How to override "waitforkey" function

Projects Programming
1

Hello everyone,

I am new to this forum and have a few question hoping that you guys can help. My project consists of Arduino, keypad, LCD screen, PWM output, and a rotary encoder. I got everything working, and I have merged all the code together except the rotary encoder that does not work properly which I suspect that "waitforkey" function hold up the whole process, and it results in the encoder only run once after I input the value. I want it to run in parallel to the main code. Therefore, I am trying to find a way to override "waitforkey" function. Any help would be appreciated. Thank you in advance.

Main code:

#include <Keypad.h>
#include <Wire.h>  
#include <LiquidCrystal_I2C.h>


LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
char key;
char PWM_value_array[4] = {' ',' ',' ',' '};
int val;

const byte ROWS = 4; // Four rows
const byte COLS = 3; // Three columns
// Define the Keymap
char keys[ROWS][COLS] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte rowPins[ROWS] = { 13, 12, 11, 10 };
// Connect keypad COL0, COL1 and COL2 to these Arduino pins.
byte colPins[COLS] = { 9, 8, 7 }; 

// Create the Keypad
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );


  void setup() {

    // set up

    pinMode(5,OUTPUT);

    Serial.begin(9600);
    
    lcd.begin(16,2);   // iInit the LCD for 16 chars 2 lines
   
    lcd.print("KEYPAD LCD PWM"); 

  }

  void loop() 

  {
    BEGINNING: //Label for beginning
    key = kpd.waitForKey();
    if (key == '#' || key == '*'){
      //If key entered is # or *, go back to beginning
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
      
    }
     lcd.setCursor(0, 1);
    lcd.print("KEY= "+String(key)+"_");
    
    PWM_value_array[0] = key;

    delay(250);
   //Waiting for SECOND number
    key = kpd.waitForKey();
    if ( key != '*' && key != '#'){
      PWM_value_array[1] = key;
      lcd.setCursor(0, 1);
      lcd.print("KEY= "+String(PWM_value_array[0])+String(PWM_value_array[1])+"_");
    }
    Serial.println(key);
    if (key == '*'){
      //If key entered *, go back to beginning
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if(key == '#'){
      //We're done
      val = String(PWM_value_array[0]).toInt();
      goto ENDING;
      }
    delay(250);
    
      //Waiting on 3rd number
        key = kpd.waitForKey();
    if ( key != '*' && key != '#'){
      PWM_value_array[2] = key;
      lcd.setCursor(0, 1);
      lcd.print("KEY= "+String(PWM_value_array[0])+String(PWM_value_array[1])+String(PWM_value_array[2])+"_");
    }
    if (key == '*'){
      //If key entered *, go back to beginning
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if(key == '#'){
      //We're done
      val = String(String(PWM_value_array[0])+String(PWM_value_array[1])).toInt();
      goto ENDING;
      }
    delay(250);

     //Waiting on 4th character
        key = kpd.waitForKey();
    if ( key != '*' && key != '#'){
      lcd.setCursor(0, 1);
      lcd.print("NUMBER TOO LARGE");
      delay(1000);
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if (key == '*'){
      //If key entered *, go back to beginning
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if(key == '#'){
      //We're done
      val = String(String(PWM_value_array[0])+String(PWM_value_array[1])+String(PWM_value_array[2])).toInt();
      }

  ENDING:
  if(val > 255){
    val = 255;
  }
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("KEYPAD LCD PWM");
  lcd.setCursor(0, 1);
  lcd.print("KEY= ");
  
  Serial.println(val);

  analogWrite(5,val);
  
  }

Encoder Code:

#define encoder0PinA  2
#define encoder0PinB  4

volatile long encoder0Pos=0;
long newposition;
long oldposition = 0;
unsigned long newtime;
unsigned long oldtime = 0;
long vel;

void setup()
{
  pinMode(encoder0PinA, INPUT);
  digitalWrite(encoder0PinA, HIGH);       // turn on pullup resistor
  pinMode(encoder0PinB, INPUT);
  digitalWrite(encoder0PinB, HIGH);       // turn on pullup resistor
  attachInterrupt(0, doEncoder, RISING);  // encoDER ON PIN 2
  Serial.begin (9600);
  Serial.println("start");                // a personal quirk
}

void loop()
{
newposition = encoder0Pos;
newtime = millis();
vel = (newposition-oldposition)/600;
Serial.print ("speed = ");
Serial.println (vel);
oldposition = newposition;
oldtime = newtime;
delay(1000);
}

void doEncoder()
{
  if (digitalRead(encoder0PinA) == digitalRead(encoder0PinB)) {
    encoder0Pos++;
  } else {
    encoder0Pos--;
  }
}

PS. In my encoder code, I am not using time in calculation for the angular velocity but instead I used delay(1000). I believe there is a better way to do it. If you have any suggestion, please let me know. Thank you again.

2

It is not completely clear to me what your problem is. The second sketch does not use waitforkey().

Anyway, this is interesting:

    BEGINNING: //Label for beginning
    key = kpd.waitForKey();
    if (key == '#' || key == '*'){
      //If key entered is # or *, go back to beginning
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
     
    }

I don't often see examples of goto in C/C++ code. Of course it can be completely valid. In this case, it will be an endless loop until a '#' or '*' is entered. Is that what you want ?

3

it will be an endless loop until a '#' or '*' is entered

The construct loops only in the cases that # or * is entered, perhaps for number-only entry.

