PID Controller on Arduino for Temperature Chamber

Implemented a PID controller for a small environmental test chamber. The setup: a thermoelectric cooler (Peltier) for both heating and cooling, a DS18B20 sensor, and an Arduino Mega driving an H-bridge.

The Brett Beauregard PID library is the standard reference, but understanding what you're doing matters more than the library. Kp, Ki, and Kd must be tuned for your specific thermal mass and heater/cooler power. Start with Ki and Kd at zero and increase Kp until the system oscillates, then use the Ziegler-Nichols method to calculate starting values for all three.

Antiwindup is essential for a thermal system because temperature changes slowly and integral windup causes massive overshoot. The Brett library handles this with output clamping, but review it for your specific use case. For a tight setpoint hold (±0.2°C in my case) you also need to account for sensor placement — mounting the DS18B20 on the chamber wall rather than in the air gives a more stable feedback signal.