Maker Hardware to the Rescue
Polar Heart Rate monitor systems work with horses. I learned this from a client who contacted me in the fall of 2013 to develop a set of equine heart rate monitors with a RF interface. The client wanted ten systems designed, coded and built in a little over two weeks. I was able to meet this aggressive schedule using mostly off-the-shelf modules from Adafruit and Sparkfun, along with a small amount of custom circuitry. Arduino libraries made interfacing with an OLED display much easier. The complete firmware required only about 1500 lines of C and included a bit-mapped interface, configuration menus, power management and control. Although one would not want to go to mass production using these components, the project would not have been possible without maker modules.
Transmitter electronics consisting of my HRMI, Rechargeable LiPo power system, an Arduino micro-controller and XBee digital radio.
Detail of the XBee Radio shield with custom circuitry for battery level sense, user interface and power management.