Oct 1, 2017

Version 2 of Compost Professor used a web-based GUI to inform users of the status of their compost, and actions they needed to take. I initially planned to make the GUI a phone application that would provide information via Bluetooth... however, based on my own experiences, I went a different direction.

In my house, my kids are responsible for putting our kitchen scraps into the compost bin (it's one of their chores). I can barely get them to do their chores... there was NO WAY that they were going to look at a phone app to determine if they should add "green", water the compost, or stir the compost. 

So I went with a battery powered "kitchen" unit that provides explicit directions on the screen.

There are still a few things to work out:

1. The voltage divider that I use to read the battery status slowly drains the battery. I added a capacitor is series with one of the voltage divider sensors (as recommended on another site), but I don't think it's going to do. Ultimately I think I'll use a transistor to turn "on/off" the voltage divider
2. I'm using an ESP8266 - primary because of the low cost. I'm thinking of switching to sending data via radio packets (to the "base hub, which has internet and RFM69 capability). I believe this will help with battery management as well.
3. I put the ESP8266 into deep sleep, but that means it's about 3 seconds to "wake-up" the device. Might not seem like a long time, but it is when you're standing at the counter waiting to take scraps outside after dinner.
4. The TFT screen back-light stays on even when the ESP8266 is asleep. There weren't great options to deal with that on the prototype TFT screen I am using. Other TFTs require a pin to pull HIGH for the back light to turn on... this would resolve the problem.