Adafruit Metro M4 feat. Microchip ATSAMD51

Name: Adafruit Metro M4 feat. Microchip ATSAMD51
Brand: Adafruit
SKU: 3382

Arduino-compatible Metro board with ATSAMD51 Cortex-M4 at 120 MHz, 512 KB flash, 192 KB RAM, 2 MB QSPI flash, and 6 hardware SERCOM ports (I2C, SPI, UART), plus stereo I2S and native USB. Runs CircuitPython or Arduino IDE. Logic and power at 3.3 V; not 5 V tolerant on I/O.

Logical pinout · physical placement not verified

3 grouped source records are expanded into separate logical pads where unambiguous; physical placement is not implied.

Micro USB
Micro USB port powers the Metro M4 with 5V at about 500mA and provides the USB data/programming connection; Adafruit notes the USB input has a fuse that trips temporarily above about 1000mA.
Type · USBVoltage · 5V USB input; draw up to about 500mA combined between Vin, 5V and 3.3V supplies when USB-powered.
DC jack
5.5mm/2.1mm centre-positive DC jack for external board power; Adafruit states this is one of the two primary power inputs.
Type · PowerVoltage · 6V-12V input recommended on the DC jack; up to about 800mA between 5V and 3.3V supplies, and 2A from Vin, per Adafruit.
3V
Output from the onboard 3.3V regulator for peripherals and logic reference.
Type · PowerVoltage · 3.3V output, 500mA peak per Adafruit; board logic is 3.3V.
5V
Output from the 5V regulator when DC jack powered, or from USB when USB powered.
Type · PowerVoltage · 5V output, about 500mA peak from USB or about 800mA peak from DC jack per Adafruit.
GND
Common ground for all power and logic connections.
Type · GroundVoltage · 0V reference.
Vin
Higher of the DC jack or USB voltage; can be used as the raw input/output rail described by Adafruit.
Type · PowerVoltage · Vin is the DC jack voltage when DC is connected, e.g. 9V, or 5V when only USB is connected.
#0RX
GPIO #0 and Serial1 hardware UART receive input.
Type · UARTVoltage · 3.3V logic.
#1TX
GPIO #1 and Serial1 hardware UART transmit output; also used as I2S SDI on this board according to Adafruit's I2S mapping.
Type · UARTVoltage · 3.3V logic.
#2-#12
General-purpose digital GPIO pins; Adafruit notes all pins except SCL can do PWM output, with pins also usable as interrupt inputs.
Type · GPIOVoltage · 3.3V logic.
#13L
GPIO #13, PWM-capable, connected to the red LED marked L next to the USB jack.
Type · GPIOVoltage · 3.3V logic.
SDAA6
I2C Wire data pin; also available as analogue input A6. Adafruit notes no pull-up is fitted by default.
Type · Analog, I2CVoltage · 3.3V logic; external I2C pull-up of about 2.2K-10K may be needed.
SCLA7
I2C Wire clock pin; also available as analogue input A7. Adafruit notes no pull-up is fitted by default.
Type · Analog, I2CVoltage · 3.3V logic; external I2C pull-up of about 2.2K-10K may be needed.
A0
Analogue input A0 and true analogue output DAC channel; also digital I/O.
Type · AnalogVoltage · 0V to 3.3V analogue output range per Adafruit.
A1
Analogue input A1 and true analogue output DAC channel; also digital I/O.
Type · AnalogVoltage · 0V to 3.3V analogue output range per Adafruit.
A2-A5
Analogue input pins that are also usable as digital I/O pins.
Type · AnalogVoltage · 3.3V logic / analogue input range scoped by board logic.
SCKMOSIMISO
Hardware SPI pins connected to the 2x3 header; Adafruit says they can also be used as everyday GPIO but are best kept free for high-speed hardware SPI.
Type · SPIVoltage · 3.3V logic.
I2S pins
Fixed I2S peripheral mapping: pin 8 SDO/data out, pin 1 SDI/data in, pin 3 bit clock, pin 9 word select, and pin 2 master clock.
Type · GPIOVoltage · 3.3V logic.
SWD header
2x5 0.05 inch pitch SWD debug/programming interface exposed on the board.
Type · UnknownVoltage · 3.3V debug interface implied by ATSAMD51 board logic.

