Why use ATmega??

Well students mostly use either a ATmega8, ATmega16/32 cause they are very very cheap. Their development board can be home processed/fabricated very easily. As can be seen from the figure, the ATmega16 has external connections for power supplies (VCC, GND, AVCC, and AREF), an external time base (XTAL1 and XTAL2) input pins to drive its clocks, processor reset (active low RESET), and four 8-bit ports (PA0-PA7, PC0-PC7, PB0-PB7, and PD0-PD7), which are used to interact with the external world. As we shall soon see, these ports may be used as general purpose digital input/output (I/O) ports or they may be used for the alternate functions. The ports are interconnected with the ATmega16’s CPU and internal subsystems via an internal bus.The ATmega16 also contains a timer subsystem, an analog-to-digital converter (ADC), an interrupt subsystem, memory components, and a communication subsystem.