How to Use Adafruit Feather 328P: Examples, Pinouts, and Specs

The Adafruit Feather 328P is a versatile and compact development board that harnesses the power of the ATmega328P microcontroller, the same MCU found in the popular Arduino Uno. This board is part of the Feather ecosystem, a series of development boards by Adafruit that are thin, light, and feature a built-in USB and battery charging. The Feather 328P is particularly well-suited for portable projects, wearables, and low-power applications that require a balance between performance and energy efficiency.

• Wearable electronics
• Portable instruments
• IoT devices
• Battery-powered projects
• Prototyping and educational purposes

• Microcontroller: ATmega328P
• Operating Voltage: 3.3V
• Input Voltage: 3.7-6V via battery and up to 12V via the USB pin
• Digital I/O Pins: 20
• PWM Channels: 6
• Analog Input Channels: 6
• DC Current per I/O Pin: 20 mA
• Clock Speed: 8 MHz
• Flash Memory: 32 KB (ATmega328P) of which 0.5 KB used by bootloader
• SRAM: 2 KB (ATmega328P)
• EEPROM: 1 KB (ATmega328P)

1. Powering the Board:

   • You can power the Adafruit Feather 328P via the USB connection, a LiPo battery, or through the BAT pin.
   • Ensure that the power source does not exceed the recommended voltage levels.

2. Programming the Board:

   • Connect the board to your computer using a micro-USB cable.
   • Select "Arduino Pro or Pro Mini" from the Boards menu in the Arduino IDE, and choose "ATmega328P (3.3V, 8 MHz)" as the processor.

3. Connecting Peripherals:

   • Use the digital and analog pins to connect sensors, actuators, and other peripherals.
   • Respect the maximum current rating of 20 mA per I/O pin to prevent damage.

• Always disconnect the battery or power source before making or altering connections.
• Use a current limiting resistor with LEDs and other sensitive components.
• Avoid exposing the board to static electricity or moisture.
• When using I2C or SPI, ensure that the connected devices are compatible with the board's operating voltage.

• Board not recognized by computer:

  • Check the USB cable and port.
  • Ensure that the correct drivers are installed.

• Incorrect voltage readings:

  • Verify that the AREF pin is configured correctly if used.
  • Check for proper grounding in the circuit.

• Program not running as expected:

  • Double-check the code for errors.
  • Ensure that the board is correctly selected in the Arduino IDE.

• If the board is not recognized, try a different USB cable or port, and reset the board.
• For voltage issues, use a multimeter to check the power supply and the voltage at the pins.
• Review the connections and solder joints for any loose or cold solder points.

Q: Can I use the Arduino Uno code with the Feather 328P? A: Yes, most code written for the Arduino Uno will work with the Feather 328P, as they share the same microcontroller.

Q: How do I charge the connected LiPo battery? A: The Feather 328P has a built-in charging circuit. Simply connect the battery and power the board via USB.

Q: What is the maximum battery voltage that can be connected to the BAT pin? A: The maximum battery voltage should not exceed 6V.

Q: Can I use the Feather 328P with 5V components? A: The Feather 328P operates at 3.3V. Use level shifters or check if the 5V components are 3.3V compatible before connecting them directly.

// Blink example for Adafruit Feather 328P

void setup() {
  pinMode(LED_BUILTIN, OUTPUT); // Initialize the LED pin as an output
}

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

Remember to select the correct board and processor before uploading the code to the Adafruit Feather 328P. This example will blink the onboard LED and is a simple test to verify that your setup is working correctly.