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David R Forrest
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Add examples/PID_simulated_heater_disp with LCD
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‎examples/PID_simulated_heater_disp/PID_simulated_heater_disp.ino

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/********************************************************
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PID Basic simulated heater Example
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Reading simulated analog input 0 to control analog PWM output 3
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********************************************************/
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// This simulates a 20W heater block driven by the PID
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// Vary the setpoint with the Pot, and watch the heater drive the temperature up
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//
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// Simulation at https://wokwi.com/projects/359088752027305985
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//
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// Based on
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// Wokwi https://wokwi.com/projects/357374218559137793
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// Wokwi https://wokwi.com/projects/356437164264235009
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#include "PID_v1.h" // https://github.com/br3ttb/Arduino-PID-Library
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// local copy of .h and .cpp are tweaked to expose the integral per
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// https://github.com/br3ttb/Arduino-PID-Library/pull/133
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#define USE_HACK // access the PID.outputSum variable
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//Define Variables we'll be connecting to
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double Setpoint, Input, Output;
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//Specify the links and initial tuning parameters
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//double Kp = 20, Ki = .01, Kd = 10; // works reasonably with sim heater block fo 220deg
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double Kp = 25.5, Ki = 0.1, Kd = 0; // +/-10°proportional band
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//double Kp = 255, Ki = 0.05, Kd = 0; // works reasonably with sim heater block
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//double Kp = 255, Ki = .0, Kd = 0; // +/-1° proportional band works reasonably with sim heater block
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//double Kp = 10000, Ki = 0.0, Kd = 0.0; // bang-bang
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//double Kp = 2, Ki = 0.0, Kd = 0.0; // P-only
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//double Kp = 2, Ki = 5, Kd = 1; // commonly used defaults
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PID myPID(&Input, &Output, &Setpoint, Kp, Ki, Kd, P_ON_E, DIRECT);
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const int PWM_PIN = 3; // UNO PWM pin for Output
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const int INPUT_PIN = -1; // Analog pin for Input (set <0 for simulation)
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const int SETPOINT_PIN = A1; // Analog pin for Setpoint Potentiometer
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const int AUTOMATIC_PIN = 8; // Pin for controlling manual/auto mode, NO
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const int OVERRIDE_PIN = 12; // Pin for integral override, NO
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const int PLUS_PIN = 4; // Pin for integral override, NO
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const int MINUS_PIN = 7; // Pin for integral override, NO
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const int LCD_SDA_PIN = A4; // Used by LiquidCrystal_I2C
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const int LCD_SCL_PIN = A5; // Used by LiquidCrystal_I2C
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#include <LiquidCrystal_I2C.h> // https://github.com/johnrickman/LiquidCrystal_I2C
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#define I2C_ADDR 0x27
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#define LCD_COLUMNS 20
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#define LCD_LINES 4
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LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES); // uses SDA=A4,SCL=A5 on Uno
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void setup()
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{
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Serial.begin(115200);
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Serial.println(__FILE__);
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myPID.SetOutputLimits(0, 255); // -4 for
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pinMode(OVERRIDE_PIN, INPUT_PULLUP);
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pinMode(AUTOMATIC_PIN, INPUT_PULLUP);
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pinMode(MINUS_PIN, INPUT_PULLUP);
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pinMode(PLUS_PIN, INPUT_PULLUP);
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Setpoint = 0;
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//turn the PID on
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myPID.SetMode(AUTOMATIC);
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if(INPUT_PIN>0){
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Input = analogRead(INPUT_PIN);
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}else{
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Input = simPlant(0.0,1.0); // simulate heating
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}
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lcd.init();
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lcd.backlight();
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Serial.println("Setpoint Input Output Integral");
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}
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void loop()
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{
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// gather Input from INPUT_PIN or simulated block
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float heaterWatts = Output * 20.0 / 255; // 20W heater
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if (INPUT_PIN > 0 ) {
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Input = analogRead(INPUT_PIN);
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} else {
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float blockTemp = simPlant(heaterWatts,Output>0?1.0:1-Output); // simulate heating
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Input = blockTemp; // read input from simulated heater block
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}
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if (myPID.Compute())
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{
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//Output = (int)Output; // Recognize that the output as used is integer
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analogWrite(PWM_PIN, Output);
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}
