BoardPilotArduino Mega 2560 R3 pinout
A big Arduino with 54 digital pins, 16 analog inputs and 4 serial ports. It uses 5 V logic, so 3.3 V-only sensors need a level shifter.
At a glance
- Chip
- ATmega2560
- Processor
- 8-bit AVR ATmega2560 at 16 MHz, 8 KB SRAM, 256 KB flash, 4 KB EEPROM
- Logic level
- 5 V. 3.3 V-only sensors need a level shifter.
- Flashing tool
- avrdude
- Arduino board (FQBN)
- arduino:avr:mega
- Live pin view in BoardPilot
- Yes (diagnostic agent available)
Pins to avoid or use with care
USB serial: TX0→1 (PE1), RX0←0 (PE0)
Used for uploading and the serial monitor. Anything connected here can break uploads.
Good pins for LEDs, buttons and signals
22, 23, 24, 25, 26, 27, 28, 29, ~2, ~3, ~4, ~5, ~6, ~7, ~8, ~9
Default pins in Arduino
- I2C
- SDA = SDA 20, SCL = SCL 21. Only these pins work with the Wire library defaults. I2C only works on 20 (SDA) and 21 (SCL); the SDA/SCL pins near AREF are the same signals. Both have 10 kΩ pull-ups to 5 V on the board.
- SPI
- MOSI = 51, MISO = 50, SCK = 52, CS = 53.
- Analog inputs
- A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15 (0–5 V)
All 85 pins
| Pin | GPIO | Chip pin | Functions | Notes |
|---|---|---|---|---|
| SCL | 21 | PD0 | GPIO, I2C_SCL (default), INT0 | Same signal as D21 (I2C clock). Has a 10 kΩ pull-up to 5 V on the board: 3.3 V-only I2C parts need a level shifter. |
| SDA | 20 | PD1 | GPIO, I2C_SDA (default), INT1 | Same signal as D20 (I2C data). Has a 10 kΩ pull-up to 5 V on the board: 3.3 V-only I2C parts need a level shifter. |
| AREF | — | ADC_REF | Analog reference input. Leave it unconnected unless your code calls analogReference(EXTERNAL); never power parts from it. | |
| GND | — | |||
| ~13 | 13 | PB7 | GPIO, PWM | The built-in LED "L" is on this pin. |
| ~12 | 12 | PB6 | GPIO, PWM | |
| ~11 | 11 | PB5 | GPIO, PWM | |
| ~10 | 10 | PB4 | GPIO, PWM | |
| ~9 | 9 | PH6 | GPIO, PWM | |
| ~8 | 8 | PH5 | GPIO, PWM | |
| ~7 | 7 | PH4 | GPIO, PWM | |
| ~6 | 6 | PH3 | GPIO, PWM | |
| ~5 | 5 | PE3 | GPIO, PWM | |
| ~4 | 4 | PG5 | GPIO, PWM | |
| ~3 | 3 | PE5 | GPIO, INT5, PWM | |
| ~2 | 2 | PE4 | GPIO, INT4, PWM | |
| TX0→1 | 1 | PE1 | GPIO, UART0_TX | Serial TX. Shared with the USB link: using it for parts can break uploads and the serial monitor. |
| RX0←0 | 0 | PE0 | GPIO, UART0_RX | Serial RX. Shared with the USB link: using it for parts can break uploads and the serial monitor. |
| TX3 14 | 14 | PJ1 | GPIO, UART3_TX | |
| RX3 15 | 15 | PJ0 | GPIO, UART3_RX | |
| TX2 16 | 16 | PH1 | GPIO, UART2_TX | |
| RX2 17 | 17 | PH0 | GPIO, UART2_RX | |
| TX1 18 | 18 | PD3 | GPIO, UART1_TX, INT3 | |
| RX1 19 | 19 | PD2 | GPIO, UART1_RX, INT2 | |
| SDA 20 | 20 | PD1 | GPIO, I2C_SDA (default), INT1 | Default I2C SDA. Has a 10 kΩ pull-up to 5 V on the board: 3.3 V-only I2C parts need a level shifter. |
| SCL 21 | 21 | PD0 | GPIO, I2C_SCL (default), INT0 | Default I2C SCL. Has a 10 kΩ pull-up to 5 V on the board: 3.3 V-only I2C parts need a level shifter. |
