AVR Introduction

ATmega16 is an 8-bit microcontroller.

  • ATmega16 is based on RISC architecture.
  • It is a 40pin microcontroller.
  • ATmega16 has various in-built peripherals like USART,ADC,SPI,JTAG.
  • It has 16kb programmable flash memory,static RAM of 1kb.
  • It has EEPROM of 512 Bytes.

Pin Diagram


  • Most of these pins are used to connect to I/O devices.
  • Four I/O port take 32 pins.
  • Port A, Port B, Port C, Port D.
  • Each port have 8 pins.


  • PIN1 :I/O , T0 ( Timer0 External Counter Input) ,XCK : USART External Clock I/O.
  • PIN2 :I/O, T1 (Timer1 External Counter Input) .
  • PIN3 :I/O, AIN0: Analog Comparator Positive Input ,INT2: External Interrupt 2 Input.
  • PIN4 :I/O, AIN1: Analog Comparator Negative Input,OC0 : Timer0 Output Compare Match Output.
  • PIN9 :Reset Pin, Active Low Reset.


  • PIN10 :VCC=+5V.
  • PIN11 :GND.
  • PIN12 :XTAL2.
  • PIN13 :XTAL1.
  • PIN14 :(RXD) ,I/O PIN 0,USART Serial Communication Interface.
  • PIN15 :(TXD) ,I/O Pin 1,USART Serial Communication Interface.
  • PIN16 :(INT0),I/O Pin 2,External Interrupt INT0.
  • PIN17 :(INT1),I/O Pin 3,External Interrupt INT1.
  • PIN18 :(OC1B),I/O Pin 4,PWM Channel Outputs.
  • PIN19 :(OC1A),I/O Pin 5,PWM Channel Outputs.
  • PIN20 :(ICP),I/O Pin 6,Timer/Counter1 Input Capture Pin.
  • PIN21 :(OC2),I/O Pin 7,Timer/Counter2 Output Compare Match Output.
  • PIN22 :(SCL),I/O Pin 0,TWI Interface.
  • PIN23 :(SDA),I/O Pin 1,TWI Interface.
  • PIN28 :(TOSC1),I/O Pin 6,Timer Oscillator Pin 1.
  • PIN29 :(TOSC2),I/O Pin 7,Timer Oscillator Pin 2.
  • PIN30 :AVCC (for ADC).
  • PIN31 :GND (for ADC).
  • PIN33 :PIN40PAx: I/O,ADCx (Where x is 7 to 0).