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Setpoint = analogRead(SETPOINT_PIN) / 4; // Read setpoint from potentiometer
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if(digitalRead(OVERRIDE_PIN)==LOW) mySetIntegral(&myPID,0); // integral override
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if(digitalRead(AUTOMATIC_PIN)==HIGH != myPID.GetMode()==AUTOMATIC){
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myPID.SetMode(digitalRead(AUTOMATIC_PIN)==HIGH ? AUTOMATIC :MANUAL);
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}
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static uint32_t lastButton = 0;
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if(myPID.GetMode()==MANUAL && millis() - lastButton > 250){
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if(digitalRead(PLUS_PIN)==LOW){
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Output += 1;
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lastButton = millis();
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}
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if(digitalRead(MINUS_PIN)==LOW){
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Output -= 1;
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lastButton = millis();
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}
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}
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report();
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reportLCD();
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}
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void report(void)
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{
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static uint32_t last = 0;
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const int interval = 250;
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if (millis() - last > interval) {
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last += interval;
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// Serial.print(millis()/1000.0);
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Serial.print("SP:");Serial.print(Setpoint);
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Serial.print(" PV:");
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Serial.print(Input);
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Serial.print(" CV:");
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Serial.print(Output);
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Serial.print(" Int:");
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#if defined(USE_HACK)
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Serial.print(myPID.outputSum);
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#endif
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Serial.print(' ');
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Serial.println();
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}
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}
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void reportLCD(void)
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{
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static uint32_t last = 0;
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const int interval = 250;
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if (millis() - last > interval) {
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last += interval;
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// Serial.print(millis()/1000.0);
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// lcd.clear();
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lcd.setCursor(0,0);
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lcd.print("PV:");
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lcd.print(Input,3);
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lcd.print(" CV:");
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lcd.print(Output,3);
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lcd.print(" ");
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lcd.setCursor(0,1);
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lcd.print("SP:");
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lcd.print(Setpoint,3);
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lcd.print(myPID.GetMode()==AUTOMATIC? " Automatic ":" Manual ");
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lcd.print(" ");
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lcd.setCursor(0,3);
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lcd.print("Int:");
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#if defined(USE_HACK)
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lcd.print(myPID.outputSum,4);
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#endif
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lcd.print(' ');
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lcd.println();
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}
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}
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float simPlant(float Q,float hfactor) { // heat input in W (or J/s)
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// simulate a 1x1x2cm aluminum block with a heater and passive ambient cooling
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// float C = 237; // W/mK thermal conduction coefficient for Al
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float h = 5 *hfactor ; // W/m2K thermal convection coefficient for Al passive
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float Cps = 0.89; // J/g°C
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float area = 1e-4; // m2 area for convection
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float mass = 10 ; // g
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float Tamb = 25; // °C
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static float T = Tamb; // °C
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static uint32_t last = 0;
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uint32_t interval = 100; // ms
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if (millis() - last >= interval) {
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last += interval;
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// 0-dimensional heat transfer
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T = T + Q * interval / 1000 / mass / Cps - (T - Tamb) * area * h;
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}
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return T;
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}
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void mySetIntegral(PID * ptrPID,double value ){
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ptrPID->SetMode(MANUAL);
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Output = value;
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ptrPID->SetMode(AUTOMATIC);
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}
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‎library.properties

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name=PID_v1_bc
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version=1.2.3
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version=1.2.4
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author=David Forrest
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maintainer=David Forrest
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sentence=PID controller based on PID_v1 with back-calculation anti-windup

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