Atmega16 Pin Diagram And Explanation

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• MOSI (Master Out Slave In)
• MISO (Master In Slave Out)
• SCK (Serial Clock)
• RESET
• GND (Ground)
Now connect the power supplies that are Vcc and GND to the micro controller.
Vcc = +5V and GND = 0V
Do not forget to connect Reset to Vcc with a 1K/10K resistor for pulling up. That is it we are ready with the hardware.
ATmega16 has 16 KB programmable flash memory, static RAM of 1 KB and EEPROM of 512 Bytes. 

Pin No.	Pin name	Description	Alternate Function
1	(XCK/T0) PB0	I/O PORTB, Pin 0	T0: Timer0 External Counter Input. XCK : USART External Clock I/O
2	(T1) PB1	I/O PORTB, Pin 1	T1:Timer1 External Counter Input
3	(INT2/AIN0) PB2	I/O PORTB, Pin 2	AIN0: Analog Comparator Positive I/P INT2: External Interrupt 2 Input
4	(OC0/AIN1) PB3	I/O PORTB, Pin 3	AIN1: Analog Comparator Negative I/P OC0 : Timer0 Output Compare Match Output
5	(SS) PB4	I/O PORTB, Pin 4	In System Programmer (ISP) Serial Peripheral Interface (SPI)
6	(MOSI) PB5	I/O PORTB, Pin 5
7	(MISO) PB6	I/O PORTB, Pin 6
8	(SCK) PB7	I/O PORTB, Pin 7
9	RESET	Reset Pin, Active Low Reset
10	Vcc	Vcc = +5V
11	GND	GROUND
12	XTAL2	Output to Inverting Oscillator Amplifier
13	XTAL1	Input to Inverting Oscillator Amplifier
14	(RXD) PD0	I/O PORTD, Pin 0	USART Serial Communication Interface
15	(TXD) PD1	I/O PORTD, Pin 1
16	(INT0) PD2	I/O PORTD, Pin 2	External Interrupt INT0
17	(INT1) PD3	I/O PORTD, Pin 3	External Interrupt INT1
18	(OC1B) PD4	I/O PORTD, Pin 4	PWM Channel Outputs
19	(OC1A) PD5	I/O PORTD, Pin 5
20	(ICP) PD6	I/O PORTD, Pin 6	Timer/Counter1 Input Capture Pin
21	PD7 (OC2)	I/O PORTD, Pin 7	Timer/Counter2 Output Compare Match Output
22	PC0 (SCL)	I/O PORTC, Pin 0	TWI Interface
23	PC1 (SDA)	I/O PORTC, Pin 1
24	PC2 (TCK)	I/O PORTC, Pin 2	JTAG Interface
25	PC3 (TMS)	I/O PORTC, Pin 3
26	PC4 (TDO)	I/O PORTC, Pin 4
27	PC5 (TDI)	I/O PORTC, Pin 5
28	PC6 (TOSC1)	I/O PORTC, Pin 6	Timer Oscillator Pin 1
29	PC7 (TOSC2)	I/O PORTC, Pin 7	Timer Oscillator Pin 2
30	AVcc	Voltage Supply = Vcc for ADC
31	GND	GROUND
32	AREF	Analog Reference Pin for ADC
33	PA7 (ADC7)	I/O PORTA, Pin 7	ADC Channel 7
34	PA6 (ADC6)	I/O PORTA, Pin 6	ADC Channel 6
35	PA5 (ADC5)	I/O PORTA, Pin 5	ADC Channel 5
36	PA4 (ADC4)	I/O PORTA, Pin 4	ADC Channel 4
37	PA3 (ADC3)	I/O PORTA, Pin 3	ADC Channel 3
38	PA2 (ADC2)	I/O PORTA, Pin 2	ADC Channel 2
39	PA1 (ADC1)	I/O PORTA, Pin 1	ADC Channel 1
40	PA0 (ADC0)	I/O PORTA, Pin 0	ADC Channel 0

Port A (PA7 ‐ PA0): Port A serves as the analog inputs to the A/D Converter. Port A also serves as an 8‐bit bi‐directional I/O port, if the A/D Converter is not used. When pins PA0 to PA7 are used as inputs and are externally pulled low, they will source current if the internal pull‐up resistors are activated. The Port A pins are tri‐stated when a reset condition becomes active, even if the clock is not running.

Port B (PB7 ‐ PB0): Port B is an 8‐bit bi‐directional I/O port with internal pull‐up resistors (selected for each bit). Port B also serves the functions of various special features of the ATmega16 as listed on page 58 of datasheet.

Port C (PC7 ‐ PC0): Port C is an 8‐bit bi‐directional I/O port with internal pull‐up resistors (selected for each bit). Port C also serves the functions of the JTAG interface and other special features of the ATmega16 as listed on page 61 of datasheet. If the JTAG interface is enabled, the pull‐up resistors on pins PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.

Port D (PD7 ‐ PD0): Port D is an 8‐bit bi‐directional I/O port with internal pull‐up resistors (selected for each bit). Port D also serves the functions of various special features of the ATmega16 as listed on page 63 of datasheet.

RESET: Reset Input. A low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock is not running.

XTAL1: External oscillator pin 1

XTAL2: External oscillator pin 2

41

AVCC: AVCC is the supply voltage pin for Port A and the A/D Converter. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low‐pass filter.

AREF: AREF is the analog reference pin for the A/D Converter.

You can see it has 32 I/O (Input/output) pins grouped as A, B, C & D with 8 pins in each group. This group is called as PORT.

• PA0 ‐ PA7 (PORTA)

• PB0 ‐ PB7 (PORTB)

• PC0 ‐ PC7 (PORTC)

• PD0 ‐ PD7 (PORTD)

Notice that all these pins have some function written in bracket. These are additional function that pin can perform other than I/O. Some of them are.

• ADC (ADC0 ‐ ADC7 on PORTA)

• UART (Rx,Tx on PORTD)

• TIMERS (OC0 ‐ OC2)

• SPI (MISO, MOSI, SCK on PORTB)

• External Interrupts (INT0 ‐ INT2)