# Arduino Zero > 32-bit ARM Cortex-M0+ Arduino in UNO form factor with ATSAMD21G18 at 48 MHz, 256KB flash, 32KB SRAM, onboard EDBG debugger, dual USB ports, 12-bit ADC/DAC — designed for IoT, wearables, and robotics. ## Quick Facts - **Brand:** Arduino - **Board Type:** dev-board - **Price:** ~$54.95 - **Product Readiness:** developer - **CPU:** ATSAMD21G18 ARM Cortex-M0+ @ 48 MHz - **CPU Architecture:** ARM Cortex-M0+ - **CPU Cores:** 1 - **RAM:** 32 KB - **Flash:** 256 KB - **Power:** 5V via Micro USB (Programming or Native port) or 7-12V DC barrel jack - **Operating Voltage:** 3.3V - **Dimensions:** 70.3 × 53.5 × 12.7 mm - **Weight:** 22.6g ## Open Source - **Firmware:** Yes - **Schematics:** Yes - **PCB Layout:** Yes ## Compatible Firmware arduino, circuitpython, platformio, micropython ## Use Cases - iot - robotics - wearable - education - prototyping - automation ## Components - **ATSAMD21G18** (mcu): Microchip ARM Cortex-M0+ at 48 MHz, 256KB flash, 32KB SRAM, native USB, 12-bit ADC, 10-bit DAC, hardware EDBG debugger — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FSAM_D21_DA1_Family_DataSheet_DS40001882H.pdf&ref=openhardware.directory&product=arduino-zero&source=md-export) ## Protocols - **UART**: TX: D1, RX: D0, TX1: D1, RX1: D0 - **SPI**: MOSI: D23, MISO: D22, SCK: D24, SS: D10 - **I2C**: SDA: D20, SCL: D21 - **USB** - **SWD/JTAG** ## GPIO Map | Pin | Name | Type | Functions | |-----|------|------|-----------| | D0 | UART RX (Serial1) | UART | digital-input, digital-output | | D1 | UART TX (Serial1) | UART | digital-input, digital-output | | D2 | Digital I/O (no PWM) | — | digital-input, digital-output | | D3 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D4 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D5 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D6 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D7 | Digital I/O (no PWM) | — | digital-input, digital-output | | D8 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D9 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D10 | SPI SS, PWM | SPI | digital-input, digital-output, pwm | | D11 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D12 | Digital I/O, PWM | — | digital-input, digital-output, pwm | | D13 | Onboard LED, PWM | — | digital-input, digital-output, pwm | | D20 | I2C SDA — SAMD21 PA22 | I2C | digital-input, digital-output | | D21 | I2C SCL — SAMD21 PA23 | I2C | digital-input, digital-output | | D22 | SPI MISO — SAMD21 PA14 | SPI | digital-input, digital-output | | D23 | SPI MOSI — SAMD21 PA12 | SPI | digital-input, digital-output | | D24 | SPI SCK — SAMD21 PA13 | SPI | digital-input, digital-output | | A0 | 10-bit DAC Output, 12-bit Analog Input | — | analog-input, analog-output, digital-input, digital-output | | A1 | 12-bit Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A2 | 12-bit Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A3 | 12-bit Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A4 | 12-bit Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | | A5 | 12-bit Analog Input / Digital I/O | — | analog-input, digital-input, digital-output | ## Available Software - **[Arduino IDE]()** (open-source) - **[PlatformIO]()** (open-source) - **[MicroPython]()** (open-source) ## Description ## Overview The Arduino Zero is a 32-bit Arduino board in the classic UNO/Leonardo form factor, built around the Atmel ATSAMD21G18 ARM Cortex-M0+ processor at 48 MHz. It marks Arduino's transition to 32-bit ARM architecture for the standard UNO pin layout, offering 256KB of flash and 32KB of SRAM — dramatically more than the 8-bit UNO — while maintaining shield compatibility. A distinguishing feature of the Zero is its integrated Embedded Debugger (EDBG) provided by a second Atmel microcontroller. This enables full in-circuit debugging via the Arduino IDE without any additional hardware programmer, including breakpoints, memory inspection, and single-step execution — capabilities previously requiring external JTAG/SWD adapters. The board includes two Micro USB ports: the Programming port (via EDBG, for normal sketch uploading and serial monitoring) and the Native port (direct ARM USB, for USB device emulation). The 12-bit ADC provides higher resolution analog measurements than 8-bit AVR boards, and a single 10-bit DAC output enables analog signal generation. All GPIO pins support PWM except pins 2 and 7. Operating at 3.3V with 7mA maximum per I/O pin (versus 40mA on 5V AVR boards), the Zero requires careful design when interfacing with legacy 5V sensors or shields. The standard UNO form factor ensures broad shield compatibility, though 5V shields may require level shifting. ## Where to Buy - [Adafruit](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F2843&ref=openhardware.directory&product=arduino-zero&source=md-export) — 54.95 ## Resources - [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F2843&ref=openhardware.directory&product=arduino-zero&source=md-export) - [wiki](https://openhardware.directory/r?to=https%3A%2F%2Fdocs.arduino.cc%2Fhardware%2Fzero&ref=openhardware.directory&product=arduino-zero&source=md-export) - [datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FSAM_D21_DA1_Family_DataSheet_DS40001882H.pdf&ref=openhardware.directory&product=arduino-zero&source=md-export) ## Tags `arduino`, `atsamd21`, `arm`, `cortex-m0`, `32-bit`, `debugger`, `edbg`, `iot` ## Images ![Arduino Zero](https://nbg1.your-objectstorage.com/openhardware-directory/entities/arduino-zero/fdfe7f038dcd.jpg) ![Arduino Zero](https://nbg1.your-objectstorage.com/openhardware-directory/entities/arduino-zero/90276ce6bacb.jpg) --- [View full device page](https://openhardware.directory/devices/arduino-zero)