7 6 5 4 3 2 1 0 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 Input RF Carrier Level (VPP) 3 3.25 3.5 3.75 4 4.25 Figure 5-2. Digital Internal RSSI (Main and Auxiliary) Value vs RF Input Level This RSSI measurement is done during the communication to the Tag; this means the TX must be on. Bit 1 in the Chip Status Control register (0x00) defines if internal RSSI or the external RSSI value is stored in the RSSI Levels and Oscillator Status register 0x0F. Direct command 0x18 is used to trigger an internal RSSI measurement. 5.7.1.2 External RSSI The external RSSI is mainly used for test and diagnostic in order to sense the amplitude of any 13.56MHz signal at the receivers RX_IN1 input. The external RSSI measurement is typically done in active mode when the receiver is on but transmitter output is off. The level of the RF signal received at the antenna is measured and stored in the RSSI Levels and Oscillator Status Register 0x0F. The relationship between the voltage at the RX_IN1 input and the 3-bit code is shown in Figure 5-3. 20 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 RSSI Levels and Oscillator Status Register Value (0x0F) www.ti.com 7 6 5 4 3 2 1 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 RF Input Voltage Level at Pin RF_IN1 (mVPP) Figure 5-3. Digital External RSSI Value vs RF Input Level The relation between the 3-bit code and the external RF field strength (A/m) sensed by the antenna must be determined by calculation or by experiments for each antenna design. The antenna Q-factor and connection to the RF input influence the result. Direct command 0x19 is used to trigger an internal RSSI measurement. To 1. 2. 3. check the internal or external RSSI value independent of any other operation, the user must: Set transmitter to desired state (on or off) using Bit 5 of Chip Status Control register (0x00) Set the receiver using direct command 0x17. Check internal or external RSSI using direct commands 0x18 or 0x19, respectively. This action latches/places RSSI value in RSSI register 4. Read RSSI register using direct command 0x0F, values range from 0x40 to 0x7F. 5. Repeat steps 1-4 as desired, as register is reset after read. 5.8 Oscillator Section The 13.56-MHz oscillator is controlled via the Chip Status Control register (0x00) and the EN and EN2 signals. The oscillator generates the RF frequency for the RF output stage and the clock source for the digital section. The buffered clock signal is available at pin 27 (SYS_CLK) for external circuits. B4 and B5 inside the Modulation and SYS_CLK register (0x09) can be used to divide the external SYS_CLK signal at pin 27 by 1, 2, or 4. Typical start-up time from complete power down is in the range of 3.5 ms. During Power Down Mode 2 (EN = 0, EN2 = 1) the frequency of SYS_CLK is switched to 60 kHz (typical). The 13.56-MHz crystal must be connected between pin 31 and pin 32. The external shunt capacitors values for C1 and C2 must be calculated based on the specified load capacitance of the crystal being used. The external shunt capacitors are calculated as two identical capacitors in series plus the stray capacitance of the TRF7962A and parasitic PCB capacitance in parallel to the crystal. The parasitic capacitance (CS , stray and parasitic PCB capacitance) can be estimated at 4 to 5 pF (typical). Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 21 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com As an example, using a crystal with a required load capacitance (CL) of 18 pF, the calculation is as follows (see Figure 5-4): C1= C2 = 2 x (CL - CS) = 2 x (18 pF - 4.5 pF) = 27 pF A 27-pF capacitor must be placed on pins 30 and 31 to ensure proper crystal oscillator operation. CS TRF796xA Pin 32 Pin 31 C1 Crystal C2 Figure 5-4. Crystal Block Diagram Table 5-5 shows the minimum characteristics required for any crystal used with TRF7962A. Table 5-5. TRF7962A Minimum Crystal Requirements Parameter Specification Frequency 13.56 MHz Mode of operation Fundamental Type of resonance Parallel Frequency tolerance 20 ppm Aging <5 ppm/year Operation temperature range -40C to 85C Equivalent series resistance 50 As an alternative, an external clock oscillator source can be connected to pin 31 to provide the system clock, and pin 32 can be left open. 5.9 Transmitter - Analog Section The 13.56-MHz oscillator generates the RF signal for the PA stage. The power amplifier consists of a driver with selectable output resistance of 4 or 8 (typical). The transmit power levels are selectable between 100 mW (half power) or 200 mW (full power) when configured for 5-V automatic operation. Selection of the transmit power level is set by bit B4 in the Chip Status Control register (0x00). When configured for 3-V automatic operation, the transmit power level is typically in the range of 33 mW (half power) or 70 mW (full power). The ASK modulation depth is controlled by bits B0, B1, and B2 in the Modulator and SYS_CLK Control register (0x09). The ASK modulation depth range can be adjusted between 7% to 30% or 100% (OOK). External control of the transmit modulation depth is possible by setting the ISO Control register (0x01) to Direct Mode. While operating the TRF7962A in Direct Mode, the transmit modulation is made possible by selecting the modulation type ASK or OOK at pin 12. External control of the modulation type is made possible only if enabled by setting B6 in the Modulator and SYS_CLK Control register (0x09) to 1. In normal operation mode, the length of the modulation pulse is defined by the protocol selected in the ISO Control register (0x01). In case of a high-Q antenna, the modulation pulse is typically prolonged, and the tag detects a longer pulse than intended. For such cases, the modulation pulse length must be corrected by using the TX Pulse Length register (0x06). If the register contains all zeros, then the pulse length is governed by the protocol selection. If the register contains a value other than 0x00, the pulse length is equal to the value of the register multiplied by 73.7 ns. This means the pulse length can be adjusted between 73.7 ns and 18.8 s in 73.7-ns increments. 22 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 5.10 Transmitter - Digital Section The digital part of the transmitter is a mirror of the receiver. The settings controlled the ISO Control register (0x01) are applied to the transmitter just like the receiver. In the TRF7962A default mode (ISO Mode), the TRF7962A automatically adds all the special signals like start of communication, end of communication, SOF, EOF, parity bits and CRC bytes. The data is then coded to modulation pulse levels and sent to the RF output stage modulation control unit. Just like with the receiver, this means that the external system MCU only has to load the FIFO with data and all the micro-coding is done automatically, again saving the firmware developer code space and time. Additionally, all the registers used for transmit parameter control are automatically preset to optimum values when a new selection is entered into the ISO Control register (0x01). NOTE The FIFO must be reset before starting any transmission with Direct Command 0x0F. There are two ways to start the transmit operation: * It can be started by loading the number of bytes to be sent (address 0x1D and 0x1E) and data to be loaded in the FIFO (address 0x1F) followed by a transmit command (described in direct commands section). In this case, the transmission then starts exactly on the transmit command. * It is also possible to send the transmit command and information on the number of bytes to be transmitted first and then start to send the data to FIFO. In this case, the transmission starts when first data byte is written into the FIFO. NOTE If the data length is longer than the FIFO, the external system MCU is warned when the majority of data from the FIFO was already transmitted by sending and interrupt request with flag in IRQ register to indicate a FIFO low/high status. The external system should respond by loading next data packet into the FIFO. At the end of a transmit operation, the external system MCU is notified by interrupt request (IRQ) with a flag in IRQ register (0x0C) indicating TX is complete (example value = 0x80). 5.11 Transmitter - External Power Amplifier / Subcarrier detector The TRF7962A can be used in conjunction with an external TX power amplifier and/or external subcarrier detector for the receiver path. If this is the case, certain registers must be programmed as shown here: * Bit B6 of the Regulator and I/O Control register (0x0B) must be set to 1. This setting has two functions: First, to provide a modulated signal for the transmitter, if needed. Second, to configure the TRF7962A receiver inputs for an external demodulated subcarrier input. * Bit B3 of the Modulation and SYS_CLK Control register (0x09) to 1 (see Section 6.1.2.4). This function configures the ASK/OOK pin for either a digital or analog output (B3 = 0 enables a digital output, and B3 = 1 enables an analog output). The design of an external power amplifier requires detailed RF knowledge. There are also readily designed and certified high-power HF reader modules on the market. 5.12 TRF7962A Communication Interface 5.12.1 General Introduction The communication interface to the reader can be configured in two ways: with a eight line parallel interface (D0:D7) plus DATA_CLK, or with a three or four wire Serial Peripheral Interface (SPI). The SPI interface uses traditional Master Out/Slave In (MOSI), Master In, Slave Out (MISO), IRQ, and DATA_CLK lines. The SPI can be operated with or without using the Slave Select line. Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 23 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com These communication modes are mutually exclusive; meaning, only one mode can be used at a time in the application. When the SPI interface is selected, the unused I/O_2, I/O_1, and I/O_0 pins must be hard-wired according to Table 5-6. At power up, the TRF7962A IC samples the status of these three pins. If they are not the same (all High or all Low) it enters one of the possible SPI modes. The TRF7962A always behaves as the slave, while the microcontroller (MCU) behaves as the master device. The MCU initiates all communications with the TRF7962A. The TRF7962A makes use of the Interrupt Request (IRQ) pin in both parallel and SPI modes to prompt the MCU for servicing attention. Table 5-6. Pin Assignment in Parallel and Serial Interface Connection or Direct Mode Pin Parallel DATA_ CLK DATA_CLK I/O_7 A/D[7] I/O_6 (4) SPI With SS SPI Without SS DATA_CLK from master Direct mode, data out (subcarrier or bit stream) Direct mode, strobe (bit clock out) DATA_CLK from master MOSI (1) = data in (reader in) MOSI (1) = data in (reader in) MISO (2) = data out (MCU out) MISO (2) = data out (MCU out) See (3) A/D[5] I/O_4 A/D[4] I/O_3 A/D[3] - - - I/O_2 A/D[2] - At VDD At VDD I/O_1 A/D[1] - At VDD At VSS I/O_0 A/D[0] - At VSS At VSS IRQ interrupt IRQ interrupt SS (slave select) IRQ interrupt IRQ interrupt See (3) I/O_5 (3) IRQ (1) (2) (3) A/D[6] Parallel Direct DATA_CLK (4) - MOSI = Master Out, Slave In MISO = Master In, Slave Out The I/O_5 pin is used only for information when data is put out of the chip (for example, reading 1 byte from the chip). It is necessary first to write in the address of the register (8 clocks) and then to generate another 8 clocks for reading out the data. The I/O_5 pin goes high during the second 8 clocks. But for normal SPI operations I/O_5 pin is not used. The slave select pin is active low. Communication is initialized by a start condition, which is expected to be followed by an Address/Command word (Adr/Cmd). The Adr/Cmd word is 8 bits long, and its format is shown in Table 57. Table 5-7. Address/Command Word Bit Distribution Bit 24 Description Bit Function Address Command B7 Command control bit 0 = address 1 = command 0 1 B6 Read/Write 1 = read 0 = write R/W 0 B5 Continuous address mode 1 = continuous mode R/W 0 B4 Address/command bit 4 Adr 4 Cmd 4 B3 Address/command bit 3 Adr 3 Cmd 3 B2 Address/command bit 2 Adr 2 Cmd 2 B1 Address/command bit 1 Adr 1 Cmd 1 B0 Address/command bit 0 Adr 0 Cmd 0 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 The MSB (bit 7) determines if the word is to be used as a command or as an address. The last two columns of Table 5-7 show the function of the separate bits if either address or command is written. Data is expected once the address word is sent. In continuous address mode (continuous mode = 1), the first data that follows the address is written (or read) to (from) the given address. For each additional data, the address is incremented by one. Continuous mode can be used to write to a block of control registers in a single stream without changing the address; for example, setup of the predefined standard control registers from the MCU non-volatile memory to the reader. In non-continuous address mode (simple addressed mode), only one data word is expected after the address. Address Mode is used to write or read the configuration registers or the FIFO. When writing more than 12 bytes to the FIFO, the Continuous Address Mode should be set to 1. The Command Mode is used to enter a command resulting in reader action (for example, initialize transmission, enable reader, and turn reader on/off). Examples of expected communications between an MCU and the TRF7962A are shown. Table 5-8. Continuous Address Mode Start Adr x Data(x) Data(x+1) Data(x+2) Data(x+3) Data(x+4) ... Data(x+n) StopCont Figure 5-5. Continuous Address Register Write Example Starting With Register 0x00 (Using SPI With SS Mode) Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 25 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com Figure 5-6. Continuous Address Register Read Example Starting With Register 0x00 (Using SPI With SS Mode) Table 5-9. Non-Continuous Address Mode (Single Address Mode) Start Adr x Data(x) Adr y Data(y) ... Adr z Data(z) StopSgl Figure 5-7. Single Address Register Write Example of Register 0x00 (Using SPI With SS Mode) 26 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Figure 5-8. Single Address Register Read Example of Register 0x00 (Using SPI With SS Mode) Table 5-10. Direct Command Mode Start Cmd x (Optional data or command) Stop Figure 5-9. Direct Command Example of Sending 0x0F (Reset) (Using SPI With SS Mode) The other Direct Command Codes from MCU to TRF7962A are described in Section 5.13. 5.12.2 FIFO Operation The FIFO is a 12-byte register at address 0x1F with byte storage locations 0 to 11. FIFO data is loaded in a cyclical manner and can be cleared by a reset command (0x0F, see graphic above showing this Direct Command). Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 27 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com Associated with the FIFO are two counters and three FIFO status flags. The first counter is a 4-bit FIFO byte counter (bits B0 to B3 in register 0x1C) that keeps track of the number of bytes loaded into the FIFO. If the number of bytes in the FIFO is n, the register value is n - 1 (number of bytes in FIFO register). If 8 bytes are in the FIFO, the FIFO counter (bits B0 to B3 in register 0x1C) has the value 7. A second counter (12 bits wide) indicates the number of bytes being transmitted (registers 0x1D and 0x1E) in a data frame. An extension to the transmission-byte counter is a 4-bit broken-byte counter also provided in register 0x1E (bits B0 to B3). Together these counters make up the TX length value that determines when the reader generates the EOF byte. FIFO status flags are as follows: 1. FIFO overflow (bit B4 of register 0x1C): Indicates that the FIFO was loaded too soon 2. FIFO level too low (bit B5 of register 0x1C): Indicates that only three bytes are left to be transmitted (Can be used during transmission.) 3. FIFO level high (bit B6 of register 0x1C): Indicates that nine bytes are already loaded into the FIFO (Can be used during reception to generate a FIFO reception IRQ. This is to notify the MCU to service the reader in time to ensure a continuous data stream.) During transmission, the FIFO is checked for an almost-empty condition, and during reception for an almost-full condition. The maximum number of bytes that can be loaded into the FIFO in a single sequence is 12 bytes. NOTE The number of bytes in a frame, transmitted or received, can be greater than 12 bytes. During transmission, the MCU loads the TRF7962A FIFO (or, during reception, the MCU removes data from the FIFO), and the FIFO counter counts the number of bytes being loaded into the FIFO. Meanwhile, the byte counter keeps track of the number of bytes being transmitted. An interrupt request is generated if the number of bytes in the FIFO is less than 3 or greater than 9, so that MCU can send new data or remove the data as necessary. The MCU also checks the number of data bytes to be sent, so as to not surpass the value defined in TX length bytes. The MCU also signals the transmit logic when the last byte of data is sent or was removed from the FIFO during reception. Transmission starts automatically after the first byte is written into FIFO. Figure 5-10. Checking the FIFO Status Register (Using SPI With SS Mode) 28 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 5.12.3 Parallel Interface Mode In parallel mode, the start condition is generated on the rising edge of the I/O_7 pin while the CLK is high. This is used to reset the interface logic. Figure 5-11 shows the sequence of the data, with an 8-bit address word first, followed by data. Communication is ended by: * The StopSmpl condition, where a falling edge on the I/O_7 pin is expected while CLK is high * The StopCont condition, where the I/O_7 pin must have a successive rising and falling edge while CLK is low in order to reset the parallel interface and be ready for the new communication sequence * The StopSmpl condition is also used to terminate the Direct Mode. Figure 5-11. Parallel Interface Communication With Simple Stop Condition (StopSmpl) Figure 5-12. Parallel Interface Communication With Continuous Stop Condition (StopCont) Figure 5-13. Parallel Interface Communication With Continuous Stop Condition Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 29 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com 5.12.3.1 Reception of Air Interface Data At the start of a receive operation (when SOF is successfully detected), B6 is set in the IRQ Status register. An interrupt request is sent to the MCU at the end of the receive operation if the receive data string was shorter than or equal to 8 bytes. The MCU receives the interrupt request, then checks to determine the reason for the interrupt by reading the IRQ Status register (address 0x0C), after which the MCU reads the data from the FIFO. If the received packet is longer than 8 bytes, the interrupt is sent before the end of the receive operation when the ninth byte is loaded into the FIFO (75% full). The MCU should again read the content of the IRQ Status register to determine the cause of the interrupt request. If the FIFO is 75% full (as marked with flag B5 in IRQ Status register and by reading the FIFO Status register), the MCU should respond by reading the data from FIFO to make room for new incoming receive data. When the receive operation is finished, the interrupt is sent and the MCU must check how many words are still present in the FIFO before it finishes reading. If the reader detects a receive error, the corresponding error flag is set (framing error, CRC error) in the IRQ Status register, indicating to the MCU that reception was not completed correctly. 