Arduino Cookbook

Appendix F. Digital and Analog Pins

Tables F-1 and F-2 show the digital and analog pins for a standard Arduino board and the Mega board.

The “Port” column lists the physical port used for the pin—see Recipe 18.11 for information on how to set a pin by writing directly to a port. The introduction to Chapter 18 contains more details on timer usage.

Table F-1. Analog and digital pin assignments common to popular Arduino boards

Digital pin	Arduino 168/328			Arduino Mega (pins 0–19)
	Port	Analog pin	Usage	Port	Analog pin	Usage
0	PD 0		USART RX	PE 0		USART0 RX, Pin Int 8
1	PD 1		USART TX	PE 1		USART0 TX
2	PD 2		Ext Int 0	PE 4		PWM T3B, INT4
3	PD 3		PWM T2B, Ext Int 1	PE 5		PWM T3C, INT5
4	PD 4			PG 5		PWM T0B
5	PD 5		PWM T0B	PE 3		PWM T3A
6	PD 6		PWM T0A	PH 3		PWM T4A
7	PD 7			PH 4		PWM T4B
8	PB 0		Input capture	PH 5		PWM T4C
9	PB 1		PWM T1A	PH 6		PWM T2B
10	PB 2		PWM T1B, SS	PB 4		PWM T2A, Pin Int 4
11	PB 3		PWM T2A, MOSI	PB 5		PWM T1A, Pin Int 5
12	PB 4		SPI MISO	PB 6		PWM T1B, Pin Int 6
13	PB 5		SPI SCK	PB 7		PWM T0A, Pin Int 7
14	PC 0	0		PJ 1		USART3 TX, Pin Int 10
15	PC 1	1		PJ 0		USART3 RX, Pin Int 9
16	PC 2	2		PH 1		USART2 TX
17	PC 3	3		PH 0		USART2 RX
18	PC 4	4	I2C SDA	PD 3		USART1 TX, Ext Int 3
19	PC 5	5	I2C SCL	PD 2		USART1 RX, Ext Int 2

Table F-2. Assignments for additional Mega pins

Arduino Mega (pins 20–44)			Arduino Mega (pins 45–69)
Digital pin	Port	Usage	Digital pin	Port	Analog pin	Usage
20	PD 1	I2C SDA, Ext Int 1	45	PL 4		PWM 5B
21	PD 0	I2C SCL, Ext Int 0	46	PL 3		PWM 5A
22	PA 0	Ext Memory addr bit 0	47	PL 2		T5 external counter
23	PA 1	Ext Memory bit 1	48	PL 1		ICP T5
24	PA 2	Ext Memory bit 2	49	PL 0		ICP T4
25	PA 3	Ext Memory ...