This is a third project in our chipKIT tutorial series and today we are going to construct a simple pulse rate meter using our Easy Pulse sensor with Digilent’s chipKIT Uno32 board. Digilent’s chipKIT Basic I/O shield is also used in this project for displaying the pulse waveform and the pulse rate.
What do we need?
In order to build this project, we will need following things.
- 1 Easy Pulse sensor
- 1 chipKIT Uno32 board
- 1 chipKIT Basic I/O Shield
- 3 male/female jumper wires (20 cm long)
- Power supply source (9V DC wall adapter or battery with a clip)
Besides, a USB cable (not shown in the picture above) is also required to upload the firmware from PC to the Uno32 board.Where to Buy Easy Pulse Sensor?US customers buy here
Wire Connections and Setup
The OLED display on the Basic I/O Shield is driven through SPI interface. This requires the JP4 jumper on chipKIT Uno32 board be placed on the RG9 position so that the SPI SS function is available on Pin 10. Read our tutorial Exploring the chipKIT Uno32 for more details on jumper functions and settings on the Uno32 board. The following picture shows the required jumper settings on Uno32 board for this project.
- Now plugin the Basic I/O shield on top of the Uno32 board and connect the Easy Pulse sensor power supply and the analog PPG output pins to the I/O shield as shown in the following figure.
- The Easy Pulse board is powered with 3.3V power supply from the I/O board header pins. The analog pulse output from Easy Pulse is connected to analog pin A1 of Uno32 through headers available on the I/O shield. The analog pin A0 of Uno32 may not be used for feeding Easy Pulse output because it is already hard-wired to the potentiometer output on the I/O shield. The following picture shows the complete setup of this project.
- Project sketchThe firmware of this project is based on the same algorithm as used in out previous project PC-based heart rate monitor. The algorithm used by the PC application before is now implemented in the firmware of Uno32. The following flowchart shows the algorithm used to compute the pulse rate. For more detail on this algorithm, visit the PC-based heart rate monitor project.