5.12.3.2 Data Transmission to MCU Before beginning data transmission, the FIFO should always be cleared with a reset command (0x0F). Data transmission is initiated with a selected command (see Section 5.13). The MCU then commands the reader to do a continuous write command (0x3D) (see Table 5-7) starting from register 0x1D. Data written into register 0x1D is the TX length byte 1 (upper and middle nibbles), while the following byte in register 0x1E is the TX length byte 2 (lower nibble and broken byte length). Note that the TX byte length determines when the reader sends the EOF byte. After the TX length bytes are written, FIFO data is loaded in register 0x1F with byte storage locations 0 to 11. Data transmission begins automatically after the first byte is written into the FIFO. The loading of TX length bytes and the FIFO can be done with a continuous write command, as the addresses are sequential. At the start of transmission, the flag B7 (IRQ_TX) is set in the IRQ Status register. If the transmit data is shorter than or equal to 4 bytes, the interrupt is sent only at the end of the transmit operation. If the number of bytes to be transmitted is higher or equal to 5, then the interrupt is generated. This occurs also when the number of bytes in the FIFO reaches 3. The MCU should check the IRQ Status register and FIFO Status register and then load additional data to the FIFO, if needed. At the end of the transmit operation, an interrupt is sent to inform the MCU that the task is complete. 5.12.4 Serial Interface Communication (SPI) When an SPI interface is utilized, I/O pins, I/O_2, I/O_1, and I/O_0, must be hard wired according to Table 5-7. On power up, the TRF7962A looks for the status of these pins; if they are not the same (not all high, or not all low), the reader enters into one of two possible SPI modes: * SPI with slave select or * SPI without slave select The choice of one of these modes over the other should be made based on the available GPIOs and the desired control of the system. The serial communications work in the same manner as the parallel communications with respect to the FIFO, except for the following condition. On receiving an IRQ from the reader, the MCU reads the TRF7962A IRQ Status register to determine how to service the reader. After this, the MCU must to do a dummy read to clear the reader's IRQ Status register. The dummy read is required in SPI mode, because the reader's IRQ Status register needs an additional clock cycle to clear the register. This is not required in parallel mode, because the additional clock cycle is included in the Stop condition. 30 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 A procedure for a dummy read is as follows: 1. Starting the dummy read (a) When using slave select (SS): set SS bit low (b) When not using SS: start condition is when SCLK is high 2. Send address word to IRQ Status register (0x0C) with read and continuous address mode bits set to 1 3. Read 1 byte (8 bits) from IRQ Status register (0x0C) 4. Dummy-read 1 byte from register 0Dh (collision position and interrupt mask) 5. Stopping the dummy read (a) When using slave select (SS): set SS bit high (b) When not using SS: stop condition when SCLK is high Write Address Byte (0x6C) Read Data in IRQ Status Register Dummy Read DATA_CLK MOSI MISO 0 1 1 0 1 1 Don't Care 0 0 No Data Transitions (All High/Low) B7 B6 B5 B4 B3 B2 B1 B0 No Data Transitions (All High/Low) Ignore SLAVE SELECT Figure 5-14. Procedure for Dummy Read Figure 5-15. Dummy Read Using SPI With SS 5.12.4.1 Serial Interface Mode Without Slave Select (SS) The serial interface without the slave select pin must use delimiters for the start and stop conditions. Between these delimiters, the address, data, and command words can be transferred. All words must be 8 bits long with MSB transmitted first (see Figure 5-16). Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 31 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com Start Condition Stop Condition Data Clock 50 ns Data In b7 b6 b5 b4 b3 b2 b1 b0 Data Out Figure 5-16. SPI Without Slave Select Timing In this mode, a rising edge on data in (I/O_7, pin 24) while SCLK is high resets the serial interface and prepares it to receive data. Data in can change only when SCLK is low, and it is read by the reader on the SCLK rising edge. Communication is terminated by the stop condition when the data in falling edge occurs during a high SCLK period. 5.12.4.2 Serial Interface Mode With Slave Select (SS) The serial interface is in reset while the Slave Select signal is high. Serial data in (MOSI) changes on the falling edge, and is validated in the reader on the rising edge, as shown in Figure 5-17. Communication is terminated when the Slave Select signal goes high. All words must be 8 bits long with the MSB transmitted first. tSTE,LEAD Slave Select Write Mode CKPH = 1, CKPL = 0 Data Transition is on tSTE,LAG Data Clock Falling Edge MOSI Valid on Data Clock Rising Edge Read Mode CKPH = 0, CKPL = 0 Data Transition is on tSTE,LAG Data Clock Rising Edge MOSI Valid on Data Clock Falling Edge Switch DATA_CLK Polarity 1/fUCxCLK Data Clock tLO/HI tLO/HI tSU,SO tHD,SI tSU,SI MOSI b7 b6 to b1 No Data Transitions (All High/Low) b0 tHD,SO tVALID,SO MISO Don't Care b7 b6... ...b1 tSTE,DIS b0 Figure 5-17. SPI With Slave Select Timing The read command is sent out on the MOSI pin, MSB first, in the first eight clock cycles. MOSI data changes on the falling edge, and is validated in the reader on the rising edge, as shown in Figure 5-17. During the write cycle, the serial data out (MISO) is not valid. After the last read command bit (B0) is validated at the eighth rising edge of SCLK, after half a clock cycle, valid data can be read on the MISO pin at the falling edge of SCLK. It takes eight clock edges to read out the full byte (MSB first). When using the hardware SPI (for example, an MSP430 hardware SPI) to implement this feature, care must be taken to switch the SCLK polarity after write phase for proper read operation. The example clock polarity for the MSP430-specific environment is shown in the write-mode and read-mode boxes of Figure 5-17. See the USART-SPI chapter for any specific microcontroller family for further information on the setting the appropriate clock polarity. This clock polarity switch must be done for all read (single, continuous) operations. The MOSI (serial data out) should not have any transitions (all high or all low) during the read cycle. The Slave Select should be low during the whole write and read operation. See Section 3.5, Switching Characteristics, for the timing values shown in Figure 5-17. The continuous read operation is shown in Figure 5-18. 32 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Write Address Byte Read Data Byte 1 B7 B6 B5 B4 B3 B2 B1 B0 No Data Transitions (All High/Low) Read Data Byte n DATA_CLK MOSI MISO Don't Care B7 B6 B5 B4 B3 B2 B1 B0 No Data Transitions (All High/Low) B7 B6 B5 B4 B3 B2 B1 B0 SLAVE SELECT Figure 5-18. Continuous Read Operation Using SPI With Slave Select Figure 5-19. Continuous Read of Registers 0x00 Through 0x05 Using SPI With SS Performing a Single Slot Inventory Command as an example is shown in Figure 5-20. Reader registers (in this example) are configured for 5-VDC input and default operation. Full sequences for other settings and protocols can be downloaded here: http://www.ti.com/lit/zip/sloc240. Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 33 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com Figure 5-20. Inventory Command Sent From MCU to TRF7962A The TRF7962A reads these bytes from the MCU and then sends out Request Flags, Inventory Command, and Mask over the air to the ISO15693 transponder. After these three bytes have been transmitted, an interrupt occurs from the reader to indicate back to the MCU that the transmission has been completed. In the example shown in Figure 5-21, this IRQ occurs approximately 1.6 ms after the SS line goes high after the Inventory command is sent out. Figure 5-21. IRQ After Inventory Command The IRQ Status register read (0x6C) yields 0x80, which indicates that TX is complete. This is followed by dummy clock and reset of FIFO with dummy clock. Then, if a tag is in the field and no error is detected by the reader, a second interrupt is expected and occurs (in this example) approximately 4 ms after first IRQ is read and cleared. 