My Heart Beats per Minute

Introduction

In this blog, I'll demonstrate how I connected a Heart Rate Sensor to the Avnet MT3620 kit. The Beats Per Minute are calculated and displayed on an attached OLED Display. The RED LED will indicate the users heart beat..

Hardware Configuration

Connecting the Heart Rate Pulse Sensor

Since we're using the Avnet Azure Sphere Starter Kit, We will be putting the 3 leads from the Heart Sensor into boards headers on the Click Socket #1.

The sensor is very simple with three legs:

Heart Rate Sensor

• BLACK: Ground
• RED: Input: +3V or +5V
• PURPLE: Signal

The Click Socket #1 and the color of the Sensor lead connected to it

• PIN AN - PURPLE lead
• PIN +5V - RED  lead
• PIN GND - BLACK lead

See the pinout table below. For Pin AN the Name used in code is GPIO42_ADC1

Connecting the OLED Display

You will need to solder a header to the board. This is how I did mine using a 4 pin header I had lying around.

Solder a 4 pin header to the OLED Interface on the Board.

Code

The code for this project s located on a GitHub repository located here:

https://github.com/skruglewicz/MyBPM

This is built on the 20.04 Sphere SDK and is running Azure Sphere OS version 20.04 Update 2.

Some of the Heart sensor code was ported from a Raspberry PI project that I used to learn about the sensor.

I describe some details along with project links in the following document:

https://www.element14.com/community/docs/DOC-94898/l/sphere-adc-document#jive_content_id_RasPI_Project

The Github repo is here:

https://github.com/WorldFamousElectronics/Raspberry_Pi/tree/master/PulseSensor_C_Pi

This project is working great for me on a Raspberry PI. Here is the link to the project from the vendor of the Heart Pulse sensor.

https://github.com/WorldFamousElectronics/Raspberry_Pi/blob/master/PulseSensor_C_Pi/PulseSensor_C_Pi.md

For the ADC coding I used the

Microsoft High Level ADC Example

https://www.element14.com/community/external-link.jspa?url=https%3A%2F%2Fgithub.com%2FAzure%2Fazure-sphere-samples%2Ftree%2Fmaster%2FSamples%2FADC%2FADC_HighLevelApp

For OLED Code I used the codebase from the blog post

Avnet Azure Sphere Starter-Kit: Advanced Tutorial

https://www.element14.com/community/groups/azuresphere/blog/2019/08/01/azure-sphere-starter-kit-advanced-tutorial

Build and Run the project

See the following Azure Sphere Quickstarts to learn how to build and deploy this sample:

• with Visual Studio https://docs.microsoft.com/azure-sphere/install/qs-blink-application
• with VS Code https://docs.microsoft.com/azure-sphere/install/qs-blink-vscode
• on the Windows command line https://docs.microsoft.com/azure-sphere/install/qs-blink-cli
• on the Linux command line https://docs.microsoft.com/azure-sphere/install/qs-blink-linux-cli