Pin	Type	Function	Voltage
Micro USB	USB	Micro USB port powers the Metro M4 with 5V at about 500mA and provides the USB data/programming connection; Adafruit notes the USB input has a fuse that trips temporarily above about 1000mA.	5V USB input; draw up to about 500mA combined between Vin, 5V and 3.3V supplies when USB-powered.
DC jack	Power	5.5mm/2.1mm centre-positive DC jack for external board power; Adafruit states this is one of the two primary power inputs.	6V-12V input recommended on the DC jack; up to about 800mA between 5V and 3.3V supplies, and 2A from Vin, per Adafruit.
3V	Power	Output from the onboard 3.3V regulator for peripherals and logic reference.	3.3V output, 500mA peak per Adafruit; board logic is 3.3V.
5V	Power	Output from the 5V regulator when DC jack powered, or from USB when USB powered.	5V output, about 500mA peak from USB or about 800mA peak from DC jack per Adafruit.
GND	Ground	Common ground for all power and logic connections.	0V reference.
Vin	Power	Higher of the DC jack or USB voltage; can be used as the raw input/output rail described by Adafruit.	Vin is the DC jack voltage when DC is connected, e.g. 9V, or 5V when only USB is connected.
#0RX	UART	GPIO #0 and Serial1 hardware UART receive input.	3.3V logic.
#1TX	UART	GPIO #1 and Serial1 hardware UART transmit output; also used as I2S SDI on this board according to Adafruit's I2S mapping.	3.3V logic.
#2-#12	GPIO	General-purpose digital GPIO pins; Adafruit notes all pins except SCL can do PWM output, with pins also usable as interrupt inputs.	3.3V logic.
#13L	GPIO	GPIO #13, PWM-capable, connected to the red LED marked L next to the USB jack.	3.3V logic.
SDAA6	Analog, I2C	I2C Wire data pin; also available as analogue input A6. Adafruit notes no pull-up is fitted by default.	3.3V logic; external I2C pull-up of about 2.2K-10K may be needed.
SCLA7	Analog, I2C	I2C Wire clock pin; also available as analogue input A7. Adafruit notes no pull-up is fitted by default.	3.3V logic; external I2C pull-up of about 2.2K-10K may be needed.
A0	Analog	Analogue input A0 and true analogue output DAC channel; also digital I/O.	0V to 3.3V analogue output range per Adafruit.
A1	Analog	Analogue input A1 and true analogue output DAC channel; also digital I/O.	0V to 3.3V analogue output range per Adafruit.
A2-A5	Analog	Analogue input pins that are also usable as digital I/O pins.	3.3V logic / analogue input range scoped by board logic.
SCKMOSIMISO	SPI	Hardware SPI pins connected to the 2x3 header; Adafruit says they can also be used as everyday GPIO but are best kept free for high-speed hardware SPI.	3.3V logic.
I2S pins	GPIO	Fixed I2S peripheral mapping: pin 8 SDO/data out, pin 1 SDI/data in, pin 3 bit clock, pin 9 word select, and pin 2 master clock.	3.3V logic.
SWD header	Unknown	2x5 0.05 inch pitch SWD debug/programming interface exposed on the board.	3.3V debug interface implied by ATSAMD51 board logic.

Logical pinout · physical placement not verified

3 grouped source records are expanded into separate logical pads where unambiguous; physical placement is not implied.

Pin details

18 connections

Micro USB
Micro USB port powers the Metro M4 with 5V at about 500mA and provides the USB data/programming connection; Adafruit notes the USB input has a fuse that trips temporarily above about 1000mA.
USBVoltage · 5V USB input; draw up to about 500mA combined between Vin, 5V and 3.3V supplies when USB-powered.
DC jack
5.5mm/2.1mm centre-positive DC jack for external board power; Adafruit states this is one of the two primary power inputs.
PowerVoltage · 6V-12V input recommended on the DC jack; up to about 800mA between 5V and 3.3V supplies, and 2A from Vin, per Adafruit.
3V
Output from the onboard 3.3V regulator for peripherals and logic reference.
PowerVoltage · 3.3V output, 500mA peak per Adafruit; board logic is 3.3V.
5V
Output from the 5V regulator when DC jack powered, or from USB when USB powered.
PowerVoltage · 5V output, about 500mA peak from USB or about 800mA peak from DC jack per Adafruit.
GND
Common ground for all power and logic connections.
GroundVoltage · 0V reference.
Vin
Higher of the DC jack or USB voltage; can be used as the raw input/output rail described by Adafruit.
PowerVoltage · Vin is the DC jack voltage when DC is connected, e.g. 9V, or 5V when only USB is connected.
#0RX
GPIO #0 and Serial1 hardware UART receive input.
UARTVoltage · 3.3V logic.
#1TX
GPIO #1 and Serial1 hardware UART transmit output; also used as I2S SDI on this board according to Adafruit's I2S mapping.
UARTVoltage · 3.3V logic.
#2-#12
General-purpose digital GPIO pins; Adafruit notes all pins except SCL can do PWM output, with pins also usable as interrupt inputs.
GPIOVoltage · 3.3V logic.
#13L
GPIO #13, PWM-capable, connected to the red LED marked L next to the USB jack.
GPIOVoltage · 3.3V logic.
SDAA6
I2C Wire data pin; also available as analogue input A6. Adafruit notes no pull-up is fitted by default.
Analog, I2CVoltage · 3.3V logic; external I2C pull-up of about 2.2K-10K may be needed.
SCLA7
I2C Wire clock pin; also available as analogue input A7. Adafruit notes no pull-up is fitted by default.
Analog, I2CVoltage · 3.3V logic; external I2C pull-up of about 2.2K-10K may be needed.
A0
Analogue input A0 and true analogue output DAC channel; also digital I/O.
AnalogVoltage · 0V to 3.3V analogue output range per Adafruit.
A1
Analogue input A1 and true analogue output DAC channel; also digital I/O.
AnalogVoltage · 0V to 3.3V analogue output range per Adafruit.
A2-A5
Analogue input pins that are also usable as digital I/O pins.
AnalogVoltage · 3.3V logic / analogue input range scoped by board logic.
SCKMOSIMISO
Hardware SPI pins connected to the 2x3 header; Adafruit says they can also be used as everyday GPIO but are best kept free for high-speed hardware SPI.
SPIVoltage · 3.3V logic.
I2S pins
Fixed I2S peripheral mapping: pin 8 SDO/data out, pin 1 SDI/data in, pin 3 bit clock, pin 9 word select, and pin 2 master clock.
GPIOVoltage · 3.3V logic.
SWD header
2x5 0.05 inch pitch SWD debug/programming interface exposed on the board.
UnknownVoltage · 3.3V debug interface implied by ATSAMD51 board logic.

Start wiring

USB · 3.3 V

Confirm the data interface matches your host board.

Module pins: 5V, Vin, GND. Schematik maps them to your board in the app.

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