ATmega8 Atmel Corporation, ATmega8 Datasheet - Page 17

• Manufacturer Part Number: ATmega8
• Manufacturer: Atmel Corporation

Specifications of ATmega8

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 2
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Errata
ATmega8
Rev. D to I, M
2486ZS–AVR–02/11
The revision letter in this section refers to the revision of the ATmega8 device.
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1. First Analog Comparator conversion may be delayed
2. Interrupts may be lost when writing the timer registers in the asynchronous timer
3. Signature may be Erased in Serial Programming Mode
4. CKOPT Does not Enable Internal Capacitors on XTALn/TOSCn Pins when 32KHz
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
If the device is powered by a slow rising V
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.
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.
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).
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.
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).
Problem Fix / Workaround
CC
, the first Analog Comparator conversion will
ATmega8(L)
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