ATmega8A Atmel Corporation, ATmega8A Datasheet - Page 58

• Manufacturer Part Number: ATmega8A
• Manufacturer: Atmel Corporation

Specifications of ATmega8A

• 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
• Pwm Channels: 3
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

12.3.2
8159D–AVR–02/11
Alternate Functions of Port B
The Port B pins with alternate functions are shown in
Table 12-2.
The alternate pin configuration is as follows:
• XTAL2/TOSC2 – Port B, Bit 7
XTAL2: Chip clock Oscillator pin 2. Used as clock pin for crystal Oscillator or Low-frequency
crystal Oscillator. When used as a clock pin, the pin can not be used as an I/O pin.
TOSC2: Timer Oscillator pin 2. Used only if internal calibrated RC Oscillator is selected as chip
clock source, and the asynchronous timer is enabled by the correct setting in ASSR. When the
AS2 bit in ASSR is set (one) to enable asynchronous clocking of Timer/Counter2, pin PB7 is dis-
connected from the port, and becomes the inverting output of the Oscillator amplifier. In this
mode, a crystal Oscillator is connected to this pin, and the pin cannot be used as an I/O pin.
If PB7 is used as a clock pin, DDB7, PORTB7 and PINB7 will all read 0.
• XTAL1/TOSC1 – Port B, Bit 6
XTAL1: Chip clock Oscillator pin 1. Used for all chip clock sources except internal calibrated RC
Oscillator. When used as a clock pin, the pin can not be used as an I/O pin.
TOSC1: Timer Oscillator pin 1. Used only if internal calibrated RC Oscillator is selected as chip
clock source, and the asynchronous timer is enabled by the correct setting in ASSR. When the
AS2 bit in ASSR is set (one) to enable asynchronous clocking of Timer/Counter2, pin PB6 is dis-
connected from the port, and becomes the input of the inverting Oscillator amplifier. In this
mode, a crystal Oscillator is connected to this pin, and the pin can not be used as an I/O pin.
If PB6 is used as a clock pin, DDB6, PORTB6 and PINB6 will all read 0.
• SCK – Port B, Bit 5
SCK: Master Clock output, Slave Clock input pin for SPI channel. When the SPI is enabled as a
Slave, this pin is configured as an input regardless of the setting of DDB5. When the SPI is
enabled as a Master, the data direction of this pin is controlled by DDB5. When the pin is forced
by the SPI to be an input, the pull-up can still be controlled by the PORTB5 bit.
Port Pin
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
Port B Pins Alternate Functions
Alternate Functions
XTAL2 (
TOSC2 (
XTAL1 (
TOSC1 (
SCK (SPI Bus Master clock Input)
MOSI (SPI Bus Master Output/Slave Input)
OC2 (Timer/Counter2 Output Compare Match Output)
SS (SPI Bus Master Slave select)
OC1B (Timer/Counter1 Output Compare Match B Output)
OC1A (Timer/Counter1 Output Compare Match A Output)
ICP1 (Timer/Counter1 Input Capture Pin)
MISO (SPI Bus Master Input/Slave Output)
Chip Clock Oscillator pin 2
Chip Clock Oscillator pin 1 or External clock input
Timer Oscillator pin 2
Timer Oscillator pin 1
)
)
)
Table
12-2.
)
ATmega8A
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