The Problem: In years past, I've used an incandescent bulb to help keep the two chickens in my backyard warm though the cold New Hampshire winters (the top's of their heads, their combs, get frostbit when it gets really cold). Just enough light would filter out of the coop so that I could tell from the view from my kitchen that the light was on, keeping the chickens warm. The downside is that the extra light throws off their bodies' natural rhythm, so this year I'm want to use a ceramic heater bulb, the kind you might use in a reptile terarium. It gives off no light, so I don't have a good way to tell if the heater is functioning. I need a way to measure the temperature of the coop.
Solution: Design and build a temperature sensor PCB for the inside and outside of the coop automatically send the results to my computer.
I chose the ESP8266 to be the main microcontroller for this project. It's one of the hottest (and easiest) Internet of Things microcontroller on the market today. Originally developed as an easy solution for adding WiFi to existing projects, its actually a powerful microcontroller itself, able to act as both a ethernet client or server for your next DIY electronics project. Its supported as an Add-On board for your Arduino environment.
The easiest way to get started is with the Adafruit HUZZAH ESP8266 Breakout board, which can be had for under $10 dollars
The custom PCB is compatible with the Adafruit HUZZAH ESP8266 Breakout. We'll go into a detailed explanation of the design of this board next, or you can jump right to the sections your may be interested in:
The daughter board is really an easy way to hook up multiple temperature-sensitive resistors to the analog-to-digital converter of the ESP8266. For this chicken-coop project, we need to measure the inside and outside temperature. The daughter board supports measuring up to 4 temperatures. Since we only have two temperatures to measure, we'll need two 10K Precision Epoxy Thermistors from Adafruit
You'll need a way to talk to the ESP8266 and program it. I used the SparkFun USB to Serial Breakout - FT232RL
We want to be able to have this setup run off the grid. This 6V 3.4W Solar panel - 3.4 Watt Panel is a reliable solar panel that's available from Adafruit for $39
We want to be able to run the sensor at night. The sensor also consumes about 200mA, which is at the upper limit of the solar panel. So we'll setup this project to use a battery as its primary power source, and use the solar panel to charge the battery. This will let the sensor run through the night and in cloudy weather and when its shady. Adafruit offers a variety of batteries of different capacities. The Lithium Ion Polymer Battery - 3.7v 2500mAh is a large-ish battery that will work for this project and many others for $14.95
To charge the battery, we need a charging circuit. The USB LiIon/LiPoly charger at only $12.50 from Adafruit is a versitile solution for this project, and just like the battery, many other projects you might want to do.