Trouble with using encoder and pid library together

Projects Programming
1

Hi, I'm a relative beginner with arduino. I've been working on a project that will use the PID library by Brett Beauregard. I have a rotary encoder and over the last few days, I've built a menu system that operates through clicking and rotating. However, now that I'm adding the PID library, I find when adding the initial declaration PID myPID(&input, &output, &setpoint, 1.0, 1.0, 1.0, DIRECT ); the rotary encoder stops working. Well at least the switch on the encoder does, I don't know if the rotary part of it works or not because that only functions after clicking the encoder. Has anyone else come across anything like this? My code below:

// Include necessary libraries
#define ENCODER_DO_NOT_USE_INTERRUPTS
#include <LiquidCrystal.h>


#include <Encoder.h>
#include <EEPROM.h>
//#include <Wire.h>
#include <PID_v1.h>

// Define LCD pins
const int rs = 5, en = 4, d4 = 3, d5 = 2, d6 = 1, d7 = 0;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

// Thermistor constants
#define RT0 200000  // Ω
#define B 4045      // K
#define R 100000    // Ω (resistor used in voltage divider)



// Encoder pins
#define ENCODER_CLK 6
#define ENCODER_DT 7
#define ENCODER_SW 8
Encoder encoder(ENCODER_DT, ENCODER_CLK);

// Relay output pins
#define RELAY_VALVE 9
#define RELAY_HEATER 10

// Analog input pins
#define TEMP_PIN A0
#define PRES_PIN A1

// Control parameters
const uint8_t NUM_VARIABLES = 7;
const uint8_t NUM_VARIABLESI = 3;
const uint8_t NUM_VARIABLESF = 7;
const char* variableNames[NUM_VARIABLESF] = { "Temp-ramp", "Temp-hold", "Time", "Pressure", "P" , "I", "D" };
const float variableminf[NUM_VARIABLESF] = {50.0, 50.0, 10.0, 0.1, 0.0, 0.0, 0.0 };
const float variablemaxf[NUM_VARIABLESF] = {220.0, 220.0, 240.0, 2.0, 50.0, 50.0, 50.0 };
const float variablefdefault[NUM_VARIABLESF] = {130.0, 145.0, 45, 0.5, 5.0, 1.0, 1.0 };
float variablesf[NUM_VARIABLESF];  // temps, time, Pressure, Proportional, Integeral, and Derivative terms



const int EEPROM_START_ADDR = 0;  // EEPROM starting address

// encoder variables
enum Mode { IDLE, NAVIGATE, EDIT };
Mode currentMode = IDLE;
long lastEncoderPosNormalized = 0;
int currentMenuItem = 0;
double tempEditValueFloat = 0.0;  
bool buttonState = HIGH;
bool lastButtonState = HIGH;
unsigned long lastDebounceTime = 0;
const unsigned long DEBOUNCE_DELAY = 25;
unsigned long pressStartTime = 0;
bool buttonPressedFlag = false;

// Program timer variables
unsigned long lastTempUpdate = 0;
unsigned long previousMillis = 0;
unsigned long programtimeseconds = 0;
unsigned long programtimeminutes = 0;
unsigned long programtimehours = 0;

// logic variables
bool started = false;  // flag for program started
bool steamvalveopen = false;

// variables for temperature measurement and pressure measurement
float RT, VR, ln, TX, T0, VRT;
float Pvoltage = 0.0;
float pressure = 0.0;
float maxpressure = 0.0;

double output, input, setpoint;
//PID* myPID;  // declare a pointer to a PID object
PID myPID(&input, &output, &setpoint, 1.0, 1.0, 1.0, DIRECT );
int WindowSize = 5000;
unsigned long windowStartTime;



void setup() {
  // Set pin modes
  pinMode(RELAY_HEATER, OUTPUT);
  pinMode(RELAY_VALVE, OUTPUT);
  pinMode(ENCODER_SW, INPUT_PULLUP);