@OP: there is no need to use "waitForKey()". Use getKey() instead. It returns zero if no key is entered, so you can take any action you like. See Arduino Playground - HomePage

Note: it is a bad idea to use Strings on Arduino. They cause memory problems and program crashes.

lcd.print("KEY= "+String(key)+"_");
4

@6v6gt my apology for not stating it clear. What I meant is I use "waitforkey" in my main code, and when I try to merge with the encoder code, it hold up the process in the encoder because of the command "waitforkey" which results in the encoder does not work unless a key is pressed. My goal is I want it to run along with the main code without waiting for the key to be pressed.

@jremington I tried using "getKey()" and unfortunately it does not work. The LCD screen repeatedly displays "NUMBER IS TOO LARGE" and the encoder does not run. I might have done something wrong here. here is my maincode after merging with the encoder.

Please let me know if you have any suggestion. Thank you for your time.

#include <Keypad.h>
#include <Wire.h>  
#include <LiquidCrystal_I2C.h>
#define encoder0PinA  2
#define encoder0PinB  4

volatile long encoder0Pos=0;
long newposition;
long oldposition = 0;
unsigned long newtime;
unsigned long oldtime = 0;
long vel;


LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
char key;
char PWM_value_array[4] = {' ',' ',' ',' '};
int val;

const byte ROWS = 4; // Four rows
const byte COLS = 3; // Three columns
// Define the Keymap
char keys[ROWS][COLS] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte rowPins[ROWS] = { 13, 12, 11, 10 };
// Connect keypad COL0, COL1 and COL2 to these Arduino pins.
byte colPins[COLS] = { 9, 8, 7 }; 

// Create the Keypad
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );


  void setup() {

    // set up

    pinMode(5,OUTPUT);

    Serial.begin(9600);
    
    lcd.begin(16,2);   // iInit the LCD for 16 chars 2 lines
   
    lcd.print("KEYPAD LCD PWM"); 
    
     pinMode(encoder0PinA, INPUT);
  digitalWrite(encoder0PinA, HIGH);       // turn on pullup resistor
  pinMode(encoder0PinB, INPUT);
  digitalWrite(encoder0PinB, HIGH);       // turn on pullup resistor
  attachInterrupt(0, doEncoder, RISING);  // encoDER ON PIN 2
  Serial.begin (9600);
  Serial.println("start");                // a personal quirk

  }

  void loop() 

  {
    newposition = encoder0Pos;
newtime = millis();
vel = (newposition-oldposition)/600;
Serial.print ("speed = ");
Serial.println (vel);
oldposition = newposition;
oldtime = newtime;
delay(1000);

    BEGINNING: //Label for beginning
    key = kpd.getKey();
    if (key == '#' || key == '*'){
      //If key entered is # or *, go back to beginning
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
      
    }
     lcd.setCursor(0, 1);
    lcd.print("KEY= "+String(key)+"_");
    
    PWM_value_array[0] = key;

    delay(250);
   //Waiting for SECOND number
    key = kpd.getKey();
    if ( key != '*' && key != '#'){
      PWM_value_array[1] = key;
      lcd.setCursor(0, 1);
      lcd.print("KEY= "+String(PWM_value_array[0])+String(PWM_value_array[1])+"_");
    }
    Serial.println(key);
    if (key == '*'){
      //If key entered *, go back to beginning
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if(key == '#'){
      //We're done
      val = String(PWM_value_array[0]).toInt();
      goto ENDING;
      }
    delay(250);
    
      //Waiting on 3rd number
        key = kpd.getKey();
    if ( key != '*' && key != '#'){
      PWM_value_array[2] = key;
      lcd.setCursor(0, 1);
      lcd.print("KEY= "+String(PWM_value_array[0])+String(PWM_value_array[1])+String(PWM_value_array[2])+"_");
    }
    if (key == '*'){
      //If key entered *, go back to beginning
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if(key == '#'){
      //We're done
      val = String(String(PWM_value_array[0])+String(PWM_value_array[1])).toInt();
      goto ENDING;
      }
    delay(250);

     //Waiting on 4th character
        key = kpd.getKey();
    if ( key != '*' && key != '#'){
      lcd.setCursor(0, 1);
      lcd.print("NUMBER TOO LARGE");
      delay(1000);
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("KEYPAD LCD PWM");
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if (key == '*'){
      //If key entered *, go back to beginning
      lcd.setCursor(0, 1);
      lcd.print("KEY= ");
      goto BEGINNING;
    }
    if(key == '#'){
      //We're done
      val = String(String(PWM_value_array[0])+String(PWM_value_array[1])+String(PWM_value_array[2])).toInt();
      }

  ENDING:
  if(val > 255){
    val = 255;
  }
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("KEYPAD LCD PWM");
  lcd.setCursor(0, 1);
  lcd.print("KEY= ");
  
  Serial.println(val);

  analogWrite(5,val);
  
  }

    void doEncoder()
{
  if (digitalRead(encoder0PinA) == digitalRead(encoder0PinB)) {
    encoder0Pos++;
  } else {
    encoder0Pos--;
  }
}
5

unfortunately it does not work.

Of course it works. You are not using it correctly.

Check for a return of zero, which means no key is entered. Decide what should be done when no key is entered; what to do when a valid key is entered and write your program accordingly (as in the examples).