Atmel ATmega8 User manual

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 16MIPS 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 Atmel with

8KBytes In-

System

Programmable

Flash

ATmega8

ATmega8L

Summary

Rev.2486AAS–AVR–02/2013

2486AAS–AVR–02/2013

ATmega8(L)

Configurations

(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)

TQFP Top View

(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

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.

2486AAS–AVR–02/2013

ATmega8(L)

Overview The Atmel®AVR®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 1MIPS per MHz, allowing the system designer to optimize power con-

sumption versus processing speed.

Block Diagram Figure 1. Block Diagram

INTERNAL

OSCILLATOR

WATCHDOG

TIMER

MCU CTRL.

& TIMING

OSCILLATOR

TIMERS/

COUNTERS

INTERRUPT

UNIT

STACK

POINTER

EEPROM

SRAM

STATUS

USART

PROGRAM

COUNTER

PROGRAM

FLASH

INSTRUCTION

DECODER

PROGRAMMING

LOGIC

SPI

ADC

INTERFACE

COMP.

INTERFACE

PORTC DRIVERS/BUFFERS

PORTC DIGITAL INTERFACE

GENERAL

PURPOSE

REGISTERS

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

2486AAS–AVR–02/2013

ATmega8(L)

The Atmel®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 inde-

pendent 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 conventional 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 is supported with a full suite of program and system development tools, including

C compilers, macro assemblers, program simulators, 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.

2486AAS–AVR–02/2013

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.

2486AAS–AVR–02/2013

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

4. See characterization specification at 105C

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

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

28P3

32M1-A

8 2.7 - 5.5

ATmega8L-8AN

ATmega8L-8ANR(3)

ATmega8L-8PN

ATmega8L-8MN

ATmega8L-8MUR(3)

32A

28P3

32M1-A

32M1-A Industrial

(-40C to 105C)

16 4.5 - 5.5

ATmega8-16AN

ATmega8-16ANR(3)

ATmega8-16PN

ATmega8-16MN

ATmega8-16MUR(3)

32A

28P3

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)

2486AAS–AVR–02/2013

ATmega8(L)

Packaging Information

32A

TITLE DRAWING NO. REV.

32A, 32-lead, 7 x 7mm body size, 1.0mm body thickness,

0.8mm lead pitch, thin prole plastic quad at package (TQFP) C

32A

2010-10-20

PIN 1 IDENTIFIER

0°~7°

PIN 1

A1 A2 A

eE1 E

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 0.25mm per side. Dimensions D1 and E1 are maximum

plastic body size dimensions including mold mismatch.

3. Lead coplanarity is 0.10mm 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

2486AAS–AVR–02/2013

ATmega8(L)

28P3

2325 Orchard Parkway

San Jose, CA 95131

TITLE DRAWING NO.

REV.

28P3, 28-lead (0.300"/7.62mm Wide) Plastic Dual

Inline Package (PDIP) B

28P3

09/28/01

REF

SEATING PLANE

0º ~ 15º

(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 0.25mm (0.010").

2486AAS–AVR–02/2013

ATmega8(L)

32M1-A

2325 Orchard Parkway

San Jose, CA 95131

TITLE DRAWING NO.

REV.

32M1-A, 32-pad, 5 x 5 x 1.0mm Body, Lead Pitch 0.50mm, E

32M1-A

5/25/06

3.10mm Exposed Pad, Micro Lead Frame Package (MLF)

COMMON DIMENSIONS

(Unit of Measure = mm)

SYMBOL MIN NOM MAX NOTE

E1 E

0.08 C

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

D2 2.95 3.10 3.25

4.90 5.00 5.10

4.70 4.75 4.80

4.90 5.00 5.10

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

Pin 1 ID

Pin #1 Notch

(0.20 R)

K 0.20 – –

2486AAS–AVR–02/2013

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).

This manual suits for next models

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