Features
High-performance, Low-power Atmel®AVR® 8-bit Microcontroller
Advanced RISC Architecture
130 Powerful Instructions – Most Single-clock Cycle Execution
32 × 8 General Purpose Working Registers
Fully Static Operation
Up to 16 MIPS Throughput at 16MHz
On-chip 2-cycle Multiplier
High Endurance Non-volatile Memory segments
8Kbytes of In-System Self-programmable Flash program memory
512Bytes EEPROM
1Kbyte Internal SRAM
Write/Erase Cycles: 10,000 Flash/100,000 EEPROM
Data retention: 20 years at 85°C/100 years at 25°C(1)
Optional Boot Code Section with Independent Lock Bits
In-System Programming by On-chip Boot Program
True Read-While-Write Operation
Programming Lock for Software Security
Peripheral Features
Two 8-bit Timer/Counters with Separate Prescaler, one Compare Mode
One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture
Mode
Real Time Counter with Separate Oscillator
Three PWM Channels
8-channel ADC in TQFP and QFN/MLF package
Eight Channels 10-bit Accuracy
6-channel ADC in PDIP package
Six Channels 10-bit Accuracy
Byte-oriented Two-wire Serial Interface
Programmable Serial USART
Master/Slave SPI Serial Interface
Programmable Watchdog Timer with Separate On-chip Oscillator
On-chip Analog Comparator
Special Microcontroller Features
Power-on Reset and Programmable Brown-out Detection
Internal Calibrated RC Oscillator
External and Internal Interrupt Sources
Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, and
Standby
I/O and Packages
23 Programmable I/O Lines
28-lead PDIP, 32-lead TQFP, and 32-pad QFN/MLF
Operating Voltages
2.7V - 5.5V (ATmega8L)
4.5V - 5.5V (ATmega8)
Speed Grades
0 - 8MHz (ATmega8L)
0 - 16MHz (ATmega8)
Power Consumption at 4Mhz, 3V, 25°C
Active: 3.6mA
Idle Mode: 1.0mA
Power-down Mode: 0.5µA
8-bit
with 8KBytes In-
System
Programmable
Flash
ATmega8
ATmega8L
Summary
Rev. 2486ZS–AVR–02/11
2
2486ZS–AVR–02/11
ATmega8(L)
Pin
Configurations
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
(INT1) PD3
(XCK/T0) PD4
GND
VCC
GND
VCC
(XTAL1/TOSC1) PB6
(XTAL2/TOSC2) PB7
PC1 (ADC1)
PC0 (ADC0)
ADC7
GND
AREF
ADC6
AVCC
PB5 (SCK)
32
31
30
29
28
27
26
25
9
10
11
12
13
14
15
16
(T1) PD5
(AIN0) PD6
(AIN1) PD7
(ICP1) PB0
(OC1A) PB1
(SS/OC1B) PB2
(MOSI/OC2) PB3
(MISO) PB4
PD2 (INT0)
PD1 (TXD)
PD0 (RXD)
PC6 (RESET)
PC5 (ADC5/SCL)
PC4 (ADC4/SDA)
PC3 (ADC3)
PC2 (ADC2)
TQFP Top View
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
(RESET) PC6
(RXD) PD0
(TXD) PD1
(INT0) PD2
(INT1) PD3
(XCK/T0) PD4
VCC
GND
(XTAL1/TOSC1) PB6
(XTAL2/TOSC2) PB7
(T1) PD5
(AIN0) PD6
(AIN1) PD7
(ICP1) PB0
PC5 (ADC5/SCL)
PC4 (ADC4/SDA)
PC3 (ADC3)
PC2 (ADC2)
PC1 (ADC1)
PC0 (ADC0)
GND
AREF
AVCC
PB5 (SCK)
PB4 (MISO)
PB3 (MOSI/OC2)
PB2 (SS/OC1B)
PB1 (OC1A)
PDIP
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
32
31
30
29
28
27
26
25
9
10
11
12
13
14
15
16
MLF Top View
(INT1) PD3
(XCK/T0) PD4
GND
VCC
GND
VCC
(XTAL1/TOSC1) PB6
(XTAL2/TOSC2) PB7
PC1 (ADC1)
PC0 (ADC0)
ADC7
GND
AREF
ADC6
AVCC
PB5 (SCK)
(T1) PD5
(AIN0) PD6
(AIN1) PD7
(ICP1) PB0
(OC1A) PB1
(SS/OC1B) PB2
(MOSI/OC2) PB3
(MISO) PB4
PD2 (INT0)
PD1 (TXD)
PD0 (RXD)
PC6 (RESET)
PC5 (ADC5/SCL)
PC4 (ADC4/SDA)
PC3 (ADC3)
PC2 (ADC2)
NOTE:
The large center pad underneath the MLF
packages is made of metal and internally
connected to GND. It should be soldered
or glued to the PCB to ensure good
mechanical stability. If the center pad is
left unconneted, the package might
loosen from the PCB.
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2486ZS–AVR–02/11
ATmega8(L)
Overview The ATmega8 is a low-power CMOS 8-bit microcontroller based on the AVR RISC architecture.
By executing powerful instructions in a single clock cycle, the ATmega8 achieves throughputs
approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption ver-
sus processing speed.
Block Diagram Figure 1. Block Diagram
INTERNAL
OSCILLATOR
OSCILLATOR
WATCHDOG
TIMER
MCU CTRL.
& TIMING
OSCILLATOR
TIMERS/
COUNTERS
INTERRUPT
UNIT
STACK
POINTER
EEPROM
SRAM
STATUS
REGISTER
USART
PROGRAM
COUNTER
PROGRAM
FLASH
INSTRUCTION
REGISTER
INSTRUCTION
DECODER
PROGRAMMING
LOGIC SPI
ADC
INTERFACE
COMP.
INTERFACE
PORTC DRIVERS/BUFFERS
PORTC DIGITAL INTERFACE
GENERAL
PURPOSE
REGISTERS
X
Y
Z
ALU
+
-
PORTB DRIVERS/BUFFERS
PORTB DIGITAL INTERFACE
PORTD DIGITAL INTERFACE
PORTD DRIVERS/BUFFERS
XTAL1
XTAL2
CONTROL
LINES
VCC
GND
MUX &
ADC
AGND
AREF
PC0 - PC6 PB0 - PB7
PD0 - PD7
AVR CPU
TWI
RESET
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2486ZS–AVR–02/11
ATmega8(L)
The AVR core combines a rich instruction set with 32 general purpose working registers. All the
32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent
registers to be accessed in one single instruction executed in one clock cycle. The resulting
architecture is more code efficient while achieving throughputs up to ten times faster than con-
ventional CISC microcontrollers.
