Heart Rate Monitor Downloads

Download PDF Manual: hrmi.pdf (updated to revision 1.1)

Download the code examples in the manual Appendix B:
hrmi_demos.zip (Arduino 0018)

A quick shout out to
François Morin for finding a typo. Check out his very cool use of the HRMI in Elektra10.

Processing Demo

Download source: hrmi_graph.zip (original) hrmi_graph_3.zip updated for Processing 3)

Demonstrates how to access the HRMI through the USB interface using the
Processing development environment. Pressing the "Average" button will put the HRMI into Average mode and display a running heartrate. Pressing the "Raw" button will put the HRMI into Raw mode. Pressing the "Hold" button suspends polling of the HRMI and update of the display but keeps the serial port open. Pressing the "Disable" button closes the serial port (so you can safely unplug the HRMI). Runs on Windows, Mac OS X and Linux machines. The original zip file contains both the source and precompiled binaries for all three platforms. However this code doesn’t work on some modern platforms. The hrmi_graph_3.zip file should compile with Processing 3 (I no longer distribute the precompiled binaries because they are too large but you can create them from within Processing). Be sure to note the name of the serial port driver your system has associated with the HRMI. The hrmi_graph application will display a list of serial port devices it finds on your system and you must select the one associated with the HRMI.

Wiring Demos

(click image for video)
Download: arduino_10bar.zip

This demo drives a 10-segment common anode bar-graph LED with a representation of your immediate heart rate value. It runs on an Arduino (shown here running on the excellent Modern Device "freeduino" clone) and interfaces using I2C. All you need are a couple of 4.7 kohm pull-ups on the I2C lines, the bar-graph display (or 10 discrete LEDs) and a single 180 - 270 ohm current limiting resistor (you only need one because only one LED is ever on at a time).

(click image for video)
Download: arduino_ascii_disp.zip

This demo drives an old Siemens PD3537 intelligent green dot-matrix LED display. It's very easy to drive a modern parallel or serial LCD module using libraries that come with the free and easy-to-use Arduino development system. Or use whatever displays are knocking around your parts drawer.