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

The Adafruit Feather 32u4 Bluefruit is an all-in-one microcontroller and Bluetooth Low Energy (BLE) development board. It is part of the Feather ecosystem - a complete line of development boards from Adafruit that are both standalone and stackable. They're able to be powered by a variety of battery options and are equipped with built-in USB charging. This board is ideal for makers and hobbyists who want to add wireless connectivity to their projects with ease.

• Wearable electronics
• Wireless sensor networks
• IoT devices
• Bluetooth-enabled robotics
• DIY smart home devices

• Microcontroller: ATmega32u4
• Operating Voltage: 3.3V
• Input Voltage: 3.7-6V via battery and up to 12V via the USB pin
• Clock Speed: 8 MHz
• Digital I/O Pins: 20
• PWM Channels: 7
• Analog Input Channels: 12
• DC Current per I/O Pin: 10 mA
• Flash Memory: 32 KB (ATmega32u4) of which 4 KB used by bootloader
• SRAM: 2.5 KB (ATmega32u4)
• EEPROM: 1 KB (ATmega32u4)
• Bluetooth: Bluetooth 4.0 Low Energy (BLE)

1. Powering the Board:

   • You can power the Adafruit Feather 32u4 Bluefruit via the USB connection or with an external battery.
   • The board has a built-in charging circuit for a 3.7V LiPo battery.

2. Programming the Board:

   • The board is programmable via the Arduino IDE. Select "Adafruit Feather 32u4" from the Tools > Board menu.
   • Use a micro-USB cable to connect the board to your computer.

3. Connecting Bluetooth:

   • The board can be used as a BLE client (peripheral) or server (central).
   • Use the Adafruit Bluefruit LE Connect app to connect and communicate with the board.

• Antenna Design: Ensure that the BLE antenna is not obstructed by metal to maintain signal strength.
• Power Management: Use the EN pin to disable the 3.3V regulator when running on battery power to conserve energy.
• I/O Voltage: All pins are 3.3V logic. Do not input more than 3.3V to any I/O pin to avoid damage.

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_BLE.h>
#include <Adafruit_BluefruitLE_SPI.h>

// SHARED SPI SETTINGS (see Adafruit_BLE_SPI.h for definitions)
#define BLUEFRUIT_SPI_CS               8
#define BLUEFRUIT_SPI_IRQ              7
#define BLUEFRUIT_SPI_RST              4    // Optional but recommended, set to -1 if unused

// Create the bluefruit object, using SPI interface
Adafruit_BluefruitLE_SPI ble(BLUEFRUIT_SPI_CS, BLUEFRUIT_SPI_IRQ, BLUEFRUIT_SPI_RST);

void setup() {
  Serial.begin(115200);
  Serial.println(F("Adafruit Bluefruit Feather 32u4 Basic Demo"));
  Serial.println(F("-----------------------------------------"));

  // Initialise the module
  Serial.print(F("Initialising the Bluefruit LE module: "));

  if (!ble.begin()) {
    Serial.println(F("Couldn't find Bluefruit, make sure it's in CoMmanD mode & check wiring?"));
  }
  Serial.println(F("OK!"));

  // Perform a factory reset to make sure everything is in a known state
  Serial.println(F("Performing a factory reset: "));
  if (!ble.factoryReset()) {
    Serial.println(F("Couldn't factory reset"));
  }

  // Set BLE UART baud rate to default
  ble.echo(false);
  ble.info();
  ble.verbose(false);  // Turn off verbose mode for lower debug output (optional)
}

void loop() {
  // Placeholder for user code.
}

• Device Not Recognized: Ensure the micro-USB cable is properly connected and the computer recognizes the USB device.
• Unable to Upload Sketches: Check that the correct board and port are selected in the Arduino IDE.
• Bluetooth Connection Issues: Make sure the BLE antenna is not obstructed and the device is charged.

• Reset the Board: Press the reset button on the board twice quickly to enter bootloader mode if the board is not recognized.
• Check Battery Connection: If using a battery, ensure it is properly connected and charged.
• Update Firmware: Ensure the board's BLE firmware is up to date using the Bluefruit LE Connect app.

Q: Can I use the Adafruit Feather 32u4 Bluefruit with my smartphone?

A: Yes, you can use it with both iOS and Android devices using the Adafruit Bluefruit LE Connect app.

Q: What is the range of the Bluetooth connection?

A: The BLE range is typically up to 10 meters (33 feet), but it can vary depending on obstacles and interference.

Q: How do I update the BLE firmware?

A: You can update the firmware using the Adafruit Bluefruit LE Connect app. Follow the instructions within the app to complete the update.

Q: Can I use the Adafruit Feather 32u4 Bluefruit with external sensors?

A: Yes, the board has multiple analog and digital I/O pins that can be used to connect a variety of sensors and peripherals.