The ATmega8 provides the following features: 8 Kbytes of In-System Programmable Flash with
Read-While-Write capabilities, 512 bytes of EEPROM, 1 Kbyte of SRAM, 23 general purpose
I/O lines, 32 general purpose working registers, three flexible Timer/Counters with compare
modes, internal and external interrupts, a serial programmable USART, a byte oriented Two-
wire Serial Interface, a 6-channel ADC (eight channels in TQFP and QFN/MLF packages) with
10-bit accuracy, a programmable Watchdog Timer with Internal Oscillator, an SPI serial port,
and five software selectable power saving modes. The Idle mode stops the CPU while allowing
the SRAM, Timer/Counters, SPI port, and interrupt system to continue functioning. The Power-
down mode saves the register contents but freezes the Oscillator, disabling all other chip func-
tions until the next Interrupt or Hardware Reset. In Power-save mode, the asynchronous timer
continues to run, allowing the user to maintain a timer base while the rest of the device is sleep-
ing. The ADC Noise Reduction mode stops the CPU and all I/O modules except asynchronous
timer and ADC, to minimize switching noise during ADC conversions. In Standby mode, the
crystal/resonator Oscillator is running while the rest of the device is sleeping. This allows very
fast start-up combined with low-power consumption.
The device is manufactured using Atmel’s high density non-volatile memory technology. The
Flash Program memory can be reprogrammed In-System through an SPI serial interface, by a
conventional non-volatile memory programmer, or by an On-chip boot program running on the
AVR core. The boot program can use any interface to download the application program in the
Application Flash memory. Software in the Boot Flash Section will continue to run while the
Application Flash Section is updated, providing true Read-While-Write operation. By combining
an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel
ATmega8 is a powerful microcontroller that provides a highly-flexible and cost-effective solution
to many embedded control applications.
The ATmega8 AVR is supported with a full suite of program and system development tools,
including C compilers, macro assemblers, program debugger/simulators, In-Circuit Emulators,
and evaluation kits.
Disclaimer Typical values contained in this datasheet are based on simulations and characterization of
other AVR microcontrollers manufactured on the same process technology. Minimum and Maxi-
mum values will be available after the device is characterized.
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2486ZS–AVR–02/11
ATmega8(L)
Pin Descriptions
VCC Digital supply voltage.
GND Ground.
Port B (PB7..PB0)
XTAL1/XTAL2/TOSC1/
TOSC2
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port B output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscil-
lator amplifier and input to the internal clock operating circuit.
Depending on the clock selection fuse settings, PB7 can be used as output from the inverting
Oscillator amplifier.
If the Internal Calibrated RC Oscillator is used as chip clock source, PB7..6 is used as TOSC2..1
input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.
The various special features of Port B are elaborated in “Alternate Functions of Port B” on page
58 and “System Clock and Clock Options” on page 25.
Port C (PC5..PC0) Port C is an 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port C output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
PC6/RESET If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical char-
acteristics of PC6 differ from those of the other pins of Port C.
If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level on this pin
for longer than the minimum pulse length will generate a Reset, even if the clock is not running.
The minimum pulse length is given in Table 15 on page 38. Shorter pulses are not guaranteed to
generate a Reset.
The various special features of Port C are elaborated on page 61.
Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port D output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port D also serves the functions of various special features of the ATmega8 as listed on page
63.
RESET Reset input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in Table 15 on page
38. Shorter pulses are not guaranteed to generate a reset.
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2486ZS–AVR–02/11
ATmega8(L)
AVCC AVCC is the supply voltage pin for the A/D Converter, Port C (3..0), and ADC (7..6). It should be
externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be con-
nected to VCC through a low-pass filter. Note that Port C (5..4) use digital supply voltage, VCC.
AREF AREF is the analog reference pin for the A/D Converter.
ADC7..6 (TQFP and
QFN/MLF Package
Only)
In the TQFP and QFN/MLF package, ADC7..6 serve as analog inputs to the A/D converter.
These pins are powered from the analog supply and serve as 10-bit ADC channels.
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2486ZS–AVR–02/11
ATmega8(L)
Resources A comprehensive set of development tools, application notes and datasheets are available for
download on http://www.atmel.com/avr.
Note: 1.
Data Retention Reliability Qualification results show that the projected data retention failure rate is much less
than 1 PPM over 20 years at 85°C or 100 years at 25°C.
8
2486ZS–AVR–02/11
ATmega8(L)
Register Summary
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Page
0x3F (0x5F) SREG I T H S V N Z C 11
0x3E (0x5E) SPH SP10 SP9 SP8 13
0x3D (0x5D) SPL SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0 13
0x3C (0x5C) Reserved
0x3B (0x5B) GICR INT1 INT0 –– IVSEL IVCE 49, 67
0x3A (0x5A) GIFR INTF1 INTF0 67
0x39 (0x59) TIMSK OCIE2 TOIE2 TICIE1 OCIE1A OCIE1B TOIE1 TOIE0 72, 100, 119
0x38 (0x58) TIFR OCF2 TOV2 ICF1 OCF1A OCF1B TOV1 –TOV072, 101, 119
0x37 (0x57) SPMCR SPMIE RWWSB RWWSRE BLBSET PGWRT PGERS SPMEN 206
0x36 (0x56) TWCR TWINT TWEA TWSTA TWSTO TWWC TWEN –TWIE 165
0x35 (0x55) MCUCR SE SM2 SM1 SM0 ISC11 ISC10 ISC01 ISC00 33, 66
0x34 (0x54) MCUCSR –– WDRF BORF EXTRF PORF 41
0x33 (0x53) TCCR0 CS02 CS01 CS00 71
0x32 (0x52) TCNT0 Timer/Counter0 (8 Bits) 72
0x31 (0x51) OSCCAL Oscillator Calibration Register 31
0x30 (0x50) SFIOR –– ACME PUD PSR2 PSR10 58, 74, 120, 186
0x2F (0x4F) TCCR1A COM1A1 COM1A0 COM1B1 COM1B0 FOC1A FOC1B WGM11 WGM10 96
0x2E (0x4E) TCCR1B ICNC1 ICES1 WGM13 WGM12 CS12 CS11 CS10 98
0x2D (0x4D) TCNT1H Timer/Counter1 – Counter Register High byte 99
0x2C (0x4C) TCNT1L Timer/Counter1 – Counter Register Low byte 99
0x2B (0x4B) OCR1AH Timer/Counter1 – Output Compare Register A High byte 99
0x2A (0x4A) OCR1AL Timer/Counter1 – Output Compare Register A Low byte 99
0x29 (0x49) OCR1BH Timer/Counter1 – Output Compare Register B High byte 99
0x28 (0x48) OCR1BL Timer/Counter1 – Output Compare Register B Low byte 99
0x27 (0x47) ICR1H Timer/Counter1 – Input Capture Register High byte 100
0x26 (0x46) ICR1L Timer/Counter1 – Input Capture Register Low byte 100
0x25 (0x45) TCCR2 FOC2 WGM20 COM21 COM20 WGM21 CS22 CS21 CS20 114
0x24 (0x44) TCNT2 Timer/Counter2 (8 Bits) 116
0x23 (0x43) OCR2 Timer/Counter2 Output Compare Register 116
0x22 (0x42) ASSR –– AS2 TCN2UB OCR2UB TCR2UB 117
0x21 (0x41) WDTCR WDCE WDE WDP2 WDP1 WDP0 43
0x20(1) (0x40)(1) UBRRH URSEL –– UBRR[11:8] 152
UCSRC URSEL UMSEL UPM1 UPM0 USBS UCSZ1 UCSZ0 UCPOL 150
0x1F (0x3F) EEARH –EEAR8 20
0x1E (0x3E) EEARL EEAR7 EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 20
0x1D (0x3D) EEDR EEPROM Data Register 20
0x1C (0x3C) EECR –– EERIE EEMWE EEWE EERE 20
0x1B (0x3B) Reserved
0x1A (0x3A) Reserved
0x19 (0x39) Reserved
0x18 (0x38) PORTB PORTB7 PORTB6 PORTB5 PORTB4 PORTB3 PORTB2 PORTB1 PORTB0 65
0x17 (0x37) DDRB DDB7 DDB6 DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 65
0x16 (0x36) PINB PINB7 PINB6 PINB5 PINB4 PINB3 PINB2 PINB1 PINB0 65
0x15 (0x35) PORTC PORTC6 PORTC5 PORTC4 PORTC3 PORTC2 PORTC1 PORTC0 65
0x14 (0x34) DDRC DDC6 DDC5 DDC4 DDC3 DDC2 DDC1 DDC0 65
0x13 (0x33) PINC PINC6 PINC5 PINC4 PINC3 PINC2 PINC1 PINC0 65
0x12 (0x32) PORTD PORTD7 PORTD6 PORTD5 PORTD4 PORTD3 PORTD2 PORTD1 PORTD0 65
0x11 (0x31) DDRD DDD7 DDD6 DDD5 DDD4 DDD3 DDD2 DDD1 DDD0 65
0x10 (0x30) PIND PIND7 PIND6 PIND5 PIND4 PIND3 PIND2 PIND1 PIND0 65
0x0F (0x2F) SPDR SPI Data Register 127
0x0E (0x2E) SPSR SPIF WCOL –SPI2X 126
0x0D (0x2D) SPCR SPIE SPE DORD MSTR CPOL CPHA SPR1 SPR0 125
0x0C (0x2C) UDR USART I/O Data Register 148
0x0B (0x2B) UCSRA RXC TXC UDRE FE DOR PE U2X MPCM 148
0x0A (0x2A) UCSRB RXCIE TXCIE UDRIE RXEN TXEN UCSZ2 RXB8 TXB8 149
0x09 (0x29) UBRRL USART Baud Rate Register Low byte 152
0x08 (0x28) ACSR ACD ACBG ACO ACI ACIE ACIC ACIS1 ACIS0 186
0x07 (0x27) ADMUX REFS1 REFS0 ADLAR MUX3 MUX2 MUX1 MUX0 199
0x06 (0x26) ADCSRA ADEN ADSC ADFR ADIF ADIE ADPS2 ADPS1 ADPS0 200
0x05 (0x25) ADCH ADC Data Register High byte 201
0x04 (0x24) ADCL ADC Data Register Low byte 201
0x03 (0x23) TWDR Two-wire Serial Interface Data Register 167
0x02 (0x22) TWAR TWA6 TWA5 TWA4 TWA3 TWA2 TWA1 TWA0 TWGCE 167
9
2486ZS–AVR–02/11
ATmega8(L)
Notes: 1. Refer to the USART description (“USART” on page 129) for details on how to access UBRRH and UCSRC (Accessing
UBRRH/UCSRC Registers” on page 146)
2. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses
should never be written
3. Some of the Status Flags are cleared by writing a logical one to them. Note that the CBI and SBI instructions will operate on
all bits in the I/O Register, writing a one back into any flag read as set, thus clearing the flag. The CBI and SBI instructions
work with registers 0x00 to 0x1F only
0x01 (0x21) TWSR TWS7 TWS6 TWS5 TWS4 TWS3 TWPS1 TWPS0 166
0x00 (0x20) TWBR Two-wire Serial Interface Bit Rate Register 165
