How to Use Adafruit Feather 32u4 Adalogger: Examples, Pinouts, and Specs

The Adafruit Feather 32u4 Adalogger is a versatile and portable development board that combines the power of the ATmega32u4 microcontroller with the convenience of an onboard microSD card slot for data logging. This board is part of the Feather ecosystem, designed by Adafruit for ease of use and flexibility. It is ideal for projects that require data collection, such as environmental monitoring, experimental data logging, or even as a tiny, stand-alone GPS logger.

• Environmental data logging (temperature, humidity, pressure)
• GPS tracking and logging
• Wearable devices
• Educational projects and prototyping
• IoT and smart home devices

• Microcontroller: ATmega32u4
• Operating Voltage: 3.3V
• Input Voltage: 3.7-6V via battery and up to 12V via the USB or VIN pin
• Clock Speed: 8 MHz
• Digital I/O Pins: 20
• PWM Channels: 7
• Analog Input Channels: 12
• DC Current per I/O Pin: 40 mA
• Flash Memory: 32 KB (ATmega32u4) of which 4 KB used by bootloader
• SRAM: 2.5 KB (ATmega32u4)
• EEPROM: 1 KB (ATmega32u4)
• MicroSD card slot for data logging

1. Powering the Adalogger: You can power the Adalogger through the USB connection, a LiPo battery, or an external power supply connected to the VIN pin.
2. Connecting Sensors: Use the digital and analog pins to connect sensors. Ensure that the sensors are compatible with the 3.3V logic level.
3. Data Logging: Insert a formatted microSD card into the slot. Use the onboard SD library to write data to the card.
4. Programming: The board is programmable via the Arduino IDE. Select "Adafruit Feather 32u4" from the Boards menu.

• Always ensure that the power supply is within the specified range to prevent damage.
• When using the microSD card slot, make sure the card is formatted correctly (FAT16 or FAT32).
• Disconnect the battery when programming the board via USB to avoid power conflicts.
• Use a regulated 3.3V supply when connecting external components to prevent damage to the board.

#include <SPI.h>
#include <SD.h>

File dataFile;

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // Wait for serial port to connect. Needed for native USB port only
  }

  Serial.print("Initializing SD card...");

  if (!SD.begin(4)) { // Make sure to use the correct chip select pin
    Serial.println("initialization failed!");
    return;
  }
  Serial.println("initialization done.");

  // Create or open the data file
  dataFile = SD.open("datalog.txt", FILE_WRITE);

  // If the file is available, write to it:
  if (dataFile) {
    dataFile.println("Logging data...");
    dataFile.close(); // Make sure to close the file when you're done
    Serial.println("Data written.");
  } else {
    // If the file isn't open, pop up an error:
    Serial.println("error opening datalog.txt");
  }
}

void loop() {
  // Nothing here for now.
}

• SD Card Not Recognized: Ensure the card is properly inserted and formatted to FAT16 or FAT32.
• Board Not Detected by Computer: Check the USB cable and drivers. Press the reset button twice quickly to enter bootloader mode.
• Inaccurate Sensor Readings: Verify that the sensor is compatible with 3.3V logic and is connected correctly.

• If the SD card is not working, try using another card or reformatting the existing one.
• For driver issues, ensure you have the latest drivers installed for the board.
• Double-check all connections and solder joints for continuity and shorts.
• Consult the Adafruit forums and guides for additional support.

Q: Can I power the Adalogger with a 5V supply? A: No, the operating voltage is 3.3V. You must use a regulated 3.3V supply or the onboard USB connection.

Q: How do I program the Adalogger? A: You can program it using the Arduino IDE. Select the "Adafruit Feather 32u4" board from the Boards menu.

Q: What is the maximum size of the SD card that can be used? A: The Adalogger supports microSD cards up to 32GB in size.

Q: Can I use the Adalogger for real-time clock (RTC) applications? A: Yes, the Adalogger has a built-in RTC. You'll need to add a 3V coin cell battery to the board to keep the clock running when power is disconnected.