I wanted them to be able to check the temperature and humidity of the room both by checking an LCD display in the room and also via a web page. I put together an Arduino with a DHT11 sensor, 16x2 LCD display and ENC28J60 Ethernet module. I did the project in stages first getting the DHT11 portion working using the DHT11 library and examples from Adafruit, then adding an LCD display and finally adding Ethernet using the EtherCard library and modifying their example code . This makes troubleshooting a lot easier and I could build/learn the code as I went along. I have taken code from the various examples provided with the necessary libraries.
This instructable will go through the steps to prototype this.
Note: the DHT11 sensor isn't very accurate - about plus and minus 2 degrees Celsius and 5% accuracy for humidity. I'll probably be changing to a DHT22 which is plus and minus .5 degrees Celsius and between 2% and 5% for humidity. The good news is it's an easy change in the code.
- An Arduino
- DHT11 or DHT22 sensor from Adafruit or various ebay vendors
- 10K resistor for the DHT11 pullup
- 16x2 LCD display HD44780
- 10k trimpot for LCD contrast
- 100 Ohm resistor for the LCD backlight
- ENC26J60 Ethernet module or shield
- Prototype shield if you use a regular Arduino and ENC28J60 Ethernet shield
- hookup wire, breadboard etc for prototyping