Register Summary (Continued)
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Page
10
2486ZS–AVR–02/11
ATmega8(L)
Instruction Set Summary
Mnemonics Operands Description Operation Flags #Clocks
ARITHMETIC AND LOGIC INSTRUCTIONS
ADD Rd, Rr Add two Registers Rd Rd + Rr Z, C, N, V, H 1
ADC Rd, Rr Add with Carry two Registers Rd Rd + Rr + C Z, C, N, V, H 1
ADIW Rdl,K Add Immediate to Word Rdh:Rdl Rdh:Rdl + K Z, C, N, V, S 2
SUB Rd, Rr Subtract two Registers Rd Rd - Rr Z, C, N, V, H 1
SUBI Rd, K Subtract Constant from Register Rd Rd - K Z, C, N, V, H 1
SBC Rd, Rr Subtract with Carry two Registers Rd Rd - Rr - C Z, C, N, V, H 1
SBCI Rd, K Subtract with Carry Constant from Reg. Rd Rd - K - C Z, C, N ,V, H 1
SBIW Rdl,K Subtract Immediate from Word Rdh:Rdl Rdh:Rdl - K Z, C, N, V, S 2
AND Rd, Rr Logical AND Registers Rd Rd Rr Z, N, V 1
ANDI Rd, K Logical AND Register and Constant Rd Rd K Z, N, V 1
OR Rd, Rr Logical OR Registers Rd Rd v Rr Z, N, V 1
ORI Rd, K Logical OR Register and Constant Rd Rd v K Z, N, V 1
EOR Rd, Rr Exclusive OR Registers Rd Rd Rr Z, N, V 1
COM Rd One’s Complement Rd 0xFF Rd Z, C, N, V 1
NEG Rd Two’s Complement Rd 0x00 Rd Z, C, N, V, H 1
SBR Rd,K Set Bit(s) in Register Rd Rd v K Z, N, V 1
CBR Rd,K Clear Bit(s) in Register Rd Rd (0xFF - K) Z, N, V 1
INC Rd Increment Rd Rd + 1 Z, N, V 1
DEC Rd Decrement Rd Rd 1 Z, N, V 1
TST Rd Test for Zero or Minus Rd Rd Rd Z, N, V 1
CLR Rd Clear Register Rd Rd Rd Z, N, V 1
SER Rd Set Register Rd 0xFF None 1
MUL Rd, Rr Multiply Unsigned R1:R0 Rd x Rr Z, C 2
MULS Rd, Rr Multiply Signed R1:R0 Rd x Rr Z, C 2
MULSU Rd, Rr Multiply Signed with Unsigned R1:R0 Rd x Rr Z, C 2
FMUL Rd, Rr Fractional Multiply Unsigned R1:R0 (Rd x Rr) << 1 Z, C 2
FMULS Rd, Rr Fractional Multiply Signed R1:R0 (Rd x Rr) << 1 Z, C 2
FMULSU Rd, Rr Fractional Multiply Signed with Unsigned R1:R0 (Rd x Rr) << 1 Z, C 2
BRANCH INSTRUCTIONS
RJMP k Relative Jump PC PC + k + 1 None 2
IJMP Indirect Jump to (Z) PC Z None 2
RCALL k Relative Subroutine Call PC PC + k + 1 None 3
ICALL Indirect Call to (Z) PC ZNone3
RET Subroutine Return PC STACK None 4
RETI Interrupt Return PC STACK I 4
CPSE Rd,Rr Compare, Skip if Equal if (Rd = Rr) PC PC + 2 or 3 None 1 / 2 / 3
CP Rd,Rr Compare Rd Rr Z, N, V, C, H 1
CPC Rd,Rr Compare with Carry Rd Rr C Z, N, V, C, H 1
CPI Rd,K Compare Register with Immediate Rd K Z, N, V, C, H 1
SBRC Rr, b Skip if Bit in Register Cleared if (Rr(b)=0) PC PC + 2 or 3 None 1 / 2 / 3
SBRS Rr, b Skip if Bit in Register is Set if (Rr(b)=1) PC PC + 2 or 3 None 1 / 2 / 3
SBIC P, b Skip if Bit in I/O Register Cleared if (P(b)=0) PC PC + 2 or 3 None 1 / 2 / 3
SBIS P, b Skip if Bit in I/O Register is Set if (P(b)=1) PC PC + 2 or 3 None 1 / 2 / 3
BRBS s, k Branch if Status Flag Set if (SREG(s) = 1) then PCPC+k + 1 None 1 / 2
BRBC s, k Branch if Status Flag Cleared if (SREG(s) = 0) then PCPC+k + 1 None 1 / 2
BREQ k Branch if Equal if (Z = 1) then PC PC + k + 1 None 1 / 2
BRNE k Branch if Not Equal if (Z = 0) then PC PC + k + 1 None 1 / 2
BRCS k Branch if Carry Set if (C = 1) then PC PC + k + 1 None 1 / 2
BRCC k Branch if Carry Cleared if (C = 0) then PC PC + k + 1 None 1 / 2
BRSH k Branch if Same or Higher if (C = 0) then PC PC + k + 1 None 1 / 2
BRLO k Branch if Lower if (C = 1) then PC PC + k + 1 None 1 / 2
BRMI k Branch if Minus if (N = 1) then PC PC + k + 1 None 1 / 2
BRPL k Branch if Plus if (N = 0) then PC PC + k + 1 None 1 / 2
BRGE k Branch if Greater or Equal, Signed if (N V= 0) then PC PC + k + 1 None 1 / 2
BRLT k Branch if Less Than Zero, Signed if (N V= 1) then PC PC + k + 1 None 1 / 2
BRHS k Branch if Half Carry Flag Set if (H = 1) then PC PC + k + 1 None 1 / 2
BRHC k Branch if Half Carry Flag Cleared if (H = 0) then PC PC + k + 1 None 1 / 2
BRTS k Branch if T Flag Set if (T = 1) then PC PC + k + 1 None 1 / 2
BRTC k Branch if T Flag Cleared if (T = 0) then PC PC + k + 1 None 1 / 2
BRVS k Branch if Overflow Flag is Set if (V = 1) then PC PC + k + 1 None 1 / 2
BRVC k Branch if Overflow Flag is Cleared if (V = 0) then PC PC + k + 1 None 1 / 2
11
2486ZS–AVR–02/11
ATmega8(L)
Mnemonics Operands Description Operation Flags #Clocks
BRIE k Branch if Interrupt Enabled if ( I = 1) then PC PC + k + 1 None 1 / 2
BRID k Branch if Interrupt Disabled if ( I = 0) then PC PC + k + 1 None 1 / 2
DATA TRANSFER INSTRUCTIONS
