I have a chest freezer that I wanted to get alerts for if the temperature got too high.
I built a little protoboard based setup. It uses a 10 pin ribbon cable and a 2x5 header to connect 3 TMP36 sensors. I have one outside the freezer one at the top and one at the bottom. The Photon samples the temps once every second and keeps a 5 minute rolling window of values. Once every 15 seconds it pushes the sensor values to ThingSpeak which has rules setup to tweet me if the freezer gets too warm.
- Finished Photos
- Source Code
- PCB Schematic
- Probe Wiring - follow the schematic on the top-left of page 11. I wired the resistors and capacitor in a little bundle with the TMP36 and wrapped the whole thing in heat-shrink.
It isn’t a pretty package but it works can can easily be expanded to quite a few sensors hanging off a single Photon.