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Microcontrollers

Category
Arduino

Arduino: Toggling Outputs

Did you know it is