MOV Rd, Rr Move Between Registers Rd Rr None 1
MOVW Rd, Rr Copy Register Word Rd+1:Rd Rr+1:Rr None 1
LDI Rd, K Load Immediate Rd KNone1
LD Rd, X Load Indirect Rd (X) None 2
LD Rd, X+ Load Indirect and Post-Inc. Rd (X), X X + 1 None 2
LD Rd, - X Load Indirect and Pre-Dec. X X - 1, Rd (X) None 2
LD Rd, Y Load Indirect Rd (Y) None 2
LD Rd, Y+ Load Indirect and Post-Inc. Rd (Y), Y Y + 1 None 2
LD Rd, - Y Load Indirect and Pre-Dec. Y Y - 1, Rd (Y) None 2
LDD Rd,Y+q Load Indirect with Displacement Rd (Y + q) None 2
LD Rd, Z Load Indirect Rd (Z) None 2
LD Rd, Z+ Load Indirect and Post-Inc. Rd (Z), Z Z+1 None 2
LD Rd, -Z Load Indirect and Pre-Dec. Z Z - 1, Rd (Z) None 2
LDD Rd, Z+q Load Indirect with Displacement Rd (Z + q) None 2
LDS Rd, k Load Direct from SRAM Rd (k) None 2
ST X, Rr Store Indirect (X) Rr None 2
ST X+, Rr Store Indirect and Post-Inc. (X) Rr, X X + 1 None 2
ST - X, Rr Store Indirect and Pre-Dec. X X - 1, (X) Rr None 2
ST Y, Rr Store Indirect (Y) Rr None 2
ST Y+, Rr Store Indirect and Post-Inc. (Y) Rr, Y Y + 1 None 2
ST - Y, Rr Store Indirect and Pre-Dec. Y Y - 1, (Y) Rr None 2
STD Y+q,Rr Store Indirect with Displacement (Y + q) Rr None 2
ST Z, Rr Store Indirect (Z) Rr None 2
ST Z+, Rr Store Indirect and Post-Inc. (Z) Rr, Z Z + 1 None 2
ST -Z, Rr Store Indirect and Pre-Dec. Z Z - 1, (Z) Rr None 2
STD Z+q,Rr Store Indirect with Displacement (Z + q) Rr None 2
STS k, Rr Store Direct to SRAM (k) Rr None 2
LPM Load Program Memory R0 (Z) None 3
LPM Rd, Z Load Program Memory Rd (Z) None 3
LPM Rd, Z+ Load Program Memory and Post-Inc Rd (Z), Z Z+1 None 3
SPM Store Program Memory (Z) R1:R0 None -
IN Rd, P In Port Rd PNone1
OUT P, Rr Out Port P Rr None 1
PUSH Rr Push Register on Stack STACK Rr None 2
POP Rd Pop Register from Stack Rd STACK None 2
BIT AND BIT-TEST INSTRUCTIONS
SBI P,b Set Bit in I/O Register I/O(P,b) 1None2
CBI P,b Clear Bit in I/O Register I/O(P,b) 0None2
LSL Rd Logical Shift Left Rd(n+1) Rd(n), Rd(0) 0 Z, C, N, V 1
LSR Rd Logical Shift Right Rd(n) Rd(n+1), Rd(7) 0 Z, C, N, V 1
ROL Rd Rotate Left Through Carry Rd(0)C,Rd(n+1) Rd(n),CRd(7) Z, C, N, V 1
ROR Rd Rotate Right Through Carry Rd(7)C,Rd(n) Rd(n+1),CRd(0) Z, C, N, V 1
ASR Rd Arithmetic Shift Right Rd(n) Rd(n+1), n=0..6 Z, C, N, V 1
SWAP Rd Swap Nibbles Rd(3..0)Rd(7..4),Rd(7..4)Rd(3..0) None 1
BSET s Flag Set SREG(s) 1 SREG(s) 1
BCLR s Flag Clear SREG(s) 0 SREG(s) 1
BST Rr, b Bit Store from Register to T T Rr(b) T 1
BLD Rd, b Bit load from T to Register Rd(b) TNone1
SEC Set Carry C 1C1
CLC Clear Carry C 0 C 1
SEN Set Negative Flag N 1N1
CLN Clear Negative Flag N 0 N 1
SEZ Set Zero Flag Z 1Z1
CLZ Clear Zero Flag Z 0 Z 1
SEI Global Interrupt Enable I 1I1
CLI Global Interrupt Disable I 0 I 1
SES Set Signed Test Flag S 1S1
CLS Clear Signed Test Flag S 0 S 1
SEV Set Twos Complement Overflow. V 1V1
CLV Clear Twos Complement Overflow V 0 V 1
SET Set T in SREG T 1T1
Instruction Set Summary (Continued)
12
2486ZS–AVR–02/11
ATmega8(L)
Mnemonics Operands Description Operation Flags #Clocks
CLT Clear T in SREG T 0 T 1
SEH Set Half Carry Flag in SREG H 1H1
CLH Clear Half Carry Flag in SREG H 0 H 1
MCU CONTROL INSTRUCTIONS
NOP No Operation None 1
SLEEP Sleep (see specific descr. for Sleep function) None 1
Instruction Set Summary (Continued)
13
2486ZS–AVR–02/11
ATmega8(L)
Ordering Information
Notes: 1. This device can also be supplied in wafer form. Please contact your local Atmel sales office for detailed ordering information
and minimum quantities
2. Pb-free packaging complies to the European Directive for Restriction of Hazardous Substances (RoHS directive). Also
Halide free and fully Green
3. Tape & Reel
Speed (MHz) Power Supply (V) Ordering Code(2) Package(1) Operation Range
8 2.7 - 5.5
ATmega8L-8AU
ATmega8L-8AUR(3)
ATmega8L-8PU
ATmega8L-8MU
ATmega8L-8MUR(3)
32A
32A
28P3
32M1-A
32M1-A Industrial
(-40°C to 85°C)
16 4.5 - 5.5
ATmega8-16AU
ATmega8-16AUR(3)
ATmega8-16PU
ATmega8-16MU
ATmega8-16MUR(3)
32A
32A
28P3
32M1-A
32M1-A
Package Type
32A 32-lead, Thin (1.0mm) Plastic Quad Flat Package (TQFP)
28P3 28-lead, 0.300” Wide, Plastic Dual Inline Package (PDIP)
32M1-A 32-pad, 5 × 5 × 1.0 body, Lead Pitch 0.50mm Quad Flat No-Lead/Micro Lead Frame Package (QFN/MLF)
14
2486ZS–AVR–02/11
ATmega8(L)
Packaging Information
32A
2325 Orchard Parkway
San Jose, CA 95131
TITLE DRAWING NO.
R
REV.
