How to Use Adafruit Metro M4 Express: Examples, Pinouts, and Specs

The Adafruit Metro M4 Express is a feature-rich development board designed for makers and hobbyists who require a robust platform for building electronic projects. Based on the Microchip ATSAMD51 microcontroller, this board is compatible with a vast array of sensors and actuators, making it ideal for applications ranging from simple LED blinkers to complex robotics.

• Prototyping IoT devices
• Educational purposes for learning electronics and programming
• DIY home automation systems
• Wearable electronics
• Custom controllers for robotics
• Data logging and sensor monitoring

The Adafruit Metro M4 Express is equipped with a multitude of technical features that provide flexibility and power for various projects.

• Microcontroller: ATSAMD51J19
• Clock Speed: 120 MHz
• Flash Memory: 512 KB
• RAM: 192 KB
• Digital I/O Pins: 25
• PWM Channels: 12
• Analog Input Pins: 6 (12-bit ADC)
• Analog Output Pins: 1 (10-bit DAC)
• Operating Voltage: 3.3V
• Input Voltage (recommended): 7-9V
• Input Voltage (limits): 6-12V
• Interfaces: I2C, SPI, UART
• USB Connectivity: Native USB support

1. Powering the Board: Connect a 7-9V power supply to the VIN and GND pins, or power the board via the USB connection.
2. Connecting I/O Devices: Attach sensors, actuators, or other peripherals to the digital and analog pins as required by your project.
3. Programming the Board: Use the Arduino IDE or other compatible software to write and upload code to the Metro M4 Express.

• Always ensure that the power supply voltage is within the specified limits to prevent damage.
• When connecting external components, make sure they are compatible with the board's operating voltage (3.3V logic level).
• Avoid drawing more than 20 mA from any I/O pin.
• Use external power sources when driving high-current devices like motors or high-power LEDs.

// Blink an LED connected to pin 13

void setup() {
  pinMode(13, OUTPUT); // Set pin 13 as an output
}

void loop() {
  digitalWrite(13, HIGH);   // Turn the LED on
  delay(1000);              // Wait for a second
  digitalWrite(13, LOW);    // Turn the LED off
  delay(1000);              // Wait for a second
}

• Board not recognized by computer: Ensure the USB cable is properly connected and the board is powered on. Try a different USB port or cable if necessary.
• Sketch not uploading: Check for correct board and port selection in the Arduino IDE. Ensure the bootloader is not corrupted.
• I/O pin not functioning: Verify that the pin is not being used by another peripheral and is configured correctly in your code.

• If the board is not recognized, press the reset button twice quickly to enter bootloader mode.
• For I/O issues, use a multimeter to check for continuity and correct voltage levels.
• Consult the Adafruit forums and online resources for community support and additional troubleshooting advice.

Q: Can I power the Metro M4 Express with a battery? A: Yes, you can use a battery within the input voltage limits (6-12V).

Q: Is the Metro M4 Express compatible with all Arduino shields? A: While many shields will work, some may not be compatible due to differences in voltage levels or pin assignments. Always check shield specifications.

Q: How do I use the onboard DAC? A: The DAC can be used to output analog voltages. Use the analogWrite() function in your code to control the DAC pin.

For further assistance, Adafruit provides extensive documentation and a supportive community forum to help you with your Metro M4 Express projects.