How to Use Adafruit Metro Mini: Examples, Pinouts, and Specs

The Adafruit Metro Mini is a compact, breadboard-friendly microcontroller board based on the ATmega328PB MCU. It is designed to be compatible with the Arduino IDE, allowing users to easily write and upload code to the board. With its small size and extensive I/O capabilities, the Metro Mini is ideal for projects that require a powerful yet space-efficient microcontroller. Common applications include wearable electronics, prototyping, educational purposes, and DIY projects.

• Microcontroller: ATmega328PB
• Operating Voltage: 5V
• Input Voltage (recommended): 6-12V
• Input Voltage (limit): 6-20V
• Digital I/O Pins: 20 (6 of which provide PWM output)
• Analog Input Pins: 6
• DC Current per I/O Pin: 20 mA
• DC Current for 3.3V Pin: 50 mA
• Flash Memory: 32 KB (ATmega328PB) of which 0.5 KB used by bootloader
• SRAM: 2 KB (ATmega328PB)
• EEPROM: 1 KB (ATmega328PB)
• Clock Speed: 16 MHz
• LED_BUILTIN: Pin 13

To use the Adafruit Metro Mini in a circuit:

1. Connect the board to a power source via the VIN pin (6-12V recommended).
2. Connect the GND pin to the common ground of your circuit.
3. Utilize the digital and analog pins as required for your project, ensuring you do not exceed the current ratings.
4. If using PWM, connect to pins 3, 5, 6, 9, 10, or 11.
5. For I2C communication, use pins A4 (SDA) and A5 (SCL).

• Always disconnect the Metro Mini from the power source before making or altering connections.
• Use a current limiting resistor when connecting LEDs to the output pins.
• Avoid applying voltages higher than 5V to any I/O pin.
• Ensure that the total current through all I/O pins does not exceed the limit.

• Metro Mini not recognized by computer: Ensure the drivers are installed and the USB cable is functioning.
• Sketch not uploading: Check the board and port settings in the Arduino IDE, and ensure the correct bootloader is selected.
• I/O pin not working: Verify that the pin is not being overdriven beyond its current limit and that it is configured correctly in your sketch.

• If the Metro Mini is not recognized, try using a different USB cable or port.
• When uploading sketches, ensure no other programs are using the same COM port.
• Use external power supplies for components that draw more current than the Metro Mini can provide.

Here is a simple example of blinking the onboard LED using the Arduino IDE:

// Pin 13 has an LED connected on most Arduino boards.
int led = 13;

// The setup routine runs once when you press reset:
void setup() {
  // Initialize the digital pin as an output.
  pinMode(led, OUTPUT);
}

// The loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);   // Turn the LED on (HIGH is the voltage level)
  delay(1000);               // Wait for a second
  digitalWrite(led, LOW);    // Turn the LED off by making the voltage LOW
  delay(1000);               // Wait for a second
}

Remember to select "Adafruit Metro Mini" as the board in the Arduino IDE before uploading the code. If the Metro Mini is not listed, you may need to install the Adafruit board definitions via the Boards Manager.

For more advanced usage and additional examples, refer to the Adafruit Metro Mini guide and the Arduino language reference.