FRDM-K64F Code Share
Extruder/Heated bed PID control for the FRDM-K64F
Revision 2:6e731a17523c, committed 2016-02-07
- Comitter:
- unix_guru
- Date:
- Sun Feb 07 19:08:57 2016 +0000
- Parent:
- 1:b852d582ad0e
- Commit message:
- FRDM-K64F - First version of PID heater control demo to manage temperature on a 3d printer extruder.
Changed in this revision
diff -r b852d582ad0e -r 6e731a17523c PID.lib --- a/PID.lib Wed Jan 27 21:32:34 2016 +0000 +++ b/PID.lib Sun Feb 07 19:08:57 2016 +0000 @@ -1,1 +1,1 @@ -https://developer.mbed.org/teams/FRDM-K64F-Code-Share/code/PID/#55bf0f813bb4 +https://developer.mbed.org/teams/FRDM-K64F-Code-Share/code/PID/#316f974b7f98
diff -r b852d582ad0e -r 6e731a17523c PIDHeater.cpp
--- a/PIDHeater.cpp Wed Jan 27 21:32:34 2016 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,75 +0,0 @@
-#include "PIDHeater.h"
-
-PID controller(DEFAULT_Kp , DEFAULT_Ki , DEFAULT_Kd , 0.1); // Initialize PID controller -- Kc, Ti, Td, interval
-
-
-PIDHeater::PIDHeater(PinName sensorPin, PinName pwmoutPin): thermistor(sensorPin), driver(pwmoutPin) {
-
- heaterOn = false;
- controller.setInputLimits(0, 250); // MIN/MAX Temperature values
- controller.setOutputLimits(0.0, 1.0); // Pwm output from 0.0 to 1.0
-// controller.setMode(AUTO);
- controller.setSetPoint(22); // Set initial Temperature to 22 degrees celcius
- }
-
-void PIDHeater::configureRange(float minTemperature, float maxTemperature) {
- if (minTemperature < maxTemperature) {
- minTemp = minTemperature;
- maxTemp = maxTemperature;
- controller.setInputLimits(minTemperature, maxTemperature); // MIN/MAX Temperature values
- }
-}
-
-float PIDHeater::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
-
- return temperature;
-
-}
-
-bool PIDHeater::isHeaterOn() {
- return heaterOn;
-}
-
-void PIDHeater::run() {
- getTemperature();
- driver = controller.compute();
-}
-
-
-void PIDHeater::setTemperature(float temp) {
- if (temp >= minTemp && temp <= maxTemp) {
- desiredTemp = temp;
- controller.setSetPoint(desiredTemp); // Set desired temperature in celcius
- }
-}
-
-
\ No newline at end of file
diff -r b852d582ad0e -r 6e731a17523c PIDHeater.h
--- a/PIDHeater.h Wed Jan 27 21:32:34 2016 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,43 +0,0 @@
-#ifndef PID_HEATER_H
-#define PID_HEATER_H
-
-#include "mbed.h"
-
-#include "PID.h"
-// These values were borrowed from Marlin Firmware defaults
-#define DEFAULT_Kp 17.52
-#define DEFAULT_Ki 0.62
-#define DEFAULT_Kd 123.43
-
-
-/** A simple class for temperature control of a heater element using PID
- * a heater driven via PWM digital output and one analog temperature sensor.
- *
- * Author(s): Michael Ball unix_guru@hotmail.com
- *
- */
-class PIDHeater{
- public:
- /** Constructor receives pin names of the temperature sensor and
- * the DigitalOut pin to which the heater driver is connected. */
- PIDHeater(PinName sensorPin, PinName digitalOutPin);
- /** Set the temperature range of the sensor. */
- void configureRange(float minTemperature, float maxTemperature);
- /** Read the current room temperature from the sensor. */
- float getTemperature();
- /** Test if the heater in turned ON. */
- bool isHeaterOn();
- /** Set the desired room temperature. */
- void setTemperature(float temp);
- /** Attach run process to a timer */
- void run();
-
- private:
- AnalogIn thermistor;
- DigitalOut driver;
- Ticker ticker;
- bool heaterOn;
- float currentTemp, desiredTemp, minTemp, maxTemp, hysteresis, pwmValue;
-};
-
-#endif // HEATER_H
\ No newline at end of file
diff -r b852d582ad0e -r 6e731a17523c main.cpp
--- a/main.cpp Wed Jan 27 21:32:34 2016 +0000
+++ b/main.cpp Sun Feb 07 19:08:57 2016 +0000
@@ -1,39 +1,151 @@
/** 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 more information on PID control
+ * 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
+ \
+ /
+ |
+ .-----------O To Anlog pin on FRDM board
+ |
+ \
+ /
+ Thermistor 100k Nominal
+ \
+ /
+ |
+ ---
+ GND
*
* Author(s): Michael Ball unix_guru@hotmail.com
*
*/
#include "mbed.h"
-
-#include "PIDHeater.h" // PIDHeater simply takes two variables
- // The Thermistor input and the Heater output.
- //
+#include "millis.h"
+#include "PID.h"
+
+float getTemperature();
+
Serial pc(USBTX, USBRX);
-Ticker ticker;
+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 RATE 0.1 // Check temp every 100ms
-PIDHeater extruder(A3, PTC3); // Thermistor on A3 heater on PTC3
+#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
-void run_PID_loop() { // Periodically test temperature and set output
- extruder.run();
+AnalogIn Thermistor(thermistor); // Read temperature value from thermistor on A3
+PwmOut Driver(driver); // PWM drive FET heater on PTC3 values are 0-1.0
+ // For 0-100%
+
+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
+
+void PrintValues() { // Routine to print out results to console
+ pc.printf("Input Output Setpoint Kp Ki Kd time\r\n");
+ pc.printf("%f, %f, %f, %f, %f, %f, %d \r\n",
+ Input, Output, Setpoint, controller.GetKp() , controller.GetKi() , controller.GetKd() , millis() );
+
}
+
int main(){
- extruder.configureRange(0,250); // Set MIN/MAX temperature in degrees Celcius.
- extruder.setTemperature(25); // Set target temperature to 25 degrees Celcius.
+ startMillis(); // Initialize timer.
+
+ pc.baud(115200);
+ pc.printf("\r\nThermistor PID Test - Build " __DATE__ " " __TIME__ "\r\n");
- ticker.attach(&run_PID_loop,RATE); // Start PID process running at 100ms rate.
+ PrintTicker.attach(&PrintValues,RATE); // Start PID process running at 100ms rate.
+
+ Setpoint = 80; // Set target temperature in degrees Celcius.
+ controller.SetMode(AUTOMATIC); // Turn PID controller on.
+
while(1){
- pc.printf("Extruder Temperature is %f\r\n", extruder.getTemperature());
-
- wait(1);
+ Input = getTemperature(); // Actual temperature in Degrees Celcius
+
+ controller.Compute(); // Process PID loop.
+
+ Driver = Output/1000; // Sent PWM value scaled 0 - 1.0 as mbed requires
}
-}
\ No newline at end of file
+}
+
+
+// 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);
+
+ return temperature;
+
+}
+
diff -r b852d582ad0e -r 6e731a17523c millis.lib --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/millis.lib Sun Feb 07 19:08:57 2016 +0000 @@ -0,0 +1,1 @@ +http://developer.mbed.org/teams/DFRobot/code/millis/#736e6cc31bcd