Diff: PID/PID.cpp

Revision:

54:c14c3bc48b8a

Parent:

51:1e6334b993a3

Child:

55:ee5257fb73df

diff -r 3573a1c8b71a -r c14c3bc48b8a PID/PID.cpp
--- a/PID/PID.cpp	Fri Oct 09 11:44:05 2015 +0000
+++ b/PID/PID.cpp	Fri Oct 09 12:08:35 2015 +0000
@@ -3,8 +3,9 @@
 #include "PID.h"
 #include "mbed.h"
 
-Timer t;  // create Timer object t
-t.start(); // start the timer 
+// PID is called with interrupt caller, so no need to keep track of time since dT is constant
+//Timer t;  // create Timer object t
+//t.start(); // start the timer 
 
 
 PID::PID(float* Input, float* Output, float* Setpoint, float Kp, float Ki, float Kd){
@@ -18,20 +19,20 @@
 	SampleTime = 0.1; 
 
 	PID::SetTunings(Kp, Ki, Kd);
-	prevTime = t.read();
+//	prevTime = t.read();
 }
 
-bool PID::compute(){
+bool PID::Compute(){
 	if(!inAuto) return false;
 
-	curTime = t.read()  // read time in seconds
-	timeChange = curTime - prevTime;
+//	curTime = t.read()  // read time in seconds (no need since called by interrupt)
+//	timeChange = curTime - prevTime;
 
 	// calculate using sample time frequency (regular intervals)
 	// no more need to modify derivative/int sicne sample time is constant
-	if(timeChange <=SampleTime){ 
+//	if(timeChange <=SampleTime){ 
 		float input = *myInput;
-		error = Setpoint - input;  // get error for proportional
+		error = *mySetpoint - input;  // get error for proportional
 		errSum += error;  // Error for integral
 		// check for integrator windup
 		if(errSum> outMax) errSum=outMax;
@@ -46,13 +47,13 @@
 		else if(output<outMin) output=outMin;
 		*myOutput = output;
 		lastErr = error;
-		prevTime = curTime;
+//		prevTime = curTime;
 		return true;
-	}
-	else return false;
+//	}
+//	else return false;
 }
 
-void PID::SetTunigns(float Kp, float Ki, float Kd)
+void PID::SetTunings(float Kp, float Ki, float Kd)
 {
 	Kp = Kp;
 	Ki = Ki * SampleTime; // change PID parameters according to sample time
@@ -75,11 +76,13 @@
 	outMin = min;
 	outMax = max;
 
-	if(Output > outMax) Output = outMax;
-	else if(Output < outMin) Output = outMin;
-
-	if(ITerm> outMax) ITerm= outMax;
-	else if(ITerm< outMin) ITerm= outMin;
+	if(inAuto){
+		if(*myOutput > outMax) *myOutput = outMax;
+		else if(*myOutput < outMin) *myOutput = outMin;
+	
+		if(errSum> outMax) errSum= outMax;
+		else if(errSum< outMin) errSum= outMin;
+	}
 }
 
 void PID::SetMode(int Mode){
@@ -92,8 +95,9 @@
 }
 
 void PID::Initialize(){
-	lastInput = Input;
-	errSum = Output;
+	lastInput = *myInput;
+	errSum = *myOutput;
+	lastErr = 0;
 	if(errSum> outMax) errSum=outMax;
 	else if(errSum<outMin) errSum=outMin;
 }
\ No newline at end of file