Adafruit Metro M4 Express AirLift

Overview

The Adafruit Metro M4 Express AirLift combines the high-performance ATSAMD51J19 ARM Cortex M4F processor with an ESP32 AirLift WiFi co-processor in the standard Arduino Uno form factor. This pairing delivers both the computing power for complex CircuitPython or Arduino applications and WiFi connectivity with full TLS/SSL support, AES-256 encryption, and a true random number generator — all without requiring any WiFi library changes on the main SAMD51 processor.

The ATSAMD51J19 at 120 MHz provides 512 KB of internal flash, 192 KB of SRAM, 2 MB of QSPI flash, 25 GPIO pins with 8 analog inputs, 22 PWM outputs, dual 1 MSPS 12-bit DAC and ADC, 6 SERCOM interfaces, stereo I2S, and 8-bit parallel capture. Native USB handles HID, MIDI, and CDC modes. The Arduino-compatible form factor accepts thousands of existing shields.

The AirLift ESP32 co-processor handles all WiFi protocol stack operations, offloading network processing from the main M4 processor and keeping the WiFi implementation isolated from the main application code. Data is transferred between the SAMD51 and ESP32 via SPI, and Adafruit's WiFiNINA library provides a familiar interface. The AirLift handles WPA2 Enterprise and modern TLS cipher suites, making it suitable for secure cloud IoT applications.

Power input accepts 7-9V DC via barrel jack or 5V USB Micro, with a 3.3V regulated output. The board is ideal for IoT dashboards, secure data logging, connected displays, and retrofit projects requiring high performance plus WiFi in a familiar Arduino hardware ecosystem.