Condition on variable change?

Elec_Prog

Hi, how could I write an if statement that triggers when the value of a variable changes? The value is being read from serial and might be a certain integer for a number of loops, then increment by 1. I want something to happen when that increase occurs.

GoToLoop

• Serial library already got a trigger called serialEvent().
• Just declare some global boolean variable in order to flag the special event.
• Inside serialEvent(), set the boolean flag to true.
• Inside draw(), check whether the flag is true and execute the special action if so.
• After the special action is done, unset the flag to false.

Elec_Prog

I think what you describe will work if I go back and change the Arduino code to only transmit to serial when a certain threshold on my sensor is reached (currently it constantly outputs a count of events). I'll give it a shot, thanks.

TfGuy44

Otherwise you can record the last value seen in a global variable, and when it changes from that value, the event triggers.

int glob;

if ( val != glob ){
  glob = val;
  event();
}