Discrete PID controller implementation. Set up by giving P/I/D terms to Init_PID(), and uses a struct PID_DATA to store internal values.
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Definition in file pid.c.
#include "pid.h"
#include "stdint.h"
Include dependency graph for pid.c:
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Functions | |
int16_t | pid_Controller (int16_t setPoint, int16_t processValue, struct PID_DATA *pid_st) |
PID control algorithm. | |
void | pid_Init (int16_t p_factor, int16_t i_factor, int16_t d_factor, struct PID_DATA *pid) |
Initialisation of PID controller parameters. | |
void | pid_Reset_Integrator (pidData_t *pid_st) |
Resets the integrator. |
PID control algorithm.
Calculates output from setpoint, process value and PID status.
setPoint | Desired value. | |
processValue | Measured value. | |
pid_st | PID status struct. |
Definition at line 59 of file pid.c.
References PID_DATA::D_Factor, PID_DATA::I_Factor, PID_DATA::lastProcessValue, MAX_I_TERM, MAX_INT, PID_DATA::maxError, PID_DATA::maxSumError, PID_DATA::P_Factor, SCALING_FACTOR, and PID_DATA::sumError.
Referenced by main().
00060 { 00061 int16_t error, p_term, d_term; 00062 int32_t i_term, ret, temp; 00063 00064 error = setPoint - processValue; 00065 00066 // Calculate Pterm and limit error overflow 00067 if (error > pid_st->maxError){ 00068 p_term = MAX_INT; 00069 } 00070 else if (error < -pid_st->maxError){ 00071 p_term = -MAX_INT; 00072 } 00073 else{ 00074 p_term = pid_st->P_Factor * error; 00075 } 00076 00077 // Calculate Iterm and limit integral runaway 00078 temp = pid_st->sumError + error; 00079 if(temp > pid_st->maxSumError){ 00080 i_term = MAX_I_TERM; 00081 pid_st->sumError = pid_st->maxSumError; 00082 } 00083 else if(temp < -pid_st->maxSumError){ 00084 i_term = -MAX_I_TERM; 00085 pid_st->sumError = -pid_st->maxSumError; 00086 } 00087 else{ 00088 pid_st->sumError = temp; 00089 i_term = pid_st->I_Factor * pid_st->sumError; 00090 } 00091 00092 // Calculate Dterm 00093 d_term = pid_st->D_Factor * (pid_st->lastProcessValue - processValue); 00094 00095 pid_st->lastProcessValue = processValue; 00096 00097 ret = (p_term + i_term + d_term) / SCALING_FACTOR; 00098 if(ret > MAX_INT){ 00099 ret = MAX_INT; 00100 } 00101 else if(ret < -MAX_INT){ 00102 ret = -MAX_INT; 00103 } 00104 00105 return((int16_t)ret); 00106 }
Initialisation of PID controller parameters.
Initialise the variables used by the PID algorithm.
p_factor | Proportional term. | |
i_factor | Integral term. | |
d_factor | Derivate term. | |
pid | Struct with PID status. |
Definition at line 35 of file pid.c.
References PID_DATA::D_Factor, PID_DATA::I_Factor, PID_DATA::lastProcessValue, MAX_I_TERM, MAX_INT, PID_DATA::maxError, PID_DATA::maxSumError, PID_DATA::P_Factor, and PID_DATA::sumError.
Referenced by Init().
00037 { 00038 // Start values for PID controller 00039 pid->sumError = 0; 00040 pid->lastProcessValue = 0; 00041 // Tuning constants for PID loop 00042 pid->P_Factor = p_factor; 00043 pid->I_Factor = i_factor; 00044 pid->D_Factor = d_factor; 00045 // Limits to avoid overflow 00046 pid->maxError = MAX_INT / (pid->P_Factor + 1); 00047 pid->maxSumError = MAX_I_TERM / (pid->I_Factor + 1); 00048 }
void pid_Reset_Integrator | ( | pidData_t * | pid_st | ) |
Resets the integrator.
Calling this function will reset the integrator in the PID regulator.
Definition at line 112 of file pid.c.
References PID_DATA::sumError.
00113 { 00114 pid_st->sumError = 0; 00115 }