PIDHeater82

Dependencies:   PID mbed millis ttmath

Fork of PIDHeater by FRDM-K64F Code Share

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API Documentation at this revision

Comitter:
Cedricbts
Date:
Fri Jun 23 14:53:24 2017 +0000
Parent:
2:6e731a17523c
Commit message:
PIDHeater82

Changed in this revision

main.cpp Show annotated file Show diff for this revision Revisions of this file
ttmath.lib Show annotated file Show diff for this revision Revisions of this file
diff -r 6e731a17523c -r 00a491d8ed0c main.cpp
--- a/main.cpp	Sun Feb 07 19:08:57 2016 +0000
+++ b/main.cpp	Fri Jun 23 14:53:24 2017 +0000
@@ -1,39 +1,16 @@
-/** A demo application to show how to mangage and control a heater element 
- * through a PID loop using a Thermistor input and PWM output
- * for the @NXP (@freescale) FRDM-K64F demo board.
- *
- * This particular example drives the heater element for a 3d Printer Extruder.
- *
- * For more information on PID control check out Brett Beauregard's Arduino PID library:
- *
- *  https://github.com/br3ttb/Arduino-PID-Library
- *
- * The wikipedia article on PID controllers is a good place to start on
- * understanding how they work:
- *
- *  http://en.wikipedia.org/wiki/PID_controller
- *
- * The Thermistor value to Temerature routine uses the Steinhart-Hart equation.
- This is a Thermistor to Temerature conversion demo 
-
-Much thanks to @Adafruit for this tutorial:
-https://learn.adafruit.com/thermistor/using-a-thermistor
-
-The 100K Thermistor is configured with a 4.7k series resistor 
-tied to vcc (3.3v)  like this:
-
+/*
     +3.3v
       |
       \
-      /  4.7k series resistor
+      /  10k Résistance série
       \
       /
       |
-      .-----------O To Anlog pin on FRDM board
+      .-----------O Vers Anolog 0 de la carte
       |
       \
       /
-  Thermistor  100k Nominal
+  Thermistance  10k Nominal
       \
       /
       |
@@ -54,25 +31,25 @@
 Ticker PrintTicker;                     // Send process results to Console once per second       
 Ticker ticker;                          // Set up the millis() ticker.
                                        
-#define  DEFAULT_Kp 1
-#define  DEFAULT_Ki 0.002
-#define  DEFAULT_Kd 20
+#define  DEFAULT_Kp 100
+#define  DEFAULT_Ki 0
+#define  DEFAULT_Kd 0
 
 #define AUTOMATIC 1
 #define MANUAL    0
 #define DIRECT  0
 #define REVERSE  1
-#define thermistor A3                       // FRDM-K64F Analog input pin A3   - Adjust to your particular board
-#define driver PTC3                         // FRDM-K64F PWM output pin PTC3   - Adjust to your particular board
-
-AnalogIn Thermistor(thermistor);            // Read temperature value from thermistor on A3
-PwmOut Driver(driver);                      // PWM drive FET heater on PTC3  values are 0-1.0 
+#define thermistor A0                       // Analog input pin A0 
+#define driver PB_3                         // PWM output pin PB_3
+#define PERIOD 2.0
+AnalogIn Thermistor(thermistor);            // Read temperature value from thermistor on A0
+PwmOut Driver(PB_3);                      // PWM drive values are 0-1.0 
                                             // For 0-100% 
-             
+float temp;             
 float Input, Output, Setpoint; 
 PID controller(&Input, &Output, &Setpoint, DEFAULT_Kp , DEFAULT_Ki , DEFAULT_Kd , DIRECT);
 
-#define RATE 1.0                            // Print rate  Once per second
+#define RATE 2.0                            // Print rate  once every two seconds
   
 void PrintValues() {                        // Routine to print out results to console
     pc.printf("Input      Output     Setpoint   Kp        Ki        Kd        time\r\n");
@@ -86,14 +63,13 @@
  
   startMillis();                            // Initialize timer.
  
-  pc.baud(115200);    
-  pc.printf("\r\nThermistor PID Test - Build " __DATE__ " " __TIME__ "\r\n");
+  pc.baud(9600);    
+  //pc.printf("\r\nThermistor PID Test - Build " __DATE__ " " __TIME__ "\r\n");
   
-  PrintTicker.attach(&PrintValues,RATE);    // Start PID process running at 100ms rate.
-
-  Setpoint = 80;                            // Set target temperature in degrees Celcius.
+  PrintTicker.attach(&PrintValues,RATE);    // Start PID process running at 2s rate.
+  controller.SetSampleTime(2000);
+  Setpoint = 24;                            // Set target temperature in degrees Celcius.
   controller.SetMode(AUTOMATIC);            // Turn PID controller on.
-  
 
   while(1){
    
@@ -102,50 +78,20 @@
      controller.Compute();                  // Process PID loop. 
 
      Driver = Output/1000;                  // Sent PWM value scaled 0 - 1.0 as mbed requires 
-
+    
   }
  
 }
 
 
-// This is the workhorse routine that calculates the temperature
-// using the Steinhart-Hart equation for thermistors
-// https://en.wikipedia.org/wiki/Steinhart%E2%80%93Hart_equation
-
 float getTemperature() {
-#define THERMISTORNOMINAL 100000      // 100k 
-// temp. for nominal resistance (almost always 25 C)
-#define TEMPERATURENOMINAL 25   
-// The beta coefficient of the thermistor (usually 3000-4000)
-#define BCOEFFICIENT 3950
-// the value of the 'other' resistor
-#define SERIESRESISTOR 4700    
-
-// This is the workhorse routine that calculates the temperature
-// using the Steinhart-Hart equation for thermistors
-// https://en.wikipedia.org/wiki/Steinhart%E2%80%93Hart_equation
-
-    float temperature, resistance;
-    float steinhart;
-    int a;
-    
-    a = Thermistor.read_u16();       // Read 16bit Analog value
-//    pc.printf("Raw Analog Value for Thermistor = %d\r\n",a);
-  
-    /* Calculate the resistance of the thermistor from analog votage read. */
-    resistance = (float) SERIESRESISTOR / ((65536.0 / a) - 1);
-//    pc.printf("Resistance for Thermistor = %f\r\n",resistance);
-   
-    steinhart = resistance / THERMISTORNOMINAL;         // (R/Ro)
-    steinhart = log(steinhart);                         // ln(R/Ro)
-    steinhart /= BCOEFFICIENT;                          // 1/B * ln(R/Ro)
-    steinhart += 1.0 / (TEMPERATURENOMINAL + 273.15);   // + (1/To)
-    steinhart = 1.0 / steinhart;                        // Invert
-    temperature = steinhart - 273.15;                   // convert to C
-
-//    pc.printf("Extruder Temperature is %f\r\n", temperature);
+float h = Thermistor.read_u16();
+    h = (h/65536)*3.3;                      //Conversion Bit to Voltage
+    pc.printf("voltage %f\r\n", h);
+    temp = -30.705*h+91.788;                //Converson Voltage to °C
+    pc.printf("temp = %f\r\n",temp);
  
-    return temperature;    
+    return temp;    
 
 }
- 
+
diff -r 6e731a17523c -r 00a491d8ed0c ttmath.lib
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ttmath.lib	Fri Jun 23 14:53:24 2017 +0000
@@ -0,0 +1,1 @@
+http://developer.mbed.org/users/stevep/code/ttmath/#04a9f72bbca7