Diff: PID_simpler.cpp

Revision:

0:febde40ccef5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PID_simpler.cpp	Mon Dec 14 14:23:04 2020 +0000
@@ -0,0 +1,76 @@
+#include "mbed.h"
+#include "millis.h"
+/*working variables*/
+
+#define threshold 0.003 // 1/330
+
+AnalogIn temperature(p20);
+PwmOut fanControl(p21);
+//static BufferedSerial pc(USBTX, USBRX);
+
+Ticker temperatureTicker;
+
+int readTemperatureFlag=0;
+unsigned long lastTime;
+double Input, Output, Setpoint;
+double errSum, lastErr;
+double kp, ki, kd;
+void Compute()
+{
+   /*How long since we last calculated*/
+   unsigned long now = millis();
+   double timeChange = (double)(now - lastTime);
+  
+   /*Compute all the working error variables*/
+   double error = Setpoint - Input;
+   errSum += (error * timeChange);
+   double dErr = (error - lastErr) / timeChange;
+  
+   /*Compute PID Output*/
+   Output = kp * error + ki * errSum + kd * dErr;
+  
+   /*Remember some variables for next time*/
+   lastErr = error;
+   lastTime = now;
+}
+  
+void SetTunings(double Kp, double Ki, double Kd)
+{
+   kp = Kp;
+   ki = Ki;
+   kd = Kd;
+}
+void tickerFlagOn()
+{
+    //led2 = !led2;
+    readTemperatureFlag=1;
+}
+
+int main()
+{
+    float oldTemperature = temperature.read();
+    float newTemperature= oldTemperature;
+    temperatureTicker.attach(&tickerFlagOn, 0.200); // the address of the function to be attached (tickerFlagOn) and the interval (0.2 seconds)
+    
+    while (1)
+    {
+        if (readTemperatureFlag)
+        {
+            readTemperatureFlag=0;
+            newTemperature = temperature.read();
+            if ((newTemperature < (oldTemperature-threshold)) || (newTemperature > (oldTemperature+threshold)))
+            {
+                oldTemperature = newTemperature; // These are for the threshold
+                printf("AnalogIn=%f, Temperature= %.1f degrees\n\r", oldTemperature, 3.3*oldTemperature*100);
+            }
+        }
+    
+    Input=oldTemperature;
+    Setpoint= 0.0757575757575758;
+    SetTunings(1, 0, 0);
+    Compute();
+    fanControl.write(Output);
+    printf("fanSpeed=%f \n \r", Output); 
+    wait(1);   
+    }
+}