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Microcontroller
SparkFun Pro Micro
The ATmega32U4 board behind countless macro pads and keyboards.
- GPIO
- I2C
- SPI
- UART
- ADC
- PWM
- USB
- Processor
- ATmega32U4
- Logic
- 5 V at 16 MHz, or 3.3 V at 8 MHzTreat as not 5 V tolerant
- Power
- Micro-USB or USB-C, RAW pin
- Format
- Pro Micro 12+12 headers
Before you wire
2 cautions- Two voltage versions exist; check yours before wiring.
- SPI has no hardware CS on the header: pick any free pin.
Pin map
Connector
Pro Micro 12+12 headers
USB at top, component side up, headers on both long edges
Simplified technical illustration. Pin data is source-backed; verify against the linked documentation before wiring.
Pin
Hover, tap, or arrow to a pad to inspect it.
- Arduino pin numbers follow SparkFun's promicro core variant; the layout matches the ATmega32U4 Pro Micro footprint.
- D15 (SCK), D14 (MISO), and D16 (MOSI) are the SPI pins; RX and TX LEDs use pins that are not broken out.
- Logic level follows the board: 5 V at 16 MHz, or 3.3 V at 8 MHz. Check which one you own.
All 24 pins (table)
| # | Signal | Role | Net | Also / notes |
|---|---|---|---|---|
| 1 | UART | UART | PD3 / TXD1 | |
| 2 | UART | UART | PD2 / RXD1 | |
| 3 | Ground | GND | ||
| 4 | Ground | GND | ||
| 5 | I2C | I2C | PD1 | |
| 6 | I2C | I2C | PD0 | |
| 7 | ADC | PD4 | ||
| 8 | PWM | PC6 | ||
| 9 | ADC | PD7 | ||
| 10 | GPIO | PE6 | ||
| 11 | ADC | PB4 | ||
| 12 | ADC | PB5 | ||
| 13 | Power | RAW | ||
| 14 | Ground | GND | ||
| 15 | System | |||
| 16 | Power | VCC | ||
| 17 | ADC | PF4 | ||
| 18 | ADC | PF5 | ||
| 19 | ADC | PF6 | ||
| 20 | ADC | PF7 | ||
| 21 | SPI | SPI | PB1 | |
| 22 | SPI | SPI | PB3 | |
| 23 | SPI | SPI | PB2 | |
| 24 | ADC | PB6 |
Revision notes
- Arduino pin numbers follow SparkFun's promicro core variant; the layout matches the ATmega32U4 Pro Micro footprint.
Source references
Why it matters
- Native USB HID from the ATmega32U4.
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