Printing variable on state change only

Other Hardware Displays
1

Hello, I have a pretty simple question. I need to view the output of several pots on a LCD, but not in a continuous stream, just when it changes. I have some example code, but I'm embarrassed to say that it's just not enough. Can somebody use it in an example for me?

boolean PreviousValue;

void loop( void )
{
 boolean ThisValue;

 ThisValue = digitalRead( 7 );

 if ( ThisValue != PreviousValue )
 {
   // Your print goes here.
   PreviousValue = ThisValue;
 }
}
2

a refactored version of the code, I added a timestamp in the print to show when state change happened.

#define INPUTPIN 7

int previousValue = LOW;

void setup()
{
  Serial.begin(9600);
}

void loop( void )
{
  int value = digitalRead( INPUTPIN );

  if ( value != previousValue )
  {
    Serial.print(millis());
    Serial.print(" :  ");
    Serial.println(value);
     PreviousValue = value;
  }
  // do other things here
}

give it a try ..

3

Thanks Rob,

Ill try that, it seems much more clear. :slight_smile:

4

you're welcome, let us hear if it works and how you used it in your project