Arduino Zero

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.