PmodACLTM Reference Manual Revision: August 30, 2011 Note: This document applies to REV E of the board. 1300 NE Henley Court, Suite 3 Pullman, WA 99163 (509) 334 6306 Voice | (509) 334 6300 Fax Overview The PmodACL is a 3-axis digital accelerometer module powered by the Analog Devices ADXL345. Features include: * * * * * user-selectable resolution single-tap/double-tap detection activity/inactivity monitoring free fall detection SPI and I2C interfaces Functional Description Interface Connector Signal Description The PmodACL uses a standard 12-pin connector and can communicate via SPI or I2C. A pull-up resistor on the ~SS line keeps the ADXL345 in I2C mode unless the host drives the line low, in which case the device will communicate via SPI. Interface All communications with the device must specify a register address and a flag indicating whether the communication is a read or a write. This is followed by the actual data transfer. Device configuration is performed by writing to control registers within the device. Accelerometer data is accessed by reading device registers. A full list of registers and their functionality, as well as communication specifications, is found in the ADXL345 datasheet available on the Analog Devices website. Doc: 502-097 Connector J1 - SPI Communications Pin Signal Description 1 ~SS Slave Select 2 MOSI / SDA SPI Master out Slave in Data / I2C Data 3 MISO SPI Master in/Slave out Data 4 SCLK Serial Clock 5 GND Power Supply Ground 6 VCC Power Supply (3.3V) 7 INT2 Interrupt 2 8 INT1 Interrupt 1 9 NC Not Connected 10 NC Not Connected 11 GND Power Supply Ground 12 VCC Power Supply (3.3V) The SPI interface standard uses four signal lines. These are slave select (~SS), master out slave in (MOSI), master in slave out (MISO), and serial clock (SCLK). These signals map to the following signals on the ADXL345: ~SS corresponds to the Chip Select signal (~CS), MOSI corresponds to Serial Data Input (SDI), MISO corresponds to Serial Data Output (SDO), and SCK corresponds to the Serial Clock signal (SCLK). page 1 of 2 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners. PmodACL Reference Manual Connector J2 - I2C Communications Pin Signal Description 1, 2 SCLK Serial Clock 3, 4 5, 6 7, 8 SDA / SDI / SDIO GND VCC I2C Data / SPI Master out Slave in Data Power Supply Ground Power Supply (3.3V) The I2C interface standard uses two signal lines. These are I2C data (SDA) and serial clock (SCLK). These signals map to the serial data (SDA) and serial clock (SCLK) respectively on the ADXL345. www.digilentinc.com page 2 of 2 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.