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 ...

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