PID (Proportional-integral-derivative) controller for C and C++ languages
A proportional–integral–derivative controller (PID controller or three-term controller) is a control loop mechanism employing feedback that is widely used in industrial control systems and a variety of other applications requiring continuously modulated control. A PID controller continuously calculates an error value e ( t ) {\displaystyle e(t)} as the difference between a desired setpoint (SP) and a measured process variable (PV) and applies a correction based on proportional, integral, and derivative terms (denoted P, I, and D respectively), hence the name. (Wikipedia)
A block diagram of a PID controller:
(Wikipedia)
First, create and initialize the controller.
PIDctrl_t PID; // create PID controller
struct PIDctrl_config PIDconfig = {kP: 0.05, kD: 0.3, kI: 0.0001, timestep: 1, minOut: -65535, maxOut: 65535}; // Configuration structure
while (!PIDctrl_Init(&PID, PIDconfig)) {} // This code will try to initialize the controller until successUse PIDctrl_Calculate() to calculate controller value.
// Arduino example
double sensor_value = analogRead(3); // Read sensor measurement
double PID_out = PIDctrl_Calculate(&PID, 32, sensor_value); // calculate PID output value; 32 is setpoint
analogWrite(9, PID_out); // Write value to pin
// Don't forget to set minOut and maxOut to -255 and 255 for Arduino's analogWrite() function