32A, 32-lead, 7 x 7 mm Body Size, 1.0 mm Body Thickness,
0.8 mm Lead Pitch, Thin Profile Plastic Quad Flat Package (TQFP) C
32A
2010-10-20
PIN 1 IDENTIFIER
0°~7°
PIN 1
L
C
A1 A2 A
D1
D
eE1 E
B
Notes:
1. This package conforms to JEDEC reference MS-026, Variation ABA.
2. Dimensions D1 and E1 do not include mold protrusion. Allowable
protrusion is 0.25 mm per side. Dimensions D1 and E1 are maximum
plastic body size dimensions including mold mismatch.
3. Lead coplanarity is 0.10 mm maximum.
A 1.20
A1 0.05 0.15
A2 0.95 1.00 1.05
D 8.75 9.00 9.25
D1 6.90 7.00 7.10 Note 2
E 8.75 9.00 9.25
E1 6.90 7.00 7.10 Note 2
B 0.30 0.45
C 0.09 0.20
L 0.45 0.75
e 0.80 TYP
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN NOM MAX NOTE
15
2486ZS–AVR–02/11
ATmega8(L)
28P3
2325 Orchard Parkway
San Jose, CA 95131
TITLE DRAWING NO.
R
REV.
28P3, 28-lead (0.300"/7.62 mm Wide) Plastic Dual
Inline Package (PDIP) B
28P3
09/28/01
PIN
1
E1
A1
B
REF
E
B1
C
L
SEATING PLANE
A
0º ~ 15º
D
e
eB
B2
(4 PLACES)
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN NOM MAX NOTE
A 4.5724
A1 0.508
D 34.544 – 34.798 Note 1
E 7.620 8.255
E1 7.112 7.493 Note 1
B 0.381 0.533
B1 1.143 1.397
B2 0.762 1.143
L 3.175 3.429
C 0.203 0.356
eB 10.160
e 2.540 TYP
Note: 1. Dimensions D and E1 do not include mold Flash or Protrusion.
Mold Flash or Protrusion shall not exceed 0.25 mm (0.010").
16
2486ZS–AVR–02/11
ATmega8(L)
32M1-A
2325 Orchard Parkway
San Jose, CA 95131
TITLE DRAWING NO.
R
REV.
32M1-A, 32-pad, 5 x 5 x 1.0 mm Body, Lead Pitch 0.50 mm, E
32M1-A
5/25/06
3.10 mm Exposed Pad, Micro Lead Frame Package (MLF)
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN NOM MAX NOTE
D1
D
E1 E
e
b
A3
A2
A1
A
D2
E2
0.08 C
L
1
2
3
P
P
0
1
2
3
A 0.80 0.90 1.00
A1 0.02 0.05
A2 0.65 1.00
A3 0.20 REF
b 0.18 0.23 0.30
D
D1
D2 2.95 3.10 3.25
4.90 5.00 5.10
4.70 4.75 4.80
4.70 4.75 4.80
4.90 5.00 5.10
E
E1
E2 2.95 3.10 3.25
e 0.50 BSC
L 0.30 0.40 0.50
P 0.60
12o
Note: JEDEC Standard MO-220, Fig. 2 (Anvil Singulation), VHHD-2.
TOP VIEW
SIDE VIEW
BOTTOM VIEW
0
Pin 1 ID
Pin #1 Notch
(0.20 R)
K 0.20
K
K
17
2486ZS–AVR–02/11
ATmega8(L)
Errata The revision letter in this section refers to the revision of the ATmega8 device.
ATmega8
Rev. D to I, M
First Analog Comparator conversion may be delayed
Interrupts may be lost when writing the timer registers in the asynchronous timer
Signature may be Erased in Serial Programming Mode
CKOPT Does not Enable Internal Capacitors on XTALn/TOSCn Pins when 32KHz Oscillator is
Used to Clock the Asynchronous Timer/Counter2
Reading EEPROM by using ST or STS to set EERE bit triggers unexpected interrupt request
1. First Analog Comparator conversion may be delayed
If the device is powered by a slow rising VCC, the first Analog Comparator conversion will
take longer than expected on some devices.
Problem Fix / Workaround
When the device has been powered or reset, disable then enable theAnalog Comparator
before the first conversion.
2. Interrupts may be lost when writing the timer registers in the asynchronous timer
The interrupt will be lost if a timer register that is synchronized to the asynchronous timer
clock is written when the asynchronous Timer/Counter register(TCNTx) is 0x00.
Problem Fix / Workaround
Always check that the asynchronous Timer/Counter register neither have the value 0xFF nor
0x00 before writing to the asynchronous Timer Control Register(TCCRx), asynchronous
Timer Counter Register(TCNTx), or asynchronous Output Compare Register(OCRx).
3. Signature may be Erased in Serial Programming Mode
If the signature bytes are read before a chiperase command is completed, the signature may
be erased causing the device ID and calibration bytes to disappear. This is critical, espe-
cially, if the part is running on internal RC oscillator.
Problem Fix / Workaround:
Ensure that the chiperase command has exceeded before applying the next command.
4. CKOPT Does not Enable Internal Capacitors on XTALn/TOSCn Pins when 32KHz
Oscillator is Used to Clock the Asynchronous Timer/Counter2
When the internal RC Oscillator is used as the main clock source, it is possible to run the
Timer/Counter2 asynchronously by connecting a 32KHz Oscillator between XTAL1/TOSC1
and XTAL2/TOSC2. But when the internal RC Oscillator is selected as the main clock
source, the CKOPT Fuse does not control the internal capacitors on XTAL1/TOSC1 and
XTAL2/TOSC2. As long as there are no capacitors connected to XTAL1/TOSC1 and
XTAL2/TOSC2, safe operation of the Oscillator is not guaranteed.
Problem Fix / Workaround
Use external capacitors in the range of 20pF - 36pF on XTAL1/TOSC1 and XTAL2/TOSC2.
This will be fixed in ATmega8 Rev. G where the CKOPT Fuse will control internal capacitors
also when internal RC Oscillator is selected as main clock source. For ATmega8 Rev. G,
CKOPT = 0 (programmed) will enable the internal capacitors on XTAL1 and XTAL2. Cus-
tomers who want compatibility between Rev. G and older revisions, must ensure that
CKOPT is unprogrammed (CKOPT = 1).
