Manual Atmega8

Features
• High-performance, Low-power AVR® 8-bit Microcontroller
• Advanced RISC Architecture

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– 130 Powerful Instructions – Most Single-clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Fully Static Operation
– Up to 16 MIPS Throughput at 16 MHz
– On-chip 2-cycle Multiplier
Nonvolatile Program and Data Memories
– 8K Bytes of In-SystemSelf-Programmable Flash
Endurance: 10,000 Write/Erase Cycles
– Optional Boot Code Section with Independent Lock Bits
In-System Programming by On-chip Boot Program
True Read-While-Write Operation
– 512 Bytes EEPROM
Endurance: 100,000 Write/Erase Cycles
– 1K Byte Internal SRAM
– Programming Lock for Software Security
Peripheral Features
– Two 8-bit Timer/Counters with Separate Prescaler, oneCompare 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 MLF package
Eight Channels 10-bit Accuracy
– 6-channel ADC in PDIP package
Eight Channels 10-bit Accuracy
– Byte-oriented Two-wire Serial Interface
– Programmable Serial USART
– Master/Slave SPISerial 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/OLines
– 28-lead PDIP, 32-lead TQFP, and 32-pad MLF
Operating Voltages
– 2.7 - 5.5V (ATmega8L)
– 4.5 - 5.5V (ATmega8)
Speed Grades
– 0 - 8 MHz (ATmega8L)
– 0 - 16 MHz (ATmega8)
Power Consumption at 4 Mhz, 3V, 25°C
– Active: 3.6 mA
– Idle Mode: 1.0 mA
– Power-down Mode: 0.5 µA

8-bit
with 8K Bytes
In-System
Programmable
Flash
ATmega8
ATmega8L

2486O–AVR–10/04

PinConfigurations
PDIP
(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

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

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)

32
31
30
29
28
27
26
25

PD2 (INT0)
PD1 (TXD)
PD0 (RXD)
PC6 (RESET)
PC5 (ADC5/SCL)
PC4 (ADC4/SDA)
PC3 (ADC3)
PC2 (ADC2)

TQFP Top View

24
23
22
21
20
19
18
17

PC1 (ADC1)
PC0 (ADC0)
ADC7
GND
AREF
ADC6
AVCC
PB5 (SCK)

24
23
22
21
20
19
18
17

1
2
3
4
5
6
7
8

PC1 (ADC1)
PC0 (ADC0)
ADC7GND
AREF
ADC6
AVCC
PB5 (SCK)

(T1) PD5
(AIN0) PD6
(AIN1) PD7
(ICP1) PB0
(OC1A) PB1
(SS/OC1B) PB2
(MOSI/OC2) PB3
(MISO) PB4

9
10
11
12
13
14
15
16

(INT1) PD3
(XCK/T0) PD4
GND
VCC
GND
VCC
(XTAL1/TOSC1) PB6
(XTAL2/TOSC2) PB7

32
31
30
29
28
27
26
25

PD2 (INT0)
PD1 (TXD)
PD0 (RXD)
PC6 (RESET)
PC5 (ADC5/SCL)
PC4 (ADC4/SDA)
PC3 (ADC3)
PC2 (ADC2)

MLFTop View

1
2
3
4
5
6
7
8

(T1) PD5
(AIN0) PD6
(AIN1) PD7
(ICP1) PB0
(OC1A) PB1
(SS/OC1B) PB2
(MOSI/OC2) PB3
(MISO) PB4

9
10
11
12
13
14
15
16

(INT1) PD3
(XCK/T0) PD4
GND
VCC
GND
VCC
(XTAL1/TOSC1) PB6
(XTAL2/TOSC2) PB7

2

NOTE:
The large center pad underneath the MLF
packages is made of metal and internally
connected to GND. It should be soldered
orglued to the PCB to ensure good
mechanical stability. If the center pad is
left unconneted, the package might
loosen from the PCB.

ATmega8(L)
2486O–AVR–10/04

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...