Cédric Sylvestre
PIDHeater82
Dependencies: PID mbed millis ttmath
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PIDHeater
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FRDM-K64F Code Share
Revision 3:00a491d8ed0c, committed 2017-06-23
- 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 |
--- 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;
}
-
+
--- /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