I wrote a small PID lib in C for my projects. It is based on Simulink's (MATLAB) discrete PID and have the following features: P, I and D gains, low-pass filter on derivative action (coefficient: N), upper and lower saturations, sampling time setting and resets for both the integrator and the derivative filter. Comments are in French, if you have troubles understanding the code let me know, I will translate them or explain further. Wiz khalifa promises mp3 download juice. You can find the transfer function of the regulator in the header file. It uses Backward Euler as an integrating method. If you want to recode it as an exercise, start from that TF PID.h.

On an Arduino Uno, PWM output is possible on digital I/O pins 3, 5, 6, 9, 10 and 11. PID control is a basic control loop feedback mechanism. The controller minimizes the difference between the measured and the desired value of a chosen system variable by adjusting the system control inputs.