Project Introduction

Background 

After finishing many treadmill runs only to find the calculated distance and pace recorded by my Garmin watch differed from the treadmill display by quite a bit, I decided to do something about it.
Garmin states:

When running with GPS turned off, speed and distance are calculated using the accelerometer in the device. The accelerometer is self-calibrating. The accuracy of the speed and distance data improves after a few outdoor runs using GPS.

I've found that it never quite handles varying paces very well. Doing a few similar evenly paced runs outdoors "taught" the watch to use an indoor pace close to the outdoor pace. But when the treadmill speed varied from that usual outdoor pace, the discrepancies increased.

Additionally, I've always found running on my treadmill to be significantly more difficult than running outdoors. Was it a change in running style? Was it a difference in temperature or wind cooling? Was the speed of the treadmill off? I had no idea at the time, but it was always in the back of my mind.

So after deleting recorded activities only to replace them with manual entries matching the speed and distance reported by the treadmill (only when the watch was slower, of course 😉... unfortunately, it usually was), I looked for a solution to the problem. I'm a software developer and avid electronics tinkerer, so I saw this as an opportunity to learn some new skills and to come up with a relatively inexpensive solution using some parts I already had lying around the house.

A Solution  

Garmin watches use a wireless protocol known as ANT+ to communicate with various external sensors. The goal of this project was to develop a sensor to integrate with my treadmill for recording speed and distance and to report those details to a Garmin watch using ANT+. Ideally the solution would require no additional programming on the watch through ConnectIQ, simplifying the set up and providing a cleaner integration.

The solution that was developed uses a 2.4 GHz development board capable of sending and receiving ANT+ messages and an infrared obstacle detection sensor to mimic an ANT+ foot pod sensor. Best of all, it costs only around $15 US and is relatively easy to assemble.

The series of posts on this blog are going to document the steps taken to develop this solution, talking not only about the technical details for recreating the sensor shown above but also the reasons behind some of the decisions that were made, current limitations, and areas that this project could be improved. Stay tuned for all of the details. This is going to be a long one.

Next up, we're going to open up the box and take a look at all of the parts used.