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Microcontroller
Arduino MKR Zero
SAMD21 MKR board with microSD, aimed at compact audio, logging, and battery projects.
- GPIO
- I2C
- SPI
- UART
- ADC
- DAC
- PWM
- USB
- Processor
- Microchip SAMD21G18
- Logic
- 3.3 V GPIONot 5 V tolerant
- Power
- Micro-USB, Li-Po connector, VIN
- Format
- MKR module
Before you wire
3 cautions- MKR boards use 3.3 V IO, not 5 V Arduino UNO logic.
- SPI pins are shared with microSD use.
- Battery charging and VIN limits differ from bare Li-Po breakout assumptions.
Pin map
Connector
Arduino MKR dual 14-pin 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.
- Standard Arduino MKR form factor; SAMD21G18 ports from the official Arduino pinout PDF.
- GPIO is 3.3 V only and is not 5 V tolerant; max 7 mA per pin.
- A0 (PA02) is a true DAC output. SPI uses an onboard SD card; CIPO/COPI were formerly MISO/MOSI.
- Left header positions 1-14, right header positions 15-28.
All 28 pins (table)
| # | Signal | Role | Net | Also / notes |
|---|---|---|---|---|
| 1 | Alt | PA03 · analog reference | ||
| 2 | DAC | PA02 · true DAC output | ||
| 3 | ADC | PB02 | ||
| 4 | ADC | PB03 | ||
| 5 | ADC | PA04 | ||
| 6 | ADC | PA05 | ||
| 7 | ADC | PA06 | ||
| 8 | ADC | PA07 | ||
| 9 | PWM | PA22 | ||
| 10 | PWM | PA23 | ||
| 11 | PWM | PA10 | ||
| 12 | PWM | PA11 | ||
| 13 | PWM | PB10 | ||
| 14 | PWM | PB11 | ||
| 15 | Power | 5V | ||
| 16 | Power | VIN | input voltage to the board | |
| 17 | Power | 3V3 | ||
| 18 | Ground | GND | ||
| 19 | System | |||
| 20 | UART | UART | PB22 | |
| 21 | UART | UART | PB23 | |
| 22 | I2C | I2C | PA09 | |
| 23 | I2C | I2C | PA08 | |
| 24 | SPI | SPI | PA19 · MISO | |
| 25 | SPI | SPI | PA17 | |
| 26 | SPI | SPI | PA16 · MOSI | |
| 27 | PWM | PA21 | ||
| 28 | PWM | PA20 |
Source references
Why it matters
- Official docs provide pinout and board resources.
- Integrated microSD socket makes data logging easy.
- MKR ecosystem shields fit the compact header layout.
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