34 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 In the continuation of the example (see Figure 5-22), the IRQ Status register is read using method previously recommended, followed by a single read of the FIFO Status register, which indicates that there are at least 9 bytes to be read out. Figure 5-22. IRQ Status Register Read Followed by FIFO Status Register Read This is followed by a continuous read of the FIFO (see Figure 5-23). The first byte is 0x00 for no error. The next byte is the DSFID (usually shipped by manufacturer as 0x00), then the UID, shown here up to the next most significant byte, the MFG code (0x07 to indicate TI silicon). Figure 5-23. Continuous Read of FIFO Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 35 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com This is followed by another IRQ approximately 160 s later, as there is still one byte in FIFO, the MSB of the UID, which must be retrieved (see Figure 5-24). IRQ register read shows RX is complete and FIFO register status shows one byte available, as expected and it is the E0, indicating ISO15693 transponder. Figure 5-24. IRQ With One Byte in FIFO At this time, the application should reset the FIFO and read out the RSSI value of the tag (see Figure 525). In this case, the transponder is very close to the antenna, so value of 0x7E is recovered. Figure 5-25. Reset FIFO and Read RSSI 36 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 5.12.5 Direct Mode Direct mode allows the reader to be configured in one of two ways. Direct Mode 0 (bit 6 = 0, as defined in ISO Control register) allows the application to use only the frontend functions of the reader, bypassing the protocol implementation in the reader. For transmit functions, the application has direct access to the transmit modulator through the MOD pin (pin 14). On the receive side, the application has direct access to the subcarrier signal (digitized RF envelope signal) on I/O_6 (pin 23). Direct Mode 1 (bit 6 = 1, as defined in ISO Control register) uses the subcarrier signal decoder of the selected protocol (as defined in ISO Control register). This means that the receive output is not the subcarrier signal but the decoded serial bit stream and bit clock signals. The serial data is available on I/O_6 (pin 23), and the bit clock is available on I/O_5 (pin 22). The transmit side is identical; the application has direct control over the RF modulation through the MOD input. This mode is provided so that the application can implement a protocol that has the same bit coding as one of the protocols implemented in the reader, but needs a different framing format. To select Direct Mode, first choose which Direct Mode to enter by writing B6 in the ISO Control register. This bit determines if the receive output is the direct subcarrier signal (B6 = 0) or the serial data of the selected decoder. If B6 = 1, then the application must also define which protocol should be used for bit decoding by writing the appropriate setting in the ISO Control register. The reader actually enters the Direct Mode when B6 (direct) is set to 1 in the Chip Status Control register. Direct mode starts immediately. The write command should not be terminated with a stop condition (see communication protocol), because the stop condition terminates the Direct Mode and clears B6. This is necessary as the Direct Mode uses one or two I/O pins (I/O_6 and I/O_5). Normal parallel communication is not possible in Direct Mode. Sending a stop condition terminates Direct Mode. Figure 5-26 shows the different configurations available in Direct Mode. * In mode 0, the reader is used as an AFE only, and protocol handling is bypassed. * In mode 1, framing is not done, but SOF and EOF are present. This allows for a user-selectable framing level based on an existing ISO standard. * In mode 2, data is ISO standard formatted. SOF, EOF, and error checking are removed, so the microprocessor receives only bytes of raw data via a 12-byte FIFO. Analog Front End (AFE) Direct Mode 0: Raw RF Sub-Carrier Data Stream ISO15693 Encoders/Decoders Direct Mode 1: Raw Digital ISO Coded Data Without Protocol Frame Packetization/Framing Microcontroller ISO Mode: Full ISO Framing and Error Checking (Typical Mode) Figure 5-26. User-Configurable Modes Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 37 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com The steps to enter Direct Mode are listed below, using SPI with SS communication method only as one example, as Direct Mode(s) are also possible with parallel and SPI without SS. The application must enter Direct Mode 0 to accommodate non-ISO standard compliant card type communications. Direct Mode can be entered at any time, so that if a card type started with ISO standard communications, then deviated from the standard after being identified and selected, the ability to go into Direct Mode 0 becomes very useful. Step 1: Configure pins I/O_0 to I/O_2 for SPI with SS Step 2: Set pin 12 of the TRF7962A (ASK/OOK pin) to 0 for ASK or 1 for OOK Step 3: Program the TRF7962A registers The following registers need to be explicitly set before going into Direct Mode. 1. ISO Control register (0x01) to the appropriate standard: - 0x02 for ISO 15693 high data rate (26.48 kbps) 2. Modulator and SYS_CLK Register (0x09) to the appropriate clock speed and modulation: - 0x21 for 6.78-MHz clock and OOK (100%) modulation - 0x20 for 6.78-MHz clock and ASK 10% modulation - 0x24 for 6.78-MHz clock and ASK 13% modulation - 0x25 for 6.78-MHz clock and ASK 16% modulation See register 0x09 definition for all other possible values. Step 4: Enter Direct Mode The following registers must be reprogrammed to enter Direct Mode: a. Set bit B6 of the Modulator and SYS_CLK Control register (0x09) to 1. b. Set bit B6 of the ISO Control register (0x01) to 0 for Direct Mode 0 (default its 0) c. Set bit B6 of the Chip Status Control register (0x00) to 1 to enter Direct Mode (do not send a Stop condition after this command) NOTE - - It is important that the last write be NOT terminated with Stop condition. For SPI, this means that Slave Select (I/O_4) continues to stay low. Sending a Stop condition terminates the Direct Mode and clears bit B6 in the Chip Status Control register (0x00). NOTE Access to registers, FIFO, and IRQ is not available during Direct Mode 0. Remember that the reader enters Direct Mode 0 when bit 6 of the Chip Status Control register (0x00) is set to a 1, and it stays in Direct Mode 0 until a Stop condition is sent from the microcontroller. NOTE The write command should not be terminated with a Stop condition (for example, in SPI mode this is done by bringing the SS line high after the register write), because the Stop condition terminates the Direct Mode and clears bit 6 of the Chip Status Control register (0x00), making it a 0. 38 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Figure 5-27. Entering Direct Mode 0 Step 5: Transmit data using Direct Mode The user now has direct control over the RF modulation through the MOD input. TRF796xA Microcontroller MOD (Pin 14) Drive the MOD pin according to the data-coding specified by the standard IO6 (Pin 23) Decode the subcarrier information according to the standard Figure 5-28. Control of RF Modulation Using MOD The microcontroller is responsible for generating data according to the coding specified by the particular standard. The microcontroller must generate SOF, EOF, data, and CRC. In Direct Mode, the FIFO is not used and no IRQs are generated. See the applicable ISO standard to understand bit and frame definitions. Step 6: Receive data using Direct Mode After the TX operation is complete, the tag responds to the request and the subcarrier data is available on pin I/O_6. The microcontroller must decode the subcarrier signal according to the standard. This includes decoding the SOF, data bits, CRC, and EOF. The CRC then must be checked to verify data integrity. The receive data bytes must be buffered locally. Step 7: Exit Direct Mode 0 When an EOF is received, data transmission is over, and Direct Mode 0 can be terminated by sending a Stop condition (the SS signal goes high). The TRF7962A returns to ISO Mode (normal mode). Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 39 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com 5.13 Direct Commands from MCU to Reader 5.13.1 Command Codes Table 5-11 lists the valid commands that the MCU can send to the reader. Table 5-11. Command Codes Command Code Command Comments 0x00 Idle 0x03 Software Initialization 0x0F Reset 0x10 Transmission without CRC 0x11 Transmission with CRC 0x14 End of Frame/Transmit Next Time Slot 0x16 Block Receiver 0x17 Enable Receiver 0x18 Test external RF (RSSI at RX input with TX on) 0x19 Test internal RF (RSSI at RX input with TX off) 0x1A Receiver Gain Adjust Same as power on reset ISO15693 The command code values from Table 5-11 are substituted in Table 5-12, Bits 0 through 4. Also, the most-significant bit (MSB) in Table 5-12 must be set to 1. Table 5-12. Address/Command Word Bit Distribution Bit Description Bit Function Address Command B7 Command control bit 0 = address 1 = command 0 1 B6 Read/Write 0 = write 1 = read R/W 0 B5 Continuous address mode Continuous mode Not used B4 Address/Command bit 4 Adr 4 Cmd 4 B3 Address/Command bit 3 Adr 3 Cmd 3 B2 Address/Command bit 2 Adr 2 Cmd 2 B1 Address/Command bit 1 Adr 1 Cmd 1 B0 Address/Command bit 0 Adr 0 Cmd 0 The MSB determines if the word is to be used as a command or address. The last two columns of Table 5-12 show the function of separate bits depending on whether address or command is written. Command mode is used to enter a command resulting in reader action (for example, initialize transmission, enable reader, or turn the reader on or off). 