Loading source-backed pinouts…
Microcontroller
Arduino Zero
Arduino's SAMD21-based 32-bit UNO-format board with an onboard EDBG debugger and 3.3 V shield headers.
Processor
Microchip SAMD21G18 Arm Cortex-M0+
Logic
3.3 V GPIO
Power
Micro-USB, debug USB, barrel jack, VIN
Format
UNO-style shield layout
Check before wiring
- GPIO is 3.3 V only; 5 V shields can damage the SAMD21.
- A0 is shared with DAC0; treat analog output and input use as mutually exclusive in a design.
- Arduino's pinout PDF lists a low 7 mA maximum per IO pin; budget shield loads accordingly.
- Debug USB, native USB, SWD, and ICSP headers expose different functions.
Interfaces
GPIOI2CSPIUARTADCDACPWMUSBSWD
Source-backed connector
Interactive pin map
Pin map
Connector
Arduino Zero shield headers and debug headers
Signals grouped by function — schematic layout, not to physical scale
Dense header — open Full view for a roomier, fully-labelled diagram.
Simplified diagram, grouped by function — not to physical scale. Pin data is source-backed; verify against the linked documentation.
Hover, tap, or focus a pad to inspect a pin. Use arrow keys to move between pins.
- Official Zero full pinout maps the ATSAMD21G18 to UNO-style headers, ICSP, SWD, and EDBG debug connectors.
- GPIO is 3.3 V logic; this board is not a 5 V UNO electrical clone.
- A0 is also DAC0; D20/D21 are SDA/SCL; ICSP carries the primary SPI header.
- Per Arduino's pinout PDF, maximum current per IO pin is 7 mA.
All 35 pins (table)
| # | Signal | Role | Net | Also / notes |
|---|---|---|---|---|
| Digital | ||||
| 1 | UART | UART | PA11 | |
| 2 | UART | UART | PA10 | |
| 3 | GPIO | PA14 | ||
| 4 | PWM | PA09 | ||
| 5 | PWM | PA08 | ||
| 6 | PWM | PA15 | ||
| 7 | PWM | PA20 | ||
| 8 | GPIO | PA21 | ||
| 9 | PWM | PA06 | ||
| 10 | PWM | PA07 | ||
| 11 | SPI | SPI | PA18 | |
| 12 | SPI | SPI | PA16 / MOSI | |
| 13 | SPI | SPI | PA19 / MISO | |
| 14 | SPI | SPI | PA17 | |
| 21 | I2C | I2C | PA22 | |
| 22 | I2C | I2C | PA23 | |
| Analog / power | ||||
| 14 | DAC | PA02 / ADC0 | ||
| 15 | ADC | PB08 | ||
| 16 | ADC | PB09 | ||
| 17 | ADC | PA04 | ||
| 18 | ADC | PA05 | ||
| 19 | ADC | PB02 | ||
| 22 | Power | AREF | PA03 | |
| 23 | Power | IOREF | ||
| 24 | System | |||
| 25 | Power | 3V3 | ||
| 26 | Power | 5V | ||
| 27 | Ground | GND | ||
| 28 | Power | VIN | ||
| Debug / ICSP | ||||
| 1 | Debug | SWD | ||
| 2 | Debug | SWD | ||
| 3 | SPI | SPI | MISO | |
| 4 | SPI | SPI | MOSI | |
| 5 | SPI | SPI | ||
| 6 | System | |||
Why it matters
- Onboard EDBG provides a full debug interface and virtual COM port.
- Official full pinout PDF documents SAMD21 port aliases, SWD, ICSP, and the DAC pin.
- UNO-style shape is useful for modern 3.3 V shield development.
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