How to Use Adafruit Feather nRF52840 Sense: Examples, Pinouts, and Specs

The Adafruit Feather nRF52840 Sense (Part ID: 4516) is a compact and versatile microcontroller board designed for IoT, wearable, and sensor-based applications. Powered by the Nordic nRF52840 chip, it features Bluetooth Low Energy (BLE) capabilities, built-in sensors, and Feather ecosystem compatibility. This board is ideal for projects requiring wireless communication, environmental sensing, or advanced data processing in a small form factor.

• IoT devices and smart home applications
• Wearable technology
• Environmental monitoring (e.g., temperature, humidity, air quality)
• Prototyping BLE-enabled devices
• Machine learning on microcontrollers (TinyML)

The Adafruit Feather nRF52840 Sense is packed with features to support a wide range of applications. Below are its key technical details:

• Microcontroller: Nordic nRF52840 (ARM Cortex-M4F @ 64 MHz)
• Wireless Connectivity: Bluetooth 5.0 Low Energy (BLE) and NFC
• Flash Memory: 1 MB
• RAM: 256 KB
• Operating Voltage: 3.3V
• Power Supply: USB-C or LiPo battery (3.7V)
• Sensors:
  • LSM6DS33: 6-DoF IMU (accelerometer + gyroscope)
  • LIS3MDL: 3-axis magnetometer
  • SHTC3: Temperature and humidity sensor
  • APDS9960: Proximity, light, color, and gesture sensor
  • PDM microphone for audio input
• Dimensions: 51mm x 23mm x 8mm
• Weight: 5.5g

The Feather nRF52840 Sense has a standard Feather form factor with 20 GPIO pins. Below is the pinout description:

The Adafruit Feather nRF52840 Sense is easy to use and integrates seamlessly with the Arduino IDE, CircuitPython, or other development environments. Below are the steps to get started:

1. Install the Required Software:

   • Download and install the Arduino IDE or CircuitPython.
   • Add the Adafruit nRF52 Board Support Package (BSP) to the Arduino IDE via the Boards Manager.
   • Install the necessary libraries for the sensors (e.g., Adafruit Unified Sensor, Adafruit LSM6DS33, etc.).

2. Connect the Board:

   • Use a USB-C cable to connect the board to your computer.
   • Ensure the board is powered via USB or a connected LiPo battery.

3. Select the Board and Port:

   • In the Arduino IDE, go to Tools > Board and select Adafruit Feather nRF52840 Sense.
   • Under Tools > Port, select the appropriate COM port.

The following Arduino sketch demonstrates how to read data from the onboard temperature and humidity sensor (SHTC3):

#include <Wire.h>
#include "Adafruit_SHTC3.h"

// Create an SHTC3 object
Adafruit_SHTC3 shtc3 = Adafruit_SHTC3();

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10); // Wait for Serial Monitor to open

  Serial.println("Adafruit Feather nRF52840 Sense - SHTC3 Example");

  // Initialize the sensor
  if (!shtc3.begin()) {
    Serial.println("Failed to find SHTC3 sensor!");
    while (1) delay(10);
  }
  Serial.println("SHTC3 sensor initialized.");
}

void loop() {
  sensors_event_t humidity, temp;

  // Get temperature and humidity data
  if (shtc3.getEvent(&humidity, &temp)) {
    Serial.print("Temperature: ");
    Serial.print(temp.temperature);
    Serial.println(" °C");

    Serial.print("Humidity: ");
    Serial.print(humidity.relative_humidity);
    Serial.println(" %");
  } else {
    Serial.println("Failed to read data from SHTC3 sensor.");
  }

  delay(2000); // Wait 2 seconds before the next reading
}

• Power Supply: Ensure the board is powered by a stable 3.3V source or a fully charged LiPo battery.
• Sensor Libraries: Use the Adafruit Unified Sensor library for consistent sensor data handling.
• BLE Applications: For BLE projects, use the Adafruit Bluefruit library to simplify BLE communication.
• Firmware Updates: Periodically check for firmware updates to ensure compatibility and access to new features.

1. Board Not Detected in Arduino IDE:

   • Ensure the correct board and port are selected in the Tools menu.
   • Check the USB cable (some cables are power-only and do not support data transfer).

2. Sensor Data Not Reading:

   • Verify that the required libraries are installed.
   • Check the wiring if using external sensors.

3. BLE Connection Fails:

   • Ensure the BLE device is within range.
   • Restart the board and the BLE device to reset the connection.

• Reset the Board: Press the reset button if the board becomes unresponsive.
• Debugging: Use the Serial Monitor to print debug messages and identify issues.
• Library Updates: Regularly update the Adafruit libraries to ensure compatibility with the latest firmware.

By following this documentation, you can effectively utilize the Adafruit Feather nRF52840 Sense for a wide range of applications. Happy prototyping!