5.13.2 Reset (0x0F) The reset command clears the FIFO contents and FIFO Status register (0x1C). It also clears the register storing the collision error location (0x0E). 5.13.3 Transmission With CRC (0x11) The transmission command must be sent first, followed by transmission length bytes, and FIFO data. The reader starts transmitting after the first byte is loaded into the FIFO. The CRC byte is included in the transmitted sequence. 40 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 5.13.4 Transmission Without CRC (0x10) The transmission command must be sent first, followed by transmission length bytes, and FIFO data. The reader starts transmitting after the first byte is loaded into the FIFO. This is the same as the previous section ( Section 5.13.3), except that the CRC is not included. 5.13.5 Transmit Next Time Slot (0x14) When this command is received, the reader transmits the next slot command. The next slot sign is defined by the protocol selection. 5.13.6 Block Receiver (0x16) The block receiver command puts the digital part of receiver (bit decoder and framer) in reset mode. This is useful in an extremely noisy environment, where the noise level could otherwise cause a constant switching of the subcarrier input of the digital part of the receiver. The receiver (if not in reset) would try to catch a SOF signal, and if the noise pattern matched the SOF pattern, an interrupt would be generated, falsely signaling the start of an receive operation. A constant flow of interrupt requests can be a problem for the external system (MCU), so the external system can stop this by putting the receive decoders in reset mode. The reset mode can be terminated in two ways: The external system can send the enable receiver command (see Section 5.13.7). The reset mode is automatically terminated at the end of a transmit operation. The receiver can stay in reset after end of transmit if the RX Wait Time register (0x08) is set. In this case, the receiver is enabled at the end of the wait time following the transmit operation. 5.13.7 Enable Receiver (0x17) This command clears the reset mode in the digital part of the receiver if the reset mode was entered by the block receiver command. 5.13.8 Test Internal RF (RSSI at RX Input With TX On) (0x18) The level of the RF carrier at RF_IN1 and RF_IN2 inputs is measured. Operating range between 300 mVP and 2.1 VP (step size is 300 mV). The two values are reported in the RSSI Levels register (0x0F). The command is intended for diagnostic purposes to set correct RF_IN levels. Optimum RFIN input level is approximately 1.6 VP or code 5 to 6. The nominal relationship between the RF peak level and RSSI code is described in Table 5-13 and in Section 5.7.1.1. NOTE If the command is executed immediately after power-up and before any communication with tag was performed, the command must be preceded by the Enable RX command. The Check RF commands require full operation, so the receiver must be activated by enable receive or by a normal tag communication for the Check RF command to work properly. Table 5-13. Test Internal RF RF_IN1 (mVP): Decimal Code: Binary Code: 300 600 900 1200 1500 1800 2100 1 2 3 4 5 6 7 001 010 011 001 101 011 111 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 41 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com 5.13.9 Test External RF (RSSI at RX Input With TX Off) (0x19) This command can be used in active mode when the RF receiver is on but RF output is off. This means bit B1 = 1 in the Chip Status Control register. The level of RF signal received on the antenna is measured and reported in the RSSI Levels register (0x0F). The relation between the 3-bit code and the external RF field strength [A/m] must be determinate by calculation or by experiments for each antenna type, because the antenna Q and connection to the RF input influence the result. The nominal relation between the RF peak to peak voltage in the RF_IN1 input and RSSI code is shown in Table 5-14 and in Section 5.7.1.2. NOTE If the command is executed immediately after power-up and before any communication with tag was performed, the command must be preceded by the Enable RX command. The Check RF commands require full operation, so the receiver must be activated by enable RX or by a normal tag communication for the Check RF command to work properly. Table 5-14. Test External RF RF_IN1 (mVP): 40 60 80 100 140 180 300 Decimal Code: 1 2 3 4 5 6 7 001 010 011 001 101 011 111 Binary Code: 5.13.10 Receiver Gain Adjust (0x1A) This command should be executed when the MCU determines that no tag response is detected and when the RF and receivers are on. When this command is received, the reader observes the digitized receiver output. If more than two edges are observed in 100 ms, the window comparator voltage is increased. The procedure is repeated until the number of edges (changes of logical state) of the digitized reception signal is less than 2 (in 100 ms). The command can reduce the input sensitivity in 5-dB increments up to 15 dB. This command ensures better operation in a noisy environment. The gain setting is reset to maximum gain at EN = 0, POR = 1. 5.13.11 Register Preset After power-up and the EN pin low-to-high transition, the reader is in the default mode. The default configuration is ISO15693, single subcarrier, high data rate, 1-out-of-4 operation. The low-level option registers (0x02 to 0x0B) are automatically set to adapt the circuitry optimally to the appropriate protocol parameters. When entering another protocol (by writing to the ISO Control register), the low-level option registers are automatically configured to the new protocol parameters. After selecting the protocol, it is possible to change some low-level register contents if needed. However, changing to another protocol and then back reloads the default settings; therefore, the custom settings must be reloaded. The Clo0 and Clo1 bits in the Modulator and SYS_CLK Control register (0x09), which define the microcontroller frequency available on the SYS_CLK pin, are the only two bits in the configuration registers that are not cleared during protocol selection. 42 Detailed System Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6 Register Description 6.1 Register Overview Table 6-1 lists the registers available in the TRF7962A. These registers are described in the following sections. Table 6-1. Register Overview Address (hex) Register Read/Write Section Main Control Registers 0x00 Chip Status Control R/W Section 6.1.1.1 0x01 ISO Control R/W Section 6.1.1.2 Protocol Sub-Setting Registers 0x06 TX Pulse-Length Control R/W Section 6.1.2.1 0x07 RX No Response Wait R/W Section 6.1.2.2 0x08 RX Wait Time R/W Section 6.1.2.3 0x09 Modulator and SYS_CLK Control R/W Section 6.1.2.4 0x0A RX Special Setting R/W Section 6.1.2.5 0x0B Regulator and I/O Control R/W Section 6.1.2.6 R Section 6.1.3.1 R/W Section 6.1.3.2 Status Registers 0x0C IRQ Status 0x0D Collision Position and Interrupt Mask Register 0x0E Collision Position R Section 6.1.3.2 0x0F RSSI Levels and Oscillator Status R Section 6.1.3.3 FIFO Registers 0x1A Test R/W Section 6.1.4.1 0x1B Test R/W Section 6.1.4.2 0x1C FIFO Status R Section 6.1.5.1 0x1D TX Length Byte1 R/W Section 6.1.5.2 0x1E TX Length Byte2 R/W Section 6.1.5.2 0x1F FIFO I/O Register R/W Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 43 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6.1.1 www.ti.com Main Configuration Registers 6.1.1.1 Chip Status Control Register (0x00) Table 6-2. Chip Status Control Register (0x00) Function: Control of power mode, RF on/off, AGC, AM/PM, Direct Mode Default Settings: Register default is 0x01. It is preset at EN = L or POR = H Bit No. Bit Name B7 stby B6 B5 Function 1 = Standby Mode Standby mode keeps all supply regulators and the 13.56-MHz SYS_CLK oscillator running (typical start-up time to full operation is 100 s). 0 = Active Mode Active Mode (default) 1 = Direct Mode 0/1 Provides user direct access to AFE (Direct Mode 0) or allows user to add their own framing (Direct Mode 1). Bit 6 of ISO Control register must be set by user before entering Direct Mode 0 or 1. 0 = ISO Mode (default) Uses SPI or parallel communication with automatic framing and ISO decoders 1 = RF output active Transmitter on, receivers on 0 = RF output not active Transmitter off direct rf_on 1 = Half output power B4 Description TX_OUT (pin 5) = 8- output impedance P = 100 mW (+20 dBm) at 5 V, P = 33 mW (+15 dBm) at 3.3 V rf_pwr 0 = Full output power TX_OUT (pin 5) = 4- output impedance P = 200 mW (+23 dBm) at 5 V, P = 70 mW (+18 dBm) at 3.3 V B3 B2 B1 B0 44 pm_on agc_on rec_on vrs5_3 1 = Selects Main RX input RX_IN1 input is used 0 = Selects Aux RX input RX_IN2 input is used 1 = AGC on Enables AGC (AGC gain can be set in register 0x0A) 0 = AGC off AGC block is disabled 1 = Receiver activated for external field measurement Forces enabling of receiver and TX oscillator. Used for external field measurement. 