This project is to control a 12V fan connected to a bottom vent of my Weber Smokey Mountain smoker. Everything is running on a RaspberryPi which is powered with a 10000mAh mobile battery pack.
When the temperature falls below a threshold, the fan turns on to heat up the charcoal. When it hits another threshold, the fan shuts down.
There is also a sqlite3 database of all of the past temperatures for plotting using the google chart API
The temperature probe is a Maverick ET-73 replacement probe from Amazon.
Ice water, room temp water, and boiling water was used to find 3 data points of resistance/temp. I then solved the system of equations to model it after the Steinhart-Hart equation for resistance. The coefficients matched the curve pretty well.
I then used a voltage divider with a 10k ohm fixed resistance to read the probe into the A2D chip. I used a MCP3008 a2d which is a 10 bit 8 channel ADC with SPI.
SPI was then used to interface between the a2d and the raspberry pi
