Trello integration for Garmin devices. Includes smartwatch application and NodeJS based backend, with UI based on BackboneJS.

Motivation

Having used Fitbit One since 2012, I decided to finally try different sports tracker.
The choice was a newly released in April 2016 Garmin vívoactive® HR.

It’s a brilliant watch, with many smartwatch functions (calls, notifications etc.), impressive selection of supported sports (smimming was the big one for me as I swim indoor a lot), and a built-in GPS.

The one feature it doesn’t support though (at least at the time of writing) is customised workouts. What I wanted is an easy way to prepare a set of exercises together with durations, and play them on my watch as I exercise.

Good example of such a workout would be 7 min workout or different variations of it. Timing matters, and you have some 13-15 exercises to remember.

What it is

This project was to integrate Trello with Garmin devices.

Workouts can be easily defined in Trello (see this example public board) as a sequence of cards in a list. Trello board can have many lists. Every list is a separate sequence (e.g. separete workout).
Note, how durations for each element of the workout sequence are defined using simple [XXm YYs] text added to the card summary:

To achieve seamless integration with Garmin watches, it required:

1. Writing a web based backend and frontend that integrated with Trello using their REST API.
   Garminello backend is hosted on heroku.
   The main purpose of backend is to:
   • user registration (using passport)
   • communicate with Trello on behalf of the user (using OAuth token)
   • translate Trello results (e.g. optimise response size for watch, interpret duration data)
   • authenticate registered user watches
   • expose REST API for the watches to use
2. Writing an Connect IQ app which would communicate with the backend.
   The app is available at Garmin IQ Shop.

The diagram below shows state changes of the app:

Challenges

• Programming for a very resource constrained device using fairly limited C++ - like language - Monkey C.
• As someone starting NodeJS development I was overwhelmed by the number of frameworks and build tools available for the platform.
  It took longer to decide on technology than to actually implement the system.

Lessons learned

• NodeJS - my first project using Express framework.
• JavaScript ES6 - this is the first project where I had a chance to use ECMAScript 6 specification. Thanks to Babel project (and babelify for browserify) this was pretty easy.
• Web backend is Dockerised. Launching NodeJS and PostgreSQL based backed locally is a matter or running docker-compose.
• Hosting and monitoring using heroku.