PID temperature control with Arduino UNO.
If you want to keep something at a certain temperature, say a block of aluminum, you’ll need a thermocouple and some sort of heating element. While you could turn a heater on and off abruptly in a sequence appropriately known as “bang-bang,” a more refined method can be used called PID, or proportional-integral-derivative control. This takes into account how much the temperature is outside of a threshold, and also how it’s changing over time. [via]
PID temperature control with Arduino – [Link]