Connect Pulse Sensor to Raspberry Pi with Arduino!
- Pulse Sensor
- Raspberry Pi (we use a RasPi 3 B)
- Arduino compatible microcontroller board
- USB cable
There are many was to set up your Pi. We used Adafruit's tutorial to get set up. Once you have the Pi OS up and running, you will want to make sure that your configuration settings allow us to connect the Arduino. In the GUI, select Raspberry Pi Configuration, then open the Interfaces tab and enable Serial Port. This process may require you to restart your Pi.
To do this on the command line, you need to edit your config file. Open a terminal window and type in
sudo raspi-config
This will open up a configuration panel. Use the arrow keys to move down to Interfacing Options then press the right arrow to highlight <Select> and press either the space bar or Enter/Return.
In the next pane, arrow down to the Serial Port option and enable it.
Pi may ask you to reboot, so go ahead and do that, otherwise arrow your way to <Finish> and get out of the config menu.
Now it's time to install the Arduino IDE. Before we do that it's best to make sure that you have the latest. Open a terminal window and type in
sudo apt-get update && sudo apt-get upgrade
This might take a moment. When it's done, open up a web browser on the Pi and go to
https://www.arduino.cc/en/Main/Software
Click on Linux ARM 32 bits to download it to your Downloads folder. Wait just a sec for it to download. Now you have a zipped up Arduino file in your Downloads folder. To unzip it, go back to the terminal window and move to the Downloads folder by entering cd Downloads then enter ls to make sure you get the right file name to extract. When I wrote this, the version was 1.8.9 your version may differ. On the command line, enter
tar -xf arduino-1.8.9-linuxarm.tar.xz
to extract the folder. It will take a moment... When it's extracted move it to the opt directory, because that's a better place for this folder to live. Enter
sudo mv arduino-1.8.9 /opt
It's time to do the installation! In terminal enter
sudo /opt/arduino-1.8.9/install.sh
Raspberry Pi will install the Arduino IDE. Fabulous! You will find an option to run Arduino when you go to the Programming tab in the main menu of RasPi. Open Arduino, and once it is running we want to install the latest PulseSensor Playground Library. Click on
Sketch > Include Library > Manage Libraries
Once the Manager has settled down, type PulseSensor into the search field and the PulseSensor Playground Library will pop up.
Install the latest version, and we're ready to program Arduino!
For this example, we're going to use an Arduino Uno. The playground works with just just about everything. If you're having trouble connecting Pulse Sensor with anything, please use the issues tab. If this is your first time using Pulse Sensor, check out our handy guide for getting your Pulse Sensor set up to read beats. We also have lots of tutorials.
Plug your Arduino into an unused USB cable on RasPi. Then open up Arduino IDE, and select the PulseSensor_BPM sketch from the examples folder.
Now, you have to select the serial port that your Arduino UNO is connected to. Click Tools > Port to find the right one. UNO is easy to find.
Press the upload button on Arduino IDE to upload the sketch.
This example sketch is designed to send pulse data right to the Arduino Serial plotter. Once it's uploaded, click on Tools > Serial Plotter to open it up and see the plot. NOTE: make sure that the baud rate is set to 115200 in the bottom right corner of the Serial Plotter!
This pulse signal is a bit noisy. That's because the power coming out of the USB on the RasPi is pretty noisy. To fix this, you can run the Pulse Sensor on 3V. Here's how you do that.
First, you need to make sure that Arduino and Pulse Sensor are working at 3.3V. I'm going to use a breadboard and some jumper wires to set this up. Find the 3.3V pin on the Arduino, and connect it to the breadboard red rail. Then also connect the Arduino AREF pin to the breadboard red rail. This will show Arduino how you want to measure analog signals. Connect the Pulse Sensor as usual, but make sure that the Pulse Sensor red wire is connected to the breadboard red rail. Here's a fritzing diagram to help you out.
The last thing you have to do, is tell the Arduino that we want it to read the AREF pin when it reads analog signals. Put the following code into the setup() of the PulseSensor_BPM example sketch.
analogReference(EXTERNAL);
Then upload to the UNO. Now, when you open the Serial Plotter, you will see a much cleaner signal.
