The quad is old. Each room has an individually controllable radiator connected to the central heating system. The radiator's control mechanism consists of a fan and a simple dial-thermostat which is capable of maintaining a set temperature by modulating the speed of the fan. It cannot be programmed or set remotely.
What it does
TextTemp allows the user to interact with a retro-fitted, remotely operable thermostat. The user is able to send an SMS, telling the radiator to get the room to a given temperature.
How we built it
TextTemp consists of a Fona808 (2G cellular network connectivity board), an Arduino Uno, and a standard SG 5010 servo motor.
Challenges we ran into
We first attempted to use Twilio to send and receive SMS messages. However, Twilio's receive back-end requires a web server to parse output, and send the output on to requisite devices. This was deemed too complex for a project of this scope, leading to the choice of the Fona808 as an alternative to Twilio and Ngrock.
Accomplishments that we're proud of
In writing the software that runs TextTemp, we coded a minimal parsing library from scratch; this was the first experience either of us had with any sort of parsing. We believe that this is likely to be applicable in later projects.
What we learned
Even if it looks easy, it probably isn't. More concretely though, we learned that a) a fona808 absolutely REQUIRES an external LiPo battery, b) that most SIM cards are (kind of irreversibly) associated with an IMEI, c) ABS over PLA for functional 3D-printed parts (Hades >> The Joker in RPL).
What's next for Text-Temp
If our initial goals are met, we plan to implement a function that allows multiple users to program the thermostat, also through a SMS interface.