Bluefruit LE Connect Usage

The Adafruit Bluefruit LE Connect app provides iOS & Android devices with a variety of tools to communicate with Bluefruit LE devices such as the Feather NRF52840. We'll be using Bluefruit LE Connect App to send temperature data using the MQTT protocol to Adafruit IO.

• If you have not yet installed the Bluefruit LE Connect app and set up your phone, follow this page and come back to this page when you're done.

Once installed, open the Bluefruit LE Connect app. The app will automatically begin to scan for nearby Bluetooth LE devices.

Next, you'll need to configure the Bluefruit LE Connect App's MQTT client with your Adafruit IO account information. 

• If you have not done this yet, follow this guide and come back to this page when you're done.

Once configured, tap Connect

The MQTT Status will change to Connected, indicating that you've successfully connected to the Adafruit IO MQTT server.

• If you are not able to connect to Adafruit IO, carefully re-read this guide and try re-connecting.

Code Usage

Viewing Sensor Data on Adafruit IO

Navigate to the Adafruit IO dashboard you created earlier. After 12 minutes have passed, the gauge and line block will update with the current temperature reading every minute. The line graph block updates and display the previous four hours of temperature data.

Fever Notifications

The reactive trigger you set up earlier will email you if the temperature increases beyond a temperature threshold.

If the temperature increases above the threshold you set, the Gauge block will change from a cool blue to bright yellow.

Configure the Fever Temperature Threshold

The Feather NRF52840's built-in NeoPixel will glow bright red if the temperature is above a configurable fever threshold. To change this value in the code, change the following line from:

// Maximum temperature value for armband's fever indicator

// NOTE: This is in degrees Fahrenheit

float fever_temp = 100.4;

to 

// Maximum temperature value for armband's fever indicator

// NOTE: This is in degrees Fahrenheit

float fever_temp = DESIRED_FEVER_TEMPERATURE;

Change the Sensor Read Delay

By default, the code sends data to Adafruit IO every minute, then puts the temperature sensor and the NRF52840 to sleep.

If you want to change this code to read data at faster or slower intervals, change the following line from:

// Sensor read delay, in minutes

int sensor_delay = 1;

to

// Sensor read delay, in minutes

int sensor_delay = DESIRED_SENSOR_DELAY;

Keep in mind that every time the loop is executed, the microcontroller wakes up, executes code, and wirelessly sends data. You may want to increase the delay to conserve power.