18
2486ZS–AVR–02/11
ATmega8(L)
5. Reading EEPROM by using ST or STS to set EERE bit triggers unexpected interrupt
request.
Reading EEPROM by using the ST or STS command to set the EERE bit in the EECR reg-
ister triggers an unexpected EEPROM interrupt request.
Problem Fix / Workaround
Always use OUT or SBI to set EERE in EECR.
19
2486ZS–AVR–02/11
ATmega8(L)
Datasheet
Revision
History
Please note that the referring page numbers in this section are referred to this document. The
referring revision in this section are referring to the document revision.
Changes from Rev.
2486Y- 10/10 to
Rev. 2486Z- 02/11
1. Updated the datasheet according to the Atmel new Brand Style Guide.
2. Updated “Ordering Information” on page 13. Added Ording Information for
“Tape&Reel” devices
Changes from Rev.
2486X- 06/10 to
Rev. 2486Y- 10/10
1. Max Rise/Fall time in Table 102 on page 239 has been corrected from 1.6ns to 1600ns.
2. Note is added to “Performing Page Erase by SPM” on page 209.
3. Updated/corrected several short-cuts and added some new ones.
4. Updated last page according to new standard.
Changes from Rev.
2486W- 02/10 to
Rev. 2486X- 06/10
1. Updated “DC Characteristics” on page 235 with new VOL maximum value (0.9V and
0.6V).
Changes from Rev.
2486V- 05/09 to
Rev. 2486W- 02/10
1. Updated “ADC Characteristics” on page 241 with VINT maximum value (2.9V).
Changes from Rev.
2486U- 08/08 to
Rev. 2486V- 05/09
1. Updated “Errata” on page 289.
2. Updated the last page with Atmel’s new adresses.
Changes from Rev.
2486T- 05/08 to
Rev. 2486U- 08/08
1. Updated “DC Characteristics” on page 235 with ICC typical values.
Changes from Rev.
2486S- 08/07 to
Rev. 2486T- 05/08
1. Updated Table 98 on page 233.
2. Updated “Ordering Information” on page 285.
- Commercial Ordering Code removed.
- No Pb-free packaging option removed.
20
2486ZS–AVR–02/11
ATmega8(L)
Changes from Rev.
2486R- 07/07 to
Rev. 2486S- 08/07
1. Updated “Features” on page 1.
2. Added “Data Retention” on page 7.
3. Updated “Errata” on page 289.
4. Updated “Slave Mode” on page 125.
Changes from Rev.
2486Q- 10/06 to
Rev. 2486R- 07/07
1. Added text to Table 81 on page 211.
2. Fixed typo in “Peripheral Features” on page 1.
3. Updated Table 16 on page 42.
4. Updated Table 75 on page 199.
5. Removed redundancy and updated typo in Notes section of “DC Characteristics” on
page 235.
Changes from Rev.
2486P- 02/06 to
Rev. 2486Q- 10/06
1. Updated “Timer/Counter Oscillator” on page 32.
2. Updated “Fast PWM Mode” on page 88.
3. Updated code example in “USART Initialization” on page 134.
4. Updated Table 37 on page 96, Table 39 on page 97, Table 42 on page 115, Table 44 on
page 115, and Table 98 on page 233.
5. Updated “Errata” on page 289.
Changes from Rev.
2486O-10/04 to
Rev. 2486P- 02/06
1. Added “Resources” on page 7.
2. Updated “External Clock” on page 32.
3. Updated “Serial Peripheral Interface – SPI” on page 121.
4. Updated Code Example in “USART Initialization” on page 134.
5. Updated Note in “Bit Rate Generator Unit” on page 164.
6. Updated Table 98 on page 233.
7. Updated Note in Table 103 on page 241.
8. Updated “Errata” on page 289.
Changes from Rev.
2486N-09/04 to
Rev. 2486O-10/04
1. Removed to instances of “analog ground”. Replaced by “ground”.
2. Updated Table 7 on page 29, Table 15 on page 38, and Table 100 on page 237.
3. Updated “Calibrated Internal RC Oscillator” on page 30 with the 1 MHz default value.
21
2486ZS–AVR–02/11
ATmega8(L)
4. Table 89 on page 218 and Table 90 on page 218 moved to new section “Page Size” on
page 218.
5. Updated descripton for bit 4 in “Store Program Memory Control Register – SPMCR”
on page 206.
6. Updated “Ordering Information” on page 285.
Changes from Rev.
2486M-12/03 to
Rev. 2486N-09/04
1. Added note to MLF package in “Pin Configurations” on page 2.
2. Updated “Internal Voltage Reference Characteristics” on page 42.
3. Updated “DC Characteristics” on page 235.
4. ADC4 and ADC5 support 10-bit accuracy. Document updated to reflect this.
Updated features in “Analog-to-Digital Converter” on page 189.
Updated “ADC Characteristics” on page 241.
5. Removed reference to “External RC Oscillator application note” from “External RC
Oscillator” on page 28.
Changes from Rev.
2486L-10/03 to
Rev. 2486M-12/03
1. Updated “Calibrated Internal RC Oscillator” on page 30.
Changes from Rev.
2486K-08/03 to
Rev. 2486L-10/03
1. Removed “Preliminary” and TBDs from the datasheet.
2. Renamed ICP to ICP1 in the datasheet.
3. Removed instructions CALL and JMP from the datasheet.
4. Updated tRST in Table 15 on page 38, VBG in Table 16 on page 42, Table 100 on page
237 and Table 102 on page 239.
5. Replaced text “XTAL1 and XTAL2 should be left unconnected (NC)” after Table 9 in
“Calibrated Internal RC Oscillator” on page 30. Added text regarding XTAL1/XTAL2
and CKOPT Fuse in “Timer/Counter Oscillator” on page 32.
6. Updated Watchdog Timer code examples in “Timed Sequences for Changing the
Configuration of the Watchdog Timer” on page 45.
7. Removed bit 4, ADHSM, from “Special Function IO Register – SFIOR” on page 58.
8. Added note 2 to Figure 103 on page 208.
9. Updated item 4 in the “Serial Programming Algorithm” on page 231.
10. Added tWD_FUSE to Table 97 on page 232 and updated Read Calibration Byte, Byte 3, in
Table 98 on page 233.
11. Updated Absolute Maximum Ratings* and DC Characteristics in “Electrical Character-
istics” on page 235.