  T0 = 25 + 273.15;  // Reference temp in Kelvin

  lcd.begin(16, 2);
  encoder.write(0);


  for (uint8_t i = 0; i < NUM_VARIABLESF; i++) {
  EEPROM.get(EEPROM_START_ADDR +  (i * sizeof(float)), variablesf[i]);
  if (isnan(variablesf[i]) || variablesf[i] < variableminf[i] || variablesf[i] > variablemaxf[i]) {
    variablesf[i] = variablefdefault[i];
  }
  }
  showIdle();
  
  windowStartTime = millis();

  //myPID = new PID(&input, &output, &setpoint, variablesf[4], variablesf[5], variablesf[6], DIRECT);
  //myPID.SetOutputLimits(0, WindowSize);
  //turn the PID on
  //myPID.SetMode(AUTOMATIC);
}

void loop() {
  // Temperature calculation
  VRT = (5.00 / 1023.00) * analogRead(A0);  // Voltage across thermistor
  VR = 5.00 - VRT;
  RT = VRT / (VR / R);                      // Resistance of thermistor
  ln = log(RT / RT0);                       // ln(RT/RT0)
  TX = (1 / ((ln / B) + (1 / T0))) - 273.15; // Temperature in Celsius

  // Pressure sensor conversion
  int sensorValue = analogRead(PRES_PIN);
  Pvoltage = sensorValue * (5.0 / 1023.0);
  pressure = 1.3953 * Pvoltage - 0.6977;  // Linear conversion formula
  
  
  // Program timer and heater/valve logic
  if (started && programtimeminutes < variablesf[2]) {  // program started and time running is less than the program length in minutes. set timer going
    unsigned long currentMillis = millis();
    if (currentMillis - previousMillis >= 1000) {
      previousMillis = currentMillis;
      programtimeseconds++;
      if (programtimeseconds > 59) {
        programtimeseconds = 0;
        programtimeminutes++;
      }
    }
    if (pressure > maxpressure) {  // Update maxpressure variable
      maxpressure = pressure;
    }
    
    if  ((maxpressure - pressure) > variablesf[3]) {  // turn on steam bleed valve to trap steam in vessel when pressure drops
      digitalWrite(RELAY_VALVE, HIGH);
      steamvalveopen = true;
    }
    input = TX;
    setpoint = variablesf[0];
    //myPID.Compute();
    if (millis() - windowStartTime > WindowSize){ 
      //time to shift the Relay Window
        windowStartTime += WindowSize;
      }
    if (output < millis() - windowStartTime) digitalWrite(RELAY_HEATER, HIGH);
    else digitalWrite(RELAY_HEATER, LOW);
    
    
    digitalWrite(RELAY_HEATER, HIGH);

  } else {  // program was cancelled or end of program was reached, turn heater off, open steam bleed valve, reset timer
    started = false;
    steamvalveopen = false;
    maxpressure = 0.0;
    digitalWrite(RELAY_VALVE, LOW);
    digitalWrite(RELAY_HEATER, LOW);
    programtimeseconds = 0;
    programtimeminutes = 0;
    programtimehours = 0;
  }

  readButton();
  handleEncoder();

  if (currentMode == IDLE && (millis() - lastTempUpdate > 1000)) {  //Update display every second
    lastTempUpdate = millis();
    updateIdleDisplay();
  }
}

// Read encoder pushbutton with debounce
void readButton() {
  int reading = digitalRead(ENCODER_SW);
  if (reading != lastButtonState) lastDebounceTime = millis();

  if ((millis() - lastDebounceTime) > DEBOUNCE_DELAY) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == LOW) {
        pressStartTime = millis();
        buttonPressedFlag = false;
      } else {
        unsigned long pressDuration = millis() - pressStartTime;
        if (pressDuration >= 500) handleLongPress();
        else if (!buttonPressedFlag) handleShortPress();
      }
    }
  }
  lastButtonState = reading;
}

