Thermominator

Thermominator is a personal heat monitor. It's a wearable keychain-like device that tracks heat exposure. My team of 8 built this for MIT Office of Sustainability as part of our 6.900 project. I led firmware development.

Sleep is the whole problem

We were building a wearable greatly constrained by its battery. On an ESP32-C3, the difference between a device that lasts hours and one that lasts days is mainly about how aggressively it sleeps.

I wrote the firmware as a C++ state machine between modem sleep, light sleep, and deep sleep, so that the device would sleep as much as possible without trading off too much functionality.

The integration surface

Firmware is where every other subteam's work has to meet: WiFi communication, the sensor stack, LCD display, and our backend server connection.