Adafruit Metro M4 Express AirLift (WiFi) - Lite
Metro M4 development board with Microchip ATSAMD51 at 120 MHz and an on-board ESP32 WiFi co-processor with pre-loaded TLS root certificates.
Metro M4 development board with Microchip ATSAMD51 at 120 MHz and an on-board ESP32 WiFi co-processor with pre-loaded TLS root certificates.
Micro USB power/data connection; Adafruit states it is one primary way to power the Metro M4 Express AirLift.
5.5mm/2.1mm centre-positive DC input jack; Adafruit states it is the other primary power input.
Board VIN supply rail available on the Metro header, tied to external input power path per pinouts guide power section.
5V board supply rail exposed on the Metro header.
Regulated 3.3V board supply rail exposed on the Metro header.
Ground pins on the Metro headers.
GPIO #0, receive input for Serial1 hardware UART, per Adafruit pinouts guide.
GPIO #1, transmit output for Serial1 hardware UART, per Adafruit pinouts guide.
General-purpose digital GPIO pins; guide states all logic pins are 3.3V and interrupt-capable.
GPIO #13, connected to the red LED marked L next to the USB jack.
I2C/Wire data pin on the Metro header.
I2C/Wire clock pin on the Metro header; guide notes SCL is the exception to PWM availability.
Analogue-capable header pins; A0 has true analogue output per Adafruit pinouts guide.
SPI bus exposed for board peripherals and header use; ESP32 AirLift uses SPI data plus dedicated control pins.
ESP32 AirLift chip-select pin for WiFi SPI interface, named by Adafruit guide.
ESP32 AirLift ready/busy acknowledgement pin, named by Adafruit guide.
ESP32 AirLift reset pin, named by Adafruit guide.
Dedicated UART between the main MCU and ESP32 AirLift; guide states it is separate from the Metro RX/TX breakout pins.
ESP32 RTS pin exposed for advanced serial contexts, per Adafruit guide.
ESP32 GPIO0 bootloader-enable pin, per Adafruit guide.
| Pin | Position | Type | Function | Voltage |
|---|---|---|---|---|
| USB | power | Micro USB power/data connection; Adafruit states it is one primary way to power the Metro M4 Express AirLift. | USB 5V input, fused; guide states up to about 500mA across Vin/5V/3.3V supplies combined | |
| DC jack | power | 5.5mm/2.1mm centre-positive DC input jack; Adafruit states it is the other primary power input. | 6V-12V input stated by Adafruit guide | |
| VIN | power | Board VIN supply rail available on the Metro header, tied to external input power path per pinouts guide power section. | ||
| 5V | power | 5V board supply rail exposed on the Metro header. | 5V | |
| 3.3V | power | Regulated 3.3V board supply rail exposed on the Metro header. | 3.3V | |
| GND | ground | Ground pins on the Metro headers. | ||
| #0 / RX | signal | GPIO #0, receive input for Serial1 hardware UART, per Adafruit pinouts guide. | 3.3V logic | |
| #1 / TX | signal | GPIO #1, transmit output for Serial1 hardware UART, per Adafruit pinouts guide. | 3.3V logic | |
| #2-#12 | signal | General-purpose digital GPIO pins; guide states all logic pins are 3.3V and interrupt-capable. | 3.3V logic | |
| #13 / L | signal | GPIO #13, connected to the red LED marked L next to the USB jack. | 3.3V logic | |
| SDA | signal | I2C/Wire data pin on the Metro header. | 3.3V logic | |
| SCL | signal | I2C/Wire clock pin on the Metro header; guide notes SCL is the exception to PWM availability. | 3.3V logic | |
| A0-A5 | signal | Analogue-capable header pins; A0 has true analogue output per Adafruit pinouts guide. | 3.3V logic/analogue domain | |
| SPI | signal | SPI bus exposed for board peripherals and header use; ESP32 AirLift uses SPI data plus dedicated control pins. | 3.3V logic | |
| ESP_CS / SPIWIFI_SS / 36 | signal | ESP32 AirLift chip-select pin for WiFi SPI interface, named by Adafruit guide. | 3.3V logic | |
| ESP_BUSY / SPIWIFI_ACK / 37 | signal | ESP32 AirLift ready/busy acknowledgement pin, named by Adafruit guide. | 3.3V logic | |
| ESP_RESET / SPIWIFI_RESET / 38 | signal | ESP32 AirLift reset pin, named by Adafruit guide. | 3.3V logic | |
| ESP_RX / ESP_TX | signal | Dedicated UART between the main MCU and ESP32 AirLift; guide states it is separate from the Metro RX/TX breakout pins. | 3.3V logic | |
| ESP_RTS / 34 | signal | ESP32 RTS pin exposed for advanced serial contexts, per Adafruit guide. | 3.3V logic | |
| ESP_GPIO0 / 35 | signal | ESP32 GPIO0 bootloader-enable pin, per Adafruit guide. | 3.3V logic |
USB · 3.3 V
Confirm the data interface matches your host board.
Module pins: USB, DC jack, VIN, 5V, 3.3V, GND, #0 / RX, #1 / TX. Schematik maps them to your board in the app.
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