In this article described the hardware features of the AVR ATMega atmega 8 that is devoted to the type of PDIP, so for other types (QFN / MLF, TQPF) please refer to the specific datasheet only.
In addition to functioning as an input/output pins, a pin on AVR microcontroller can concurrently as other functions. For example at the AVR ATMega 8 microcontroller, PORTD.2 is an input / output pins, but this pin can also function as a trigger channel “external interrupt 0”. For more details, please follow the following explanation:
Description pin features on ATMega 8:
-VCC: supply voltage Microcontroller
– Port B is a port i / o 8bit with internal pull-up resistors on each pin.
– Buffer on port B AVR ATMega8 have the capacity to absorb (sink) and distribute (sorce)
– Lodging in PB.6 can be used as a crystal input (inverting oscillator amplifier) and input to the internal clock circuit depends on the setting of fuse bits (currently set software downloader / programmer) is used as a clock source.
– Especially for PB.7 port can be used as a crystal output (inverting oscillator amplifier output) depends upon the setting of fuse bits are used to select the clock source.
– If the clock source is the internal oscillator (internal clock, then PB6 and PB7 pin can be used as input / output (I / O pin) or if using Asyncronousu Timer / Counter2 then PB6 and PB7 (TOSC2 and TOSC1) used for counter input channels.
– PORTC.0 – PORTC.5 are input / output ports with internal pull-up resistor for each pin. Buffer in this PORT has the capacity to absorb (sink) and distribute (sorce). In addition, the PORTC in atmega8 microcontroller can function as port ADC (analog to digital converter).
– Reset / PORTC.6, is a pin that can function as a reset pin on the microcontroller program cycle. By way RSTDISBL fuse bit set as “unprogramed” and will be active when it gets a signal “low”. But if RSTDISBL set as “programed” then portC.6 will be used as input / usual output pins.