Arduino Micro: specs and pinout
Breadboard-format Arduino built on the ATmega32U4 with native USB, so it can appear to a computer as a keyboard, mouse or virtual serial port.
Specs
| Spec | Value | Source |
|---|---|---|
| Microcontroller | ATmega32u4, 16 MHz | Arduino official documentation Tech Specs: Microcontroller, Clock speed |
| Memory | 32 KB flash, 2.5 KB SRAM, 1 KB EEPROM (the Tech Specs memory line is labelled ATmega328P, which looks like a typo) | Arduino official documentation Tech Specs: Memory |
| I/O voltage | 5 V | Arduino official documentation Tech Specs: Power |
| Input voltage | 7-12 V nominal in Tech Specs; the pinout sheet states VIN 6-9 V input | Arduino official documentation Tech Specs: Power; Arduino datasheet A000053 page 1 |
| DC current per I/O pin | 10 mA in Tech Specs; the pinout sheet marks 40 mA as the maximum current per I/O pin | Arduino official documentation Tech Specs: Power; Arduino datasheet A000053 page 1 |
| Current from 3.3 V pin | 50 mA maximum | Arduino datasheet A000053 Pinout PDF page 1 |
| Pins | 20 digital I/O (7 PWM), 12 analog inputs | Arduino official documentation Tech Specs: Pins |
| Communication | UART, I2C, SPI; native USB (USB 2.0 full-speed device) | Arduino official documentation Tech Specs: Communication; https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7766-8-bit-AVR-ATmega16U4-32U4_Datasheet.pdf Features, p.1 |
| USB connector | Micro USB | Arduino official documentation Tech Specs: USB connector |
| Size | 18 mm x 48 mm | Arduino official documentation Tech Specs: Dimensions |
Power
| Value | Source | |
|---|---|---|
| Supply | 5 V from USB; VIN 7-12 V nominal in Tech Specs, 6-9 V on the pinout sheet | Arduino official documentation Tech Specs: Power; no typical current given |
Pinout
Pin rows are from the official Arduino Micro pinout sheet (A000053), read from the top-view drawing: each row is one header pin, left and right columns listed from the end with the USB connector (top of the drawing) downward. The listing is the official board with headers.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| Left 1 (top to bottom, USB end at top) | D13 (PWM, LED_BUILTIN) | 5 V logic | PC7 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 2 (top to bottom, USB end at top) | +3V3 | 3.3 V | Arduino datasheet A000053 Pinout PDF A000053, page 1 | |
| Left 3 (top to bottom, USB end at top) | AREF | Arduino datasheet A000053 Pinout PDF A000053, page 1 | ||
| Left 4 (top to bottom, USB end at top) | A0 / D18 | 5 V logic | PF7, ADC[7] | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 5 (top to bottom, USB end at top) | A1 / D19 | 5 V logic | PF6, ADC[6] | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 6 (top to bottom, USB end at top) | A2 / D20 | 5 V logic | PF5, ADC[5] | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 7 (top to bottom, USB end at top) | A3 / D21 | 5 V logic | PF4, ADC[4] | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 8 (top to bottom, USB end at top) | A4 / D22 | 5 V logic | PF1, ADC[1] | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 9 (top to bottom, USB end at top) | A5 / D23 | 5 V logic | PF0, ADC[0] | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 10 (top to bottom, USB end at top) | NC | Arduino datasheet A000053 Pinout PDF A000053, page 1 | ||
| Left 11 (top to bottom, USB end at top) | NC | Arduino datasheet A000053 Pinout PDF A000053, page 1 | ||
| Left 12 (top to bottom, USB end at top) | +5V | 5 V | Arduino datasheet A000053 Pinout PDF A000053, page 1 | |
| Left 13 (top to bottom, USB end at top) | RESET | Arduino datasheet A000053 Pinout PDF A000053, page 1 | ||
| Left 14 (top to bottom, USB end at top) | GND | Arduino datasheet A000053 Pinout PDF A000053, page 1 | ||
| Left 15 (top to bottom, USB end at top) | VIN | 6-9 V input per the pinout sheet | Arduino datasheet A000053 Pinout PDF A000053, page 1 | |
| Left 16 (top to bottom, USB end at top) | D14 / CIPO | 5 V logic | PB3 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Left 17 (top to bottom, USB end at top) | D15 / SCK | 5 V logic | PB1 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 1 (top to bottom, USB end at top) | D12 / A11 | 5 V logic | PD6 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 2 (top to bottom, USB end at top) | D11 (PWM) | 5 V logic | PB7 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 3 (top to bottom, USB end at top) | D10 / A10 (PWM) | 5 V logic | PB6 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 4 (top to bottom, USB end at top) | D9 / A9 (PWM) | 5 V logic | PB5 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 5 (top to bottom, USB end at top) | D8 / A8 | 5 V logic | PB4 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 6 (top to bottom, USB end at top) | D7 | 5 V logic | PE6 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 7 (top to bottom, USB end at top) | D6 / A7 (PWM) | 5 V logic | PD7 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 8 (top to bottom, USB end at top) | D5 (PWM) | 5 V logic | PC6 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 9 (top to bottom, USB end at top) | D4 / A6 | 5 V logic | PD4 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 10 (top to bottom, USB end at top) | D3 / SCL (PWM) | 5 V logic | PD0 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 11 (top to bottom, USB end at top) | D2 / SDA | 5 V logic | PD1 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 12 (top to bottom, USB end at top) | GND | Arduino datasheet A000053 Pinout PDF A000053, page 1 | ||
| Right 13 (top to bottom, USB end at top) | RESET | Arduino datasheet A000053 Pinout PDF A000053, page 1 | ||
| Right 14 (top to bottom, USB end at top) | D0 / RX | 5 V logic | PD2 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 15 (top to bottom, USB end at top) | D1 / TX | 5 V logic | PD3 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 16 (top to bottom, USB end at top) | D17 / SS | 5 V logic | PB0 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
| Right 17 (top to bottom, USB end at top) | D16 / COPI | 5 V logic | PB2 | Arduino datasheet A000053 Pinout PDF A000053, page 1 |
Build with it
Project ideas for the Arduino Micro. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Breadboard macro keypad: The 8 keypad lines fit on the Micro's digital pins at 5 V logic and the board sends key presses over USB.
- USB volume knob: Encoder and button use digital pins; the board sends media-key presses over USB.
- Page-turner pedal: Two inputs; the Micro appears as a keyboard and sends page-up and page-down.
Common mistakes
- Feeding VIN above the pinout sheet's 6-9 V input range: the Tech Specs and pinout sheet disagree (7-12 V vs 6-9 V), so stay at 7-9 V or use USB power (source: Arduino datasheet A000053)
- Pulling more than 50 mA from the 3.3 V pin (source: Arduino datasheet A000053)
- Sending constant keystrokes or mouse moves from a sketch: the Arduino page for the sister Leonardo board warns this makes programming difficult; add a start/stop switch (source: Arduino official documentation)
Not covered by the official source
- Arduino publishes no PDF datasheet for this board; the Tech Specs page and the pinout sheet are the sources.
- Tech Specs and pinout sheet disagree on input voltage (7-12 V vs 6-9 V) and per-pin current (10 mA vs 40 mA maximum); both are shown.
- The schematic is not used as a source on this page.
Sources
- Arduino official documentation (Arduino Micro hardware page, Tech Specs)
- Arduino datasheet A000053 (Arduino Micro full pinout, last update 10/11/2020)
- link (Microchip ATmega16U4/ATmega32U4 datasheet, Atmel-7766J 04/2016)