0 = Automatic enable Allows enable of the receiver via bit 5 of this register 1 = 5-V operation 0 = 3-V operation Selects the VIN voltage range Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com 6.1.1.2 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 ISO Control Register (0x01) Table 6-3. ISO Control Register (0x01) Function: Controls the selection of ISO standard protocol, Direct Mode, and receive CRC Default Settings: Register default is 0x02 (ISO15693 high bit rate, one subcarrier, 1 out of 4). It is reset at EN = L or POR = H. Bit No. Bit Name B7 rx_crc_n Function CRC receive selection Description 1 = no RX CRC (CRC not present in the response) 0 = RX CRC (CRC is present in the response) B6 Direct mode type selection dir_mode B5 rfid RFID / Reserved 0 = Direct Mode 0 1 = Direct Mode 1 0 = RFID mode 1 = Reserved (should be set to 0) B4 iso_4 RFID B3 iso_3 RFID B2 iso_2 RFID B1 iso_1 RFID B0 iso_0 RFID See Table 6-4 for B0:B4 settings based on the ISO protocol that the application requires Table 6-4. ISO Control Register: ISO_4 to ISO_0 ISO_4 ISO_3 ISO_2 ISO_1 ISO_0 0 0 0 0 0 ISO15693 low bit rate, 6.62 kbps, one subcarrier, 1 out of 4 Protocol Remarks 0 0 0 0 1 ISO15693 low bit rate, 6.62 kbps, one subcarrier, 1 out of 256 0 0 0 1 0 ISO15693 high bit rate, 26.48 kbps, one subcarrier, 1 out of 4 0 0 0 1 1 ISO15693 high bit rate, 26.48 kbps, one subcarrier, 1 out of 256 0 0 1 0 0 ISO15693 low bit rate, 6.67 kbps, double subcarrier, 1 out of 4 0 0 1 0 1 ISO15693 low bit rate, 6.67 kbps, double subcarrier, 1 out of 256 0 0 1 1 0 ISO15693 high bit rate, 26.69 kbps, double subcarrier, 1 out of 4 0 0 1 1 1 ISO15693 high bit rate, 26.69 kbps, double subcarrier, 1 out of 256 Default for reader Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 45 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6.1.2 www.ti.com Protocol Sub-Setting Registers 6.1.2.1 TX Pulse Length Control Register (0x06) The length of the modulation pulse is defined by the protocol selected in the ISO Control register (0x01). With a high-Q antenna, the modulation pulse is typically prolonged, and the tag detects a longer pulse than intended. For such cases, the modulation pulse length can be corrected by using the TX pulse length register 0x06. If the register contains all zeros, then the pulse length is governed by the protocol selection. If the register contains a value other than 0x00, the pulse length is equal to the value of the register in 73.7-ns increments. This means the range of adjustment can be 73.7 ns to 18.8 s. Table 6-5. TX Pulse Length Control Register (0x06) Function: Controls the length of TX pulse Default Settings: Default is set to 0x00 at POR = H or EN = L and at each write to ISO Control register. Bit No. Bit Name B7 Pul_p2 B6 Pul_p1 B5 Pul_p0 B4 Pul_c4 B3 Pul_c3 B2 Pul_c2 B1 Pul_c1 B0 Pul_c0 6.1.2.2 Function Description Pulse length MSB The pulse range is 73.7 ns to 18.8 s (1 to 255), step size 73.7 ns All bits low (00): pulse length control is disabled The following default timings are preset by the ISO Control register (0x01): 9.44 s ISO15693 (TI Tag-It HF-I) Pulse length LSB RX No Response Wait Time Register (0x07) The RX no response timer is controlled by the RX No Response Wait Time register. This timer measures the time from the start of slot in the anticollision sequence until the start of tag response. If there is no tag response in the defined time, an interrupt request is sent and a flag is set in IRQ Status Control register (0x0C). This enables the external controller to be relieved of the task of detecting empty slots. The wait time is stored in the register in increments of 37.76 s. This register is also preset, automatically, for every new protocol selection. Table 6-6. RX No Response Wait Time Register (0x07) Function: Defines the time when "no response" interrupt is sent Default Settings: Default is set to 0x0E at POR = H or EN = L and at each write to ISO Control register. 46 Bit No. Bit Name B7 NoResp7 B6 NoResp6 B5 NoResp5 B4 NoResp4 B3 NoResp3 B2 NoResp2 B1 NoResp1 B0 NoResp0 Function Description No response MSB Defines the time when no response interrupt is sent. It starts from the end of TX EOF. RX no response wait range is 37.76 s to 9628 s (1 to 255). Step size is 37.76 s. The following default timings are preset by the ISO Control register (0x01): 755 s ISO15693 high data rate (TI Tag-It HF-I) 1812 s ISO15693 low data rate (TI Tag-It HF-I) No response LSB Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com 6.1.2.3 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 RX Wait Time Register (0x08) The RX wait time timer is controlled by the value in the RX Wait Time register. This timer defines the time after the end of the transmit operation in which the receive decoders are not active (held in reset state). This prevents incorrect detections resulting from transients following the transmit operation. The value of the RX wait time register defines this time in increments of 9.44 s. This register is preset at every write to ISO Control register according to the minimum tag response time defined by each standard. Table 6-7. RX Wait Time Register (0x08) Function: Defines the time after TX EOF when the RX input is disregarded; for example, to block out electromagnetic disturbance generated by the responding card. Default Settings: Default is set to 0x1F at POR = H or EN = L and at each write to the ISO control register. Bit No. Bit Name B7 Rxw7 B6 Rxw6 B5 Rxw5 B4 Rxw4 B3 Rxw3 B2 Rxw2 B1 Rxw1 B1 Rxw0 Function Description Defines the time after the TX EOF during which the RX input is ignored. Time starts from the end of TX EOF. RX wait time RX wait range is 9.44 s to 2407 s (1 to 255). Step size is: 9.44 s. The following default timings are preset by the ISO Control register (0x01): 293 s ISO15693 (TI Tag-It HF-I) Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 47 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6.1.2.4 www.ti.com Modulator and SYS_CLK Control Register (0x09) The frequency of SYS_CLK (pin 27) is programmable by the bits B4 and B5 of this register. The frequency of the TRF7962A system clock oscillator is divided by 1, 2 or 4 resulting in available SYS_CLK frequencies of 13.56 MHz or 6.78 MHz or 3.39 MHz. The ASK modulation depth is controlled by bits B0, B1 and B2. The range of ASK modulation is 7% to 30% or 100% (OOK). The selection between ASK and OOK (100%) modulation can also be done using direct input OOK (pin 12). The direct control of OOK/ASK using OOK pin is only possible if the function is enabled by setting B6 = 1 (en_ook_p) in this register (0x09) and the ISO Control register (0x01, B6 = 1). When configured this way, the MOD (pin 14) is used as input for the modulation signal. Table 6-8. Modulator and SYS_CLK Control Register (0x09) Function: Controls the modulation input and depth, ASK / OOK control and clock output to an external system (an MCU) Default Settings: Default is set to 0x11 at POR = H or EN = L, and at each write to the ISO Control register, except Clo1 and Clo0. Bit No. Bit Name B7 Unused B6 en_ook_p Function Description Enable ASK/OOK pin (pin 12) for "on the fly change" between any 1 = enables external selection of pre-selected ASK modulation as defined by B0 to B2 and OOK ASK or OOK modulation modulation. 0 = default operation as defined If B6 is set to 1, pin 12 is configured as follows: in bits B0 to B2 of this register 1 = OOK modulation 0 = Modulation as defined in B0 to B2 (0x09) B5 B4 Clo0 B3 en_ana B2 Pm2 B1 B0 48 Clo1 Pm1 Pm0 SYS_CLK output frequency MSB SYS_CLK output frequency LSB Clo1 Clo0 0 0 SYS_CLK Output Disabled 0 1 3.39 MHz 1 0 6.78 MHz 1 1 13.56 MHz 1 = sets pin 12 (ASK/OOK) as an For test and measurement purpose. ASK/OOK pin 12 can be used analog output to monitor the analog subcarrier signal before the digitizing with DC level equal to AGND. 0 = default Modulation depth MSB Modulation depth Modulation depth LSB Pm2 Pm1 Pm0 0 0 0 ASK 10% 0 0 1 OOK (100%) 0 1 0 ASK 7% 0 1 1 ASK 8.5% 1 0 0 ASK 13% 1 0 1 ASK 16% 1 1 0 ASK 22% 1 1 1 ASK 30% Register Description Modulation Type and Percentage Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com 6.1.2.5 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 RX Special Setting Register (0x0A) Table 6-9. RX Special Setting Register (0x0A) Function: Sets the gains and filters directly Default Settings: Default is set to 0x40 at POR = H or EN = L, and at each write to the ISO Control register (0x01). Bit No. Bit Name B7 C212 Bandpass 110 kHz to 570 kHz B6 C424 Bandpass 200 kHz to 900 kHz B5 M848 Bandpass 450 kHz to 1.5 MHz B4 hbt Bandpass 100 kHz to 1.5 MHz Gain reduced for 18 dB B3 gd1 B2 gd2 B1 B0 agcr no-lim Function 00 01 10 11 = gain reduction 0 dB = gain reduction for 5 dB = gain reduction for 10 dB = gain reduction for 15 dB Description Appropriate for 424-kHz subcarrier used in ISO15693 Sets the RX gain reduction and reduces sensitivity AGC activation level change AGC activation level changed from five times the digitizing level to three times the digitizing level. 1 = 3x 0 = 5x AGC action is not limited in time AGC action can be done any time during receive process. It is not limited to the start of receive ("max hold"). 