// Handle short press (edit variable or enter menu)
void handleShortPress() {
  if (currentMode == IDLE) {
    currentMode = NAVIGATE;
    currentMenuItem = 0;
    encoder.write(currentMenuItem * 4);
    lastEncoderPosNormalized = currentMenuItem;
    showNavigate();
  } else if (currentMode == NAVIGATE) {
  currentMode = EDIT;
  tempEditValueFloat = variablesf[currentMenuItem];

  if (currentMenuItem < NUM_VARIABLESI) {
    // First 3 variables: step size = 1
    encoder.write((int)(tempEditValueFloat) * 4);
    lastEncoderPosNormalized = (int)(tempEditValueFloat);
  } else {
    // Remaining variables: step size = 0.1
    encoder.write((int)(tempEditValueFloat * 10) * 4);
    lastEncoderPosNormalized = (int)(tempEditValueFloat * 10);
  }

    showEdit();
  } else if (currentMode == EDIT) {

    variablesf[currentMenuItem] = tempEditValueFloat;
    EEPROM.put(EEPROM_START_ADDR + currentMenuItem * sizeof(float), tempEditValueFloat);

    lcd.clear();
    lcd.print("Saved ");
    lcd.print(variableNames[currentMenuItem]);
    delay(800);

    currentMode = NAVIGATE;
    encoder.write(currentMenuItem * 4);
    lastEncoderPosNormalized = currentMenuItem;
    showNavigate();
  }
}

// Handle long press (cancel edit or toggle state)
void handleLongPress() {
  if (currentMode == EDIT) {
    currentMode = NAVIGATE;
    encoder.write(currentMenuItem * 4);
    lastEncoderPosNormalized = currentMenuItem;
    showNavigate();
  } else if (currentMode == NAVIGATE) {
    currentMode = IDLE;
    showIdle();
  } else if (currentMode == IDLE) {
    started = !started;
  }
}

// Handle encoder rotation
void handleEncoder() {
  long rawPos = encoder.read();
  long expectedRawPos = lastEncoderPosNormalized * 4;
  long deltaRaw = rawPos - expectedRawPos;

  // Filter large unexpected jumps (e.g., > 8 counts)
  if (abs(deltaRaw) > 8) {
    // Resynchronize encoder position to last known stable value
    encoder.write(expectedRawPos);
    return;
  }

  // Only process when a full step (4 counts) is detected
  if (deltaRaw >= 4 || deltaRaw <= -4) {
    // Determine direction: positive or negative step(s)
    int steps = deltaRaw / 4;  // Number of steps moved (can be >1 or < -1)

    if (currentMode == NAVIGATE) {
      int newMenuItem = currentMenuItem + steps;

      // Clamp newMenuItem within valid menu range
      if (newMenuItem < 0) newMenuItem = 0;
      if (newMenuItem >= NUM_VARIABLES) newMenuItem = NUM_VARIABLES - 1;

      if (newMenuItem != currentMenuItem) {
        currentMenuItem = newMenuItem;
        lastEncoderPosNormalized = currentMenuItem;
        encoder.write(currentMenuItem * 4);
        showNavigate();
      } else {
        // If no menu change, just resync encoder write
        encoder.write(lastEncoderPosNormalized * 4);
      }
    }else if (currentMode == EDIT) {
      int pos = lastEncoderPosNormalized + steps;

      if (currentMenuItem < NUM_VARIABLESI) {
        // Whole number steps
        int minPos = (int)variableminf[currentMenuItem];
        int maxPos = (int)variablemaxf[currentMenuItem];

        if (pos < minPos) pos = minPos;
        if (pos > maxPos) pos = maxPos;

        if (pos != lastEncoderPosNormalized) {
          lastEncoderPosNormalized = pos;
          tempEditValueFloat = (float)pos;
          encoder.write(pos * 4);
          showEdit();
        } else {
          encoder.write(lastEncoderPosNormalized * 4);
        }

      } else {
        // Decimal steps of 0.1
        int minPos = (int)(variableminf[currentMenuItem] * 10);
        int maxPos = (int)(variablemaxf[currentMenuItem] * 10);

        if (pos < minPos) pos = minPos;
        if (pos > maxPos) pos = maxPos;

        if (pos != lastEncoderPosNormalized) {
          lastEncoderPosNormalized = pos;
          tempEditValueFloat = pos / 10.0;
          encoder.write(pos * 4);
          showEdit();
        } else {
          encoder.write(lastEncoderPosNormalized * 4);
        }
      }
    }
  }
}