| IOREF | — | Tells shields that this board uses 5 V logic. Connected to 5V; not meant to power parts. | ||
| RESET | — | RESET | Reset input. Pull it LOW (or press the button) to restart the board. | |
| 3.3V | — | 3.3 V output, 50 mA max. Enough for one or two small sensors. | ||
| 5V | — | 5 V output from USB or the on-board regulator. | ||
| GND | — | |||
| GND | — | |||
| Vin | — | Power input (7-12 V recommended) from the barrel jack or an external supply. It is not fed from USB, so do not use it to power parts. | ||
| A0 | 54 | PF0 | GPIO, ADC0 | |
| A1 | 55 | PF1 | GPIO, ADC1 | |
| A2 | 56 | PF2 | GPIO, ADC2 | |
| A3 | 57 | PF3 | GPIO, ADC3 | |
| A4 | 58 | PF4 | GPIO, ADC4 | |
| A5 | 59 | PF5 | GPIO, ADC5 | |
| A6 | 60 | PF6 | GPIO, ADC6 | |
| A7 | 61 | PF7 | GPIO, ADC7 | |
| A8 | 62 | PK0 | GPIO, ADC8 | |
| A9 | 63 | PK1 | GPIO, ADC9 | |
| A10 | 64 | PK2 | GPIO, ADC10 | |
| A11 | 65 | PK3 | GPIO, ADC11 | |
| A12 | 66 | PK4 | GPIO, ADC12 | |
| A13 | 67 | PK5 | GPIO, ADC13 | |
| A14 | 68 | PK6 | GPIO, ADC14 | |
| A15 | 69 | PK7 | GPIO, ADC15 | |
| 5V | — | 5 V, same rail as the 5V pin. | ||
| 5V | — | 5 V, same rail as the 5V pin. | ||
| 22 | 22 | PA0 | GPIO | |
| 23 | 23 | PA1 | GPIO | |
| 24 | 24 | PA2 | GPIO | |
| 25 | 25 | PA3 | GPIO | |
| 26 | 26 | PA4 | GPIO | |
| 27 | 27 | PA5 | GPIO | |
| 28 | 28 | PA6 | GPIO | |
| 29 | 29 | PA7 | GPIO | |
| 30 | 30 | PC7 | GPIO | |
| 31 | 31 | PC6 | GPIO | |
| 32 | 32 | PC5 | GPIO | |
| 33 | 33 | PC4 | GPIO | |
| 34 | 34 | PC3 | GPIO | |
| 35 | 35 | PC2 | GPIO | |
| 36 | 36 | PC1 | GPIO | |
| 37 | 37 | PC0 | GPIO | |
| 38 | 38 | PD7 | GPIO | |
| 39 | 39 | PG2 | GPIO | |
| 40 | 40 | PG1 | GPIO | |
| 41 | 41 | PG0 | GPIO | |
| 42 | 42 | PL7 | GPIO | |
| 43 | 43 | PL6 | GPIO | |
| 44 | 44 | PL5 | GPIO, PWM | |
| 45 | 45 | PL4 | GPIO, PWM | |
| 46 | 46 | PL3 | GPIO, PWM | |
| 47 | 47 | PL2 | GPIO | |
| 48 | 48 | PL1 | GPIO | |
| 49 | 49 | PL0 | GPIO | |
| 50 | 50 | PB3 | GPIO, SPI_MISO (default) | |
| 51 | 51 | PB2 | GPIO, SPI_MOSI (default) | |
| 52 | 52 | PB1 | GPIO, SPI_SCK (default) | |
| 53 | 53 | PB0 | GPIO, SPI_CS (default) | SPI chip select. Keep it an OUTPUT when using SPI, or SPI can stop working. |
| GND | — | |||
| GND | — |
Check your wiring with BoardPilot
BoardPilot shows this board in 3D, flags risky pins as you wire, and flashes it safely with a backup first.
Download BoardPilotSources
- Arduino MEGA 2560 Rev3 Eagle design files, Board outline; header pads and nets (POWER, ADCL, ADCH, JP6, PWML, COMMUNICATION, XIO); RN1 10k pull-ups on SDA/SCL
- Arduino Mega 2560 Rev3 datasheet (A000067), Connector pinouts; IOREF connected to 5V; VIN 7-12 V
- Arduino Mega 2560 Rev3 full pinout (A000067)
- Microchip ATmega640/1280/1281/2560/2561 datasheet, 1 Pin Configurations; 13.3 Alternate Port Functions; 15 External Interrupts; 26 ADC
- arduino/ArduinoCore-avr variants/mega/pins_arduino.h, Arduino pin to port table, PWM timers, SPI/I2C defaults, A0 = 54
- arduino/ArduinoCore-avr boards.txt, USB VID/PID, upload protocol wiring at 115200
- Board data file and source notes on GitHub