Arduino Micro Pinout

Arduino Micro is a small board (48 × 18 mm) with the ATmega32U4 chip, which has USB built in. That lets it connect to a computer as a keyboard, mouse or game controller – just like the Arduino Leonardo.

Unlike the Nano, it doesn’t need a USB-serial converter: Serial is USB, and the hardware UART on D0/D1 stays free as Serial1.

Specifications

ATmega32U4: 8-bit AVR with USB, 16 MHz
32 kB flash (4 kB used by the bootloader), 2.5 kB SRAM, 1 kB EEPROM
20 digital pins plus 4 SPI pins (D14–D17), 7× PWM, 12 analog inputs
UART (Serial1), I2C (D2/D3) and SPI (MISO/SCK/MOSI/SS on the headers and ICSP)
native USB (keyboard, mouse, MIDI, serial)
5 V logic, 7–12 V power input (VIN) or micro USB power
48 × 18 mm

During upload the board briefly disconnects and reconnects as a different device (the bootloader). If uploading fails, press RESET just before uploading – the bootloader then waits 8 seconds for a sketch.

Pinout and pin table

Hover over a pin in the diagram or a table row; use the filter to highlight a bus. You can download the pinout as PNG or SVG.

Pin names:

Download:PNG SVG

License: CC BY 4.0 · How to credit

Pin table – Arduino Micro
Name	Chip port	Direction	UART	I2C	SPI	PWM	ADC	Note
D0	PD2	input/output	RX1					UART RX (Serial1) – hardware UART. Serial in Arduino is USB, not these pins. External interrupt INT2.
D1	PD3	input/output	TX1					UART TX (Serial1); external interrupt INT3
D2	PD1	input/output		SDA				I2C SDA (Wire); external interrupt INT1
D3	PD0	input/output		SCL		PWM		I2C SCL (Wire); PWM (OC0B); external interrupt INT0
D4	PD4	input/output					A6	Analog input A6 (ADC8)
D5	PC6	input/output				PWM		PWM (OC3A)
D6	PD7	input/output				PWM	A7	PWM (OC4D); analog input A7 (ADC10)
D7	PE6	input/output						External interrupt INT6
D8	PB4	input/output					A8	Analog input A8 (ADC11)
D9	PB5	input/output				PWM	A9	PWM (OC1A); analog input A9 (ADC12)
D10	PB6	input/output				PWM	A10	PWM (OC1B); analog input A10 (ADC13)
D11	PB7	input/output				PWM		PWM (OC0A)
D12	PD6	input/output					A11	Analog input A11 (ADC9)
D13	PC7	input/output				PWM		PWM (OC4A); onboard LED "L"
D14	PB3	input/output			MISO			SPI MISO (also on the ICSP header)
D15	PB1	input/output			SCK			SPI SCK (also on the ICSP header)
D16	PB2	input/output			MOSI			SPI MOSI (also on the ICSP header)
D17	PB0	input/output			SS			SPI SS; RX LED – blinks on USB receive
A0	PF7	input/output					ADC7
A1	PF6	input/output					ADC6
A2	PF5	input/output					ADC5
A3	PF4	input/output					ADC4
A4	PF1	input/output					ADC1	Analog input – I2C is on D2/D3, not on A4/A5 as on the Uno
A5	PF0	input/output					ADC0	Analog input – I2C is on D2/D3, not on A4/A5 as on the Uno
3V3		output						3.3 V output from the regulator, for light loads only (max. 50 mA).
AREF		input						ADC reference (default is 5 V)
NC		–
NC		–
5V		input/output						5 V from the regulator or from USB, or 5 V input
RESET		input						Reset – connecting to GND restarts the chip
GND		–
VIN		input						Power input 7–12 V (5 V regulator)
RESET		input						Reset – connecting to GND restarts the chip
GND		–

What to watch out for

I2C is on D2/D3, not on A4/A5 as on the Uno or Nano.
Serial is USB; the hardware UART on D0/D1 is Serial1.
Analog inputs A6–A11 are on digital pins D4, D6, D8, D9, D10 and D12.
A sketch that blocks USB can “lock up” the board – pressing reset right before uploading helps.
The 3V3 pin supplies only 50 mA.