// Display idle screen with temperature and pressure
void showIdle() {
  lcd.clear();
  updateIdleDisplay();
}

// Update idle display every second
void updateIdleDisplay() {
  
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(TX, 1);
  lcd.print(" ");
  lcd.write(byte(223));  // Degree symbol
  lcd.print("C");

  char timeBuffer[6];
  sprintf(timeBuffer, "%3lu:%02lu", programtimeminutes, programtimeseconds);
  lcd.setCursor(10, 0);
  lcd.print(timeBuffer);

  lcd.setCursor(0, 1);
  lcd.print(pressure, 2);
  lcd.print(" Bar ");
  lcd.print(maxpressure, 2);
  
}

// Show variable navigation screen
void showNavigate() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(variableNames[currentMenuItem]);
  lcd.print(" = ");

  lcd.print(variablesf[currentMenuItem], 1);

  lcd.setCursor(0, 1);
  lcd.print("Click to edit");
}

// Show variable editing screen
void showEdit() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Edit ");
  lcd.print(variableNames[currentMenuItem]);
  lcd.setCursor(0, 1);
  lcd.print("Value: ");
  lcd.print(tempEditValueFloat, 1);

}
2

You say you are a beginner but you choose to write your own switch handling code rather than using an established library. I will make a small wager I know where the bug(s) are.

I see you using the encoder as an OUTPUT device. I had no idea you could do that and no idea what will happen.

I had coded up a menu system using an encoder for a project earlier this year, but I ended up not using a menu at all. The code was much simpler and certainly no writing to it.

I will follow this thread with interest, maybe this old dog (83) can still learn a new trick.

3

Thank you for replying. Could you suggest an established library? To be very frank, I didn't write most of the code, ChatGPT played a heavy part in it. I'd love to be able to make the code simpler and more robust.

4

I think you're mistaken, it's not set up as an Output device. The two Pinmodes above the pinmode for the encoder switch are for a different part of the code and are nothing to do with the encoder

5

That isn't an encoder?

6

Here are the libraries I used. I think one is used by the other. I had a rotary encoder where I could read number of clicks CW or CCW, long press, click, double click.

#include <EncoderButton.h>

#include <Button2.h>

7

Button2.h will allow you to get rid of a lot of debounce code you have manually inserted in your sketch, now it will be simply ifPressed

8

Yes, apparently it’s writing to the internal position counter maintained by the Encoder library.

I really am grateful for any help on this. I'll look at the libraries you suggested. Thank you.

9

I added an lcd.print to the readButton() function.

With 'PID myPID(&input, &output, &setpoint, 1.0, 1.0, 1.0, DIRECT );' commented out, it prints 1 when the button isn't clicked, and 0 when it's clicked (seems correct.) If I uncomment the PID code, it produces the number 42949552. I can't work out why!

Edit: If I comment out handleShortPress() and handleLongPress() it produced the 1 and 0 again.

Code below:

void readButton() {
  int reading = digitalRead(ENCODER_SW);
  
  lcd.setCursor(8, 0);
  lcd.print(int(reading));  
  if (reading != lastButtonState) lastDebounceTime = millis();

  if ((millis() - lastDebounceTime) > DEBOUNCE_DELAY) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == LOW) {
        pressStartTime = millis();
        buttonPressedFlag = false;
      } else {
        unsigned long pressDuration = millis() - pressStartTime;
        if (pressDuration >= 500) {
          handleLongPress();

        } else if (!buttonPressedFlag) {
          handleShortPress();
      
          buttonPressedFlag = true;  // Prevent repeated short press handling
        }
      }
    }
  }
  lastButtonState = reading;
}
10

It will be interesting to see what happens when you make use of the Button2 library.

11

This afternoon I looked at the code again, it seems the sprintf functions I was using for the lcd display was creating the problem. removing those has solved the problem. Btw, I've converted the code to use the ButtonEncoder library and it is a lot cleaner and simpler than what I originally had. However, it still didn't work properly when I added the PID library added and only after removing those sprintf functions did it start working. Thanks for the suggestion to use a library!

12

Your sprintf() statement is likely overflowing the timeBuffer array. Why did you only reserve 6 bytes?