Come winter time, the hackerspace can get kind of cold. And in the summer, it can get darn hot! To give members a heads up of the current temperature in the ‘space before making the journey out here, we created a web-enabled temperature/humidity sensor.
The main device is an ESP8266 which reads a DHT-22 sensor. The temperature and humidity information is sent up to thingspeak.com. From there, a quick PHP script in our WordPress Widgets section can read and display the current temperature on the website. Since the DHT-22 can also do humidity, we opted for displaying that as well. Visiting the thingspeak page shows a graph of historical data.
The hardware is super simple. A custom milled PCB breakout board holds the ESP8266, the DHT-22 and a couple of screw terminals for a 3.3vdc supply. Since we couldn’t find a wall-wart with close to 3.3v, we opted for a 12 volter with an adjustable voltage regulator. Both PCBs were just glued to the wall-wart which was plugged into a ceiling outlet to keep it out of the way. Simple and effective!
On the right side of our webpage, check out the displayed data, it’s updated every minute:
Below is what the Thingspeak historical data looks like: