PROCESS

Step 1: Controlling Hardware

Since we had to control two servos and an RGB LED, we had an issue with having too few pins for PWM. We accidentally used pins that shared the same PWM timer, which was causing glitches. When we switched to the TX and RX pins, the issue resolved.

We also had trouble understanding how to control the servos without burning them out. They don't like zero or 180 degree positions, so we constrained them to between 5 and 175 degree positions.

Step 2:  Pulling Data from Google Sheets

We looked at ways to create a simple web service to take Google Sheets data, digest it, and return a desired output. We ended up publishing the Google Sheets data as a live CSV file, and then used an existing PHP library for processing CSV files to manage the data. We then set up a web hook that pulls the data from the aforementioned PHP file and returns it to the Particle. Once on the Particle, the data string is parsed. 

Step 3: Physical Prototyping

As mentioned in our PROJECT section, we originally wanted to prototype this design in the form of a full-circle clock. However, since the hands need to move independently of each other, geometric constraints would keep it from working even if we used 360 servos. The solution is to use concentric drive shafts that are independently controlled by the two servos, but the mechanical complexity of this solution is outside the scope of this project.