22
2486ZS–AVR–02/11
ATmega8(L)
Changes from Rev.
2486J-02/03 to
Rev. 2486K-08/03
1. Updated VBOT values in Table 15 on page 38.
2. Updated “ADC Characteristics” on page 241.
3. Updated “ATmega8 Typical Characteristics” on page 242.
4. Updated “Errata” on page 289.
Changes from Rev.
2486I-12/02 to Rev.
2486J-02/03
1. Improved the description of “Asynchronous Timer Clock – clkASY” on page 26.
2. Removed reference to the “Multipurpose Oscillator” application note and the “32 kHz
Crystal Oscillator” application note, which do not exist.
3. Corrected OCn waveforms in Figure 38 on page 89.
4. Various minor Timer 1 corrections.
5. Various minor TWI corrections.
6. Added note under “Filling the Temporary Buffer (Page Loading)” on page 209 about
writing to the EEPROM during an SPM Page load.
7. Removed ADHSM completely.
8. Added section “EEPROM Write during Power-down Sleep Mode” on page 23.
9. Removed XTAL1 and XTAL2 description on page 5 because they were already
described as part of “Port B (PB7..PB0) XTAL1/XTAL2/TOSC1/TOSC2” on page 5.
10. Improved the table under “SPI Timing Characteristics” on page 239 and removed the
table under “SPI Serial Programming Characteristics” on page 234.
11. Corrected PC6 in “Alternate Functions of Port C” on page 61.
12. Corrected PB6 and PB7 in “Alternate Functions of Port B” on page 58.
13. Corrected 230.4 Mbps to 230.4 kbps under “Examples of Baud Rate Setting” on page
153.
14. Added information about PWM symmetry for Timer 2 in “Phase Correct PWM Mode”
on page 111.
15. Added thick lines around accessible registers in Figure 76 on page 163.
16. Changed “will be ignored” to “must be written to zero” for unused Z-pointer bits
under “Performing a Page Write” on page 209.
17. Added note for RSTDISBL Fuse in Table 87 on page 216.
18. Updated drawings in “Packaging Information” on page 286.
23
2486ZS–AVR–02/11
ATmega8(L)
Changes from Rev.
2486H-09/02 to
Rev. 2486I-12/02
1. Added errata for Rev D, E, and F on page 289.
Changes from Rev.
2486G-09/02 to
Rev. 2486H-09/02
1. Changed the Endurance on the Flash to 10,000 Write/Erase Cycles.
Changes from Rev.
2486F-07/02 to
Rev. 2486G-09/02
1. Updated Table 103, “ADC Characteristics,” on page 241.
Changes from Rev.
2486E-06/02 to
Rev. 2486F-07/02
1. Changes in “Digital Input Enable and Sleep Modes” on page 55.
2. Addition of OCS2 in “MOSI/OC2 – Port B, Bit 3” on page 59.
3. The following tables have been updated:
Table 51, “CPOL and CPHA Functionality,” on page 127, Table 59, “UCPOL Bit Settings,”
on page 152, Table 72, “Analog Comparator Multiplexed Input(1),” on page 188, Table 73,
“ADC Conversion Time,” on page 193, Table 75, “Input Channel Selections,” on page 199,
and Table 84, “Explanation of Different Variables used in Figure 103 on page 208 and the
Mapping to the Z-pointer,” on page 214.
4. Changes in “Reading the Calibration Byte” on page 227.
5. Corrected Errors in Cross References.
Changes from Rev.
2486D-03/02 to
Rev. 2486E-06/02
1. Updated Some Preliminary Test Limits and Characterization Data
The following tables have been updated:
Table 15, “Reset Characteristics,” on page 38, Table 16, “Internal Voltage Reference Char-
acteristics,” on page 42, DC Characteristics on page 235, Table , “ADC Characteristics,” on
page 241.
2. Changes in External Clock Frequency
Added the description at the end of “External Clock” on page 32.
Added period changing data in Table 99, “External Clock Drive,” on page 237.
3. Updated TWI Chapter
More details regarding use of the TWI bit rate prescaler and a Table 65, “TWI Bit Rate Pres-
caler,” on page 167.
Changes from Rev.
2486C-03/02 to
Rev. 2486D-03/02
1. Updated Typical Start-up Times.
The following tables has been updated:
Table 5, “Start-up Times for the Crystal Oscillator Clock Selection,” on page 28, Table 6,
“Start-up Times for the Low-frequency Crystal Oscillator Clock Selection,” on page 28,
Table 8, “Start-up Times for the External RC Oscillator Clock Selection,” on page 29, and
Table 12, “Start-up Times for the External Clock Selection,” on page 32.
2. Added “ATmega8 Typical Characteristics” on page 242.
Changes from Rev.
2486B-12/01 to
Rev. 2486C-03/02
1. Updated TWI Chapter.
More details regarding use of the TWI Power-down operation and using the TWI as Master
with low TWBRR values are added into the datasheet.
Added the note at the end of the “Bit Rate Generator Unit” on page 164.
Added the description at the end of “Address Match Unit” on page 164.
2. Updated Description of OSCCAL Calibration Byte.
In the datasheet, it was not explained how to take advantage of the calibration bytes for 2, 4,
and 8 MHz Oscillator selections. This is now added in the following sections:
Improved description of “Oscillator Calibration Register – OSCCAL” on page 31 and “Cali-
bration Byte” on page 218.
3. Added Some Preliminary Test Limits and Characterization Data.
Removed some of the TBD’s in the following tables and pages:
Table 3 on page 26, Table 15 on page 38, Table 16 on page 42, Table 17 on page 44, “TA =
-40°C to +85°C, VCC = 2.7V to 5.5V (unless otherwise noted)” on page 235, Table 99 on
page 237, and Table 102 on page 239.
4. Updated Programming Figures.
Figure 104 on page 219 and Figure 112 on page 230 are updated to also reflect that AVCC
must be connected during Programming mode.
5. Added a Description on how to Enter Parallel Programming Mode if RESET Pin is Dis-
abled or if External Oscillators are Selected.
Added a note in section “Enter Programming Mode” on page 221.
2486ZS–AVR–02/11
Atmel Corporation
2325 Orchard Parkway
San Jose, CA 95131
USA
Tel: (+1)(408) 441-0311
Fax: (+1)(408) 487-2600
www.atmel.com
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