We have a refrigerator downstairs that once in a while gets left open, and since it's downstairs, we sometimes don't catch it in time to save to food. Will and I decided to make something to help solve this.

Our plan is to use our Particle Proton (a tiny Wi-Fi development kit) and connect a temperature sensor. We'll report that temp to "the cloud" and if the temp rises above some threshold, we'll use IFTTT to text or call us to let us know to check the fridge.

I got us a free DS18B20 temperature sensor as a sample from Maxim Integrated (how cool is that?) and found some nice sample code here.

The prototype is now sitting in the fridge (photo above), dutifully sending out the temp every 10 seconds. The code is crazy simple.

Things we talked about while doing this:

• Resistors in parallel and in series
• Reading resistors
• Analog-to-digital conversion
• What numbers look like in binary
• Trusting a component's data sheet first
• How to debug when Papa tells you to put the resistor in the wrong place

UPDATE: The 2200mAh 3.7V battery didn't last until morning, so Next up will be to see whether there's a way to reduce power consumption. Fewer temp reports to the cloud will obviously help. I wonder if there's a "low power mode".