Use a button on LCD shield to pause the code

Question

I'm creating a Temperature logging device with thermocouple K and SD card breakout and a RGB LCD Shield Kit w/ 16x2 Character Display (with buttons).

Everything runs ok: temperature displaying on the LCD and logging on txt file on the micro SD card work well

Now I try to configure button on the shield

1. button UP to reset measurements and timer , it works

2. button Down to pause measurements, then when pushed again, continue measurements. I don't know how to do that (how to go out the while condition).

    if (buttons) {
   
   if (buttons & BUTTON_UP) {
   
     lcd.clear();
     lcd.print("RESET ");
     if (SD.exists("datalog.txt")) {
   
       SD.remove("datalog.txt");
       File dataFile = SD.open("datalog.txt", FILE_WRITE);
     }
   
     else {
   
       // open the file. note that only one file can be open at a time,
       // so you have to close this one before opening another.
       File dataFile = SD.open("datalog.txt", FILE_WRITE);
       // if the file is available, write to it:
   
     }
    StartTime = millis();
   
     delay(500);
   
   }
   if (buttons & BUTTON_DOWN) {
     lcd.clear();
     lcd.print("STOP");
     while (buttons & BUTTON_DOWN){
   
         ;
     }
   

   }

I already thank you for your help,

Vincent

Answer 1

You are not saying much about how buttons is valorized or its data type, but assuming it is a numeric variable which gets somehow set by, let's say a readButtons() function, then consider the following snippet replacing your while-loop:

do {
  delay(10);
  // re-evaluate whatever sets the buttons variable
  buttons = readButtons();
while(!(buttons & BUTTON_DOWN));

The loop above will continue until the button down is pressed and it's a little resilient regarding contact bouncing, but not 100% reliable, so I assume the readButtons() performs also some debouncing.