File content as of revision 0:873985df821c:

#include "PID.h"

PID::PID(Timer *T)
{
    integral         = 0;
    last_error       = 0;
    current_time     = 0;
    last_time        = 0;
    
    timer = T;
    timer -> start();
}

float PID::controlPID(float target, float current)
{
    current_time = timer -> read();
    float error = target - current;
    float dt = current_time - last_time;
    integral += ( error + last_error ) / 2 * dt;
    float differential = ( error - last_error ) / dt;
    float control = Kp * error + Ki * integral + Kd * differential;
    last_error = error;
    last_time = current_time;
    return control;
}

float PID::controlP(float target, float current, float new_Kp)
{
    float error = target - current;
    float control = new_Kp * error;
    return control;
}
float PID::controlPI(float target, float current)
{
    current_time = timer -> read();
    float error = target - current;
    float dt = current_time - last_time;
    integral += (error + last_error) / 2 * dt;
    float control = Kp * error + Ki * integral;
    last_error = error;
    last_time = timer->read();
    return control;
}
void PID::setParameter(float new_Kp, float new_Ki, float new_Kd)
{
    Kp = new_Kp;
    Ki = new_Ki;
    Kd = new_Kd;
}
void PID::setParameter(float new_Ku, float new_Pu)
{  
    Ku = new_Ku;
    Pu = new_Pu;
    
    Kp = 0.60 * Ku;
    Ti = 0.50 * Pu;
    Td = 0.125 * Pu;
    Ki = (1 / Ti) * Kp;
    Kd = Td * Kp;
}
void PID::setParameterPI(float new_Ku, float new_Pu)
{
    Kp = 0.45 * Ku;
    Ti = 0.83 * Pu;
    Ki = (1 / Ti) * Kp;
}
void PID::reset()
{
    integral    = 0;
    last_error  = 0;
    last_time = timer -> read();
}