1 = continuously, no time limit 0 = 8 subcarrier pulses The first four steps of the AGC control are comparator adjustment. The second three steps are gain reduction done automatically by AGC control. The AGC is turned on after TX. The first gain and filtering stage following the RF envelope detector has a nominal gain of 15, and the 3dB band-pass frequencies are adjustable in the range from 100 kHz to 400 kHz for high pass and 600 kHz to 1.5 MHz for low pass. The next gain and filtering stage has a nominal gain of 8, and the frequency characteristic identical to first stage. The filter setting is done automatically with internal preset for each new selection of communication standard in the ISO Control register. Additional corrections can be done by directly writing into the RX Special Setting register. The second receiver gain stage and digitizer stage are included in the AGC loop. The AGC loop can be activated by setting the bit B2 = 1 (agc-on) in the Chip Status Control register. If activated the AGC monitors the signal level at the input of digitizing stage. If the signal level is significantly higher than the digitizing threshold level, the gain reduction is activated. The signal level, at which the action is started, is by default five times the digitizing threshold level. It can be reduced to three times the digitizing level by setting bit B1 = 1 (agcr) in the RX Special Setting register. The AGC action typically finishes after four subcarrier pulses. By default, the AGC action is blocked after first few pulses of subcarrier signal so AGC cannot interfere with signal reception during rest of data packet. In certain cases, this is not optimal, so this blocking can be removed by setting B0 = 1 (no_lim) in the RX Special Setting register. NOTE The setting of bits b4, b5, b6, and b7 to zero selects bandpass characteristic of 240 kHz to 1.4 MHz. Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 49 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6.1.2.6 www.ti.com Regulator and I/O Control Register (0x0B) Table 6-10. Regulator and I/O Control Register (0x0B) Function: Control the three voltage regulators Default Settings: Default is set to 0x87 at POR = H or EN = L Bit No. Bit Name B7 auto_reg Function Description Automatic system settings: VDD_RF = VIN - 250 mV VDD_A = VIN - 250 mV VDD_X = VIN - 250 mV, but not higher than 3.4 V 0 = Manual system 1 = Automatic system Manual system settings: See B2 to B0 B6 en_ext_pa Support for external power amplifier Internal peak detectors are disabled, receiver inputs (RX_IN1 and RX_IN2) accept externally demodulated subcarrier. At the same time, the ASK/OOK pin becomes modulation output for external TX amplifier. B5 io_low 1 = Enable low peripheral communication voltage When B5 = 1, maintains the output driving capabilities of the I/O pins connected to the level shifter under low-voltage operation. Should be set 1 when VDD_I/O voltage is between 1.8 V and 2.7 V. B4 Unused No function Default is 0. B3 Unused No function Default is 0. B2 vrs2 B1 vrs1 B0 vrs0 Voltage set MSB vrs3_5 = L: VDD_RF, VDD_A, VDD_X range 2.7 V to 3.4 V. See Table 6-11 through Table 6-14. Voltage set LSB Table 6-11. Supply Regulator Setting, Manual 5-V System Register Option Bits Setting in Control Register B7 B6 B5 B4 B3 B2 B1 00 50 Action B0 1 5-V system 0B 0 Manual regulator setting 0B 0 1 1 1 VDD_RF = 5 V, VDD_A = 3.5 V, VDD_X = 3.4 V 0B 0 1 1 0 VDD_RF = 4.9 V, VDD_A = 3.5 V, VDD_X = 3.4 V 0B 0 1 0 1 VDD_RF = 4.8 V, VDD_A = 3.5 V, VDD_X = 3.4 V 0B 0 1 0 0 VDD_RF = 4.7 V, VDD_A = 3.5 V, VDD_X = 3.4 V 0B 0 0 1 1 VDD_RF = 4.6 V, VDD_A = 3.5 V, VDD_X = 3.4 V 0B 0 0 1 0 VDD_RF = 4.5 V, VDD_A = 3.5 V, VDD_X = 3.4 V 0B 0 0 0 1 VDD_RF = 4.4 V, VDD_A = 3.5 V, VDD_X = 3.4 V 0B 0 0 0 0 VDD_RF = 4.3 V, VDD_A = 3.5 V, VDD_X = 3.4 V Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Table 6-12. Supply Regulator Setting, Manual 3-V System Register Option Bits Setting in Control Register B7 B6 B5 B4 B3 B2 B1 00 Action B0 0 3-V system 0B 0 Manual regulator setting 0B 0 1 1 1 VDD_RF = 3.4 V, VDD_A = 3.4 V, VDD_X = 3.4 V 0B 0 1 1 0 VDD_RF = 3.3 V, VDD_A = 3.3 V, VDD_X = 3.3 V 0B 0 1 0 1 VDD_RF = 3.2 V, VDD_A = 3.2 V, VDD_X = 3.2 V 0B 0 1 0 0 VDD_RF = 3.1 V, VDD_A = 3.1 V, VDD_X = 3.1 V 0B 0 0 1 1 VDD_RF = 3.0 V, VDD_A = 3.0 V, VDD_X = 3.0 V 0B 0 0 1 0 VDD_RF = 2.9 V, VDD_A = 2.9 V, VDD_X = 2.9 V 0B 0 0 0 1 VDD_RF = 2.8 V, VDD_A = 2.8 V, VDD_X = 2.8 V 0B 0 0 0 0 VDD_RF = 2.7 V, VDD_A = 2.7 V, VDD_X = 2.7 V Table 6-13. Supply Regulator Setting, Automatic 5-V System Register Option Bits Setting in Control Register B7 B6 B5 B4 B3 B2 (1) B1 00 (1) Action B0 1 5-V system 0B 1 x 1 1 Automatic regulator setting 250-mV difference 0B 1 x 1 0 Automatic regulator setting 350-mV difference 0B 1 x 0 0 Automatic regulator setting 400-mV difference x = don't care Table 6-14. Supply Regulator Setting, Automatic 3-V System Register Option Bits Setting in Control Register B7 B6 B5 B4 B3 B2 (1) B1 00 (1) Action B0 0 3-V system 0B 1 x 1 1 Automatic regulator setting 250-mV difference 0B 1 x 1 0 Automatic regulator setting 350-mV difference 0B 1 x 0 0 Automatic regulator setting 400-mV difference x = don't care Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 51 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6.1.3 www.ti.com Status Registers 6.1.3.1 IRQ Status Register (0x0C) Table 6-15. IRQ Status Register (0x0C) Function: Information available about TRF7962A IRQ and TX/RX status Default Settings: Default is set to 0x00 at POR = H or EN = L, and at each write to the ISO Control Register 0x01. It is also automatically reset at the end of a read phase. The reset also removes the IRQ flag. Bit No. Bit Name Function Description B7 Irq_tx IRQ set due to end of TX Signals that TX is in progress. The flag is set at the start of TX but the interrupt request (IRQ = 1) is sent when TX is finished. B6 Irg_srx IRQ set due to RX start Signals that RX SOF was received and RX is in progress. The flag is set at the start of RX but the interrupt request (IRQ = 1) is sent when RX is finished. B5 Irq_fifo FIFO is high or low Signals when the FIFO is high or low (more than 8 bits during RX or less than 4 bits during TX). See Section 5.12.2 for details. B4 Irq_err1 CRC error Indicates receive CRC error only if B7 (no RX CRC) of ISO Control register is set to 0. B3 Irq_err2 Parity error Indicates parity error B2 Irq_err3 Byte framing or EOF error Indicates framing error B1 Irq_col Collision error Collision error for ISO15693 single subcarrier. Collision error bit can also be triggered by external noise. B0 Irq_noresp No-response time interrupt No response within the "No-response time" defined in RX Noresponse Wait Time register (0x07). Signals the MCU that next slot command can be sent. To reset (clear) the register 0x0C and the IRQ line, the register must be read. During transmit, the decoder is disabled, and only bits B5 and B7 can be changed. During receive, only bit B6 can be changed, but does not trigger the IRQ line immediately. The IRQ signal is set at the end of the transmit or receive phase. 52 Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com 6.1.3.2 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Collision Position and Interrupt Mask Registers (0x0D and 0x0E) Table 6-16. Collision Position and Interrupt Mask Register (0x0D) Default Settings: Default is set to 0x3E at POR = H and EN = L. Collision bits reset automatically after read operation. Bit No. Bit Name B7 Col9 Bit position of collision MSB B6 Col8 Bit position of collision B5 En_irq_fifo Interrupt enable for FIFO Default = 1 B4 En_irq_err1 Interrupt enable for CRC Default = 1 B3 En_irq_err2 Interrupt enable for Parity Default = 1 En_irq_err3 Interrupt enable for Framing error or EOF Default = 1 B1 En_irq_col Interrupt enable for collision error Default = 1 B0 En_irq_noresp B2 Function Enables no-response interrupt Description Default = 0 Table 6-17. Collision Position Register (0x0E) Function: Displays the bit position of collision or error Default Settings: Default is set to 0x00 at POR = H and EN = L. Automatically reset after read operation. Bit No. Bit Name B7 Col7 B6 Col6 B5 Col5 B4 Col4 B3 Col3 B2 Col2 B1 Col1 B0 Col0 Function Description Bit position of collision MSB This register shows the bit position of error. Either frame, SOF/EOF, parity, or CRC error. Bit position of collision LSB Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 53 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6.1.3.3 www.ti.com RSSI Levels and Oscillator Status Register (0x0F) Table 6-18. RSSI Levels and Oscillator Status Register (0x0F) Function: Displays the signal strength on both reception channels and RF amplitude during RF-off state. The RSSI values are valid from reception start until the start of the next transmission. Bit No. Bit Name B7 Unused Function B6 osc_ok Crystal oscillator stable indicator B5 rssi_x2 MSB RSSI value of auxiliary RX (RX_IN2) B4 rssi_x1 Auxiliary channel RSSI B3 rssi_x0 MSB RSSI value of auxiliary RX (RX_IN2) B2 rssi_2 MSB RSSI value of Main RX (RX_IN1) B1 rssi_1 Main channel RSSI B0 rssi_0 LSB RSSI value of Main RX (RX_IN1) Description 13.56-MHz frequency stable (approximately 200 s) Auxiliary channel is by default RX_IN2. The input can be swapped by B3 = 1 (Chip State Control register). If "swapped", the auxiliary channel is connected to RX_IN1 and the auxiliary RSSI represents the signal level at RX_IN1. Active channel is the default and can be set with option bit B3 = 0 of the Chip Status Control register (0x00). RSSI measurement block is measuring the demodulated envelope signal (except in case of direct command for RF amplitude measurement described later in direct commands section). The measuring system is latching the peak value, so the RSSI level can be read after the end of receive packet. The RSSI value is reset during next transmit action of the reader, so the new tag response level can be measured. The RSSI levels calculated to the RF_IN1 and RF_IN2 are shown in Section 5.7.1.1 and Section 5.7.1.2. The RSSI has 7 steps (3 bits) with 4-dB increment. The input level is the peak to peak modulation level of RF signal measured on one side envelope (positive or negative). 54 Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com 6.1.4 SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Test Registers 6.1.4.1 Test Register (0x1A) Table 6-19. Test Register (0x1A) (for Test or Direct Use) Default Settings: Default is set to 0x00 at POR = H and EN = L. Bit No. Bit Name B7 OOK_Subc_In Function Subcarrier input MOD_Subc_Ou Subcarrier output t B6 B5 MOD_Direct B4 o_sel Description OOK Pin becomes decoder digital input MOD Pin becomes receiver subcarrier output Direct TX modulation and RX reset First stage output selection MOD Pin becomes receiver subcarrier output 0 = First stage output used for analog out and digitizing 1 = Second stage output used for analog out and digitizing B3 low2 Second stage gain -6 dB, HP corner frequency/2 B2 low1 First stage gain -6 dB, HP corner frequency/2 B1 zun Input followers test B0 Test_AGC 6.1.4.2 AGC test, AGC level is seen on rssi_210 bits Test Register (0x1B) Table 6-20. Test Register (0x1B) (for Test or Direct Use) Default Settings: Default is set to 0x00 at POR = H and EN = L. When a test_dec or test_io is set, IC is switched to test mode. Test Mode persists until a stop condition arrives. At stop condition the test_dec and test_io bits are cleared. Bit No. Bit Name B7 test_rf_level Function Description RF level test B6 B5 B4 B3 test_io1 B2 test_io0 I/O test Not implemented B1 test_dec Decoder test mode B0 clock_su Coder clock 13.56 MHz For faster test of coders Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 55 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 6.1.5 www.ti.com FIFO Control Registers 6.1.5.1 FIFO Status Register (0x1C) Table 6-21. FIFO Status Register (0x1C) Function: Low nibbles of complete bytes to be transferred through FIFO. Information about a broken byte and number of bits to be transferred from it Bit No. Bit Name B7 RFU B7 = 0 Reserved for future use (RFU) B6 Fhil FIFO level high Indicates that 9 bytes are already in the FIFO (for RX) (also see register 0x0C bit 5) B5 Flol FIFO level low Indicates that only 3 bytes are in the FIFO (for TX) (also see register 0x0C bit 5) B4 Fove FIFO overflow error Too many bytes were written to the FIFO B3 Fb3 FIFO bytes fb[3] B2 Fb2 FIFO bytes fb[2] B1 Fb1 FIFO bytes fb[1] B0 Fb0 FIFO bytes fb[0] 6.1.5.2 Function Description Bits B0:B3 indicate how many bytes that are loaded in FIFO were not read out yet (displays N - 1 number of bytes). If 8 bytes are in the FIFO, this number is 7 (also see register 0x0C bit 6). TX Length Byte1 Register (0x1D) and TX Length Byte2 Register (0x1E) Table 6-22. TX Length Byte1 Register (0x1D) Function: High two nibbles of complete intended bytes to be transferred through FIFO Default Settings: Default is set to 0x00 at POR and EN = 0. It is also automatically reset at TX EOF. Bit No. Bit Name Function B7 Txl11 Number of complete byte bn[11] B6 Txl10 Number of complete byte bn[10] B5 Txl9 Number of complete byte bn[9] B4 Txl8 Number of complete byte bn[8] B3 Txl7 Number of complete byte bn[7] B2 Txl6 Number of complete byte bn[6] B1 Txl5 Number of complete byte bn[5] B0 Txl4 Number of complete byte bn[4] Description High nibble of complete intended bytes to be transmitted High nibble of complete intended bytes to be transmitted Table 6-23. TX Length Byte2 Register (0x1E) Function: Low nibbles of complete bytes to be transferred through FIFO. Information about a broken byte and number of bits to be transferred from it. Default Settings: Default is set to 0x00 at POR and EN = 0. It is also automatically reset at TX EOF. 56 Bit No. Bit Name Function Description B7 Txl3 Number of complete byte bn[3] B6 Txl2 Number of complete byte bn[2] B5 Txl1 Number of complete byte bn[1] B4 Txl0 Number of complete byte bn[0] B3 Bb2 Broken byte number of bits bb[2] B2 Bb1 Broken byte number of bits bb[1] B1 Bb0 Broken byte number of bits bb[0] It is taken into account only when broken byte flag is set. B0 Bbf Broken byte flag B0 = 1 indicates that last byte is not complete 8 bits wide. High nibble of complete intended bytes to be transmitted Number of bits in the last broken byte to be transmitted. Register Description Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 7 System Design 7.1 Layout Considerations Keep all decoupling capacitors as close to the IC as possible, with the high-frequency decoupling capacitors (10 nF) closer than the low-frequency decoupling capacitors (2.2 F). Place ground vias as close as possible to the ground side of the capacitors and reader IC pins to minimize any possible ground loops. It is not recommend using any inductor sizes below 0603 as the output power can be compromised. If smaller sized inductors are absolutely necessary, the designer must confirm output performance. Pay close attention to the required load capacitance of the used crystal and adjust the two external shunt capacitors accordingly. Follow the recommendations of the crystal manufacturer for those values. There should be a common ground plane for the digital and analog sections. The multiple ground sections or "islands" should have vias that tie the different sections of the planes together. Ensure that the exposed thermal pad at the center of the IC is properly laid out. It should be tied to ground to help dissipate heat from the package. Trace line lengths should be minimized whenever possible, particularly the RF output path, crystal connections, and control lines from the reader to the microprocessor. Proper placement of the TRF7962A, microprocessor, crystal, and RF connection/connector help facilitate this. Avoid crossing of digital lines under RF signal lines. Also, avoid crossing of digital lines with other digital lines whenever possible. If the crossings are unavoidable, 90 crossings should be used to minimize coupling of the lines. Depending on the production test plan, the designer should consider possible implementations of test pads and/or test vias for use during testing. The necessary pads/vias should be placed in accordance with the proposed test plan to help enable easy access to those test points. If the system implementation is complex (for example, if the RFID reader module is a subsystem of a larger system with other modules such as Bluetooth, WiFi, microprocessors, and clocks), special considerations should be taken to ensure that there is no noise coupling into the supply lines. If needed, special filtering or regulator considerations should be used to minimize or eliminate noise in these systems. For more information/details on layout considerations, see the TRF796x HF-RFID Reader Layout Design Guide (SLOA139). 7.2 Impedance Matching TX_Out (Pin 5) to 50 The output impedance of the TRF7962A when operated at full power out setting is nominally 4 + j0 (4 real). This impedance must be matched to a resonant circuit and TI recommends matching circuit from 4 to 50 , as commercially available test equipment (for example, spectrum analyzers, power meters, and network analyzers) are 50- systems. See Figure 7-1 and Figure 7-2 for an impedance match reference circuit. This section explains how the values were calculated. Starting with the 4- source, Figure 7-1 and Figure 7-2 shows the process of going from 4 to 50 by showing it represented on a Smith Chart simulator (available from http://www.fritz.dellsperger.net/). The elements are grouped together where appropriate. System Design Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 57 TRF7962A SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 www.ti.com Figure 7-1. Impedance Matching Circuit This yields the following Smith Chart Simulation: Figure 7-2. Impedance Matching Smith Chart Resulting power out can be measured with power meter/spectrum analyzer with power meter function or other equipment capable of making a "hot" measurement. Take care to observe maximum power input levels on test equipment and use attenuators whenever available to avoid any possibility of damage to expensive equipment. Expected output power levels under various operating conditions are shown in Table 5-3. 7.3 Reader Antenna Design Guidelines For HF antenna design considerations using the TRF7962A, see the following documentation: Antenna Matching for the TRF7960 RFID Reader (SLOA135) TRF7960TB HF RFID Reader Module User's Guide, with antenna details at end of manual (SLOU297) 58 System Design Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A TRF7962A www.ti.com SLOS757A - DECEMBER 2011 - REVISED JUNE 2012 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Revision SLOS757 SLOS757A Description Production Data release Section 3.2, Corrected Power Rating for TA 25C. System Design Copyright (c) 2011-2012, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TRF7962A 59 PACKAGE OPTION ADDENDUM www.ti.com 12-Jun-2012 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) TRF7962ARHBR ACTIVE QFN RHB 32 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TRF7962ARHBT ACTIVE QFN RHB 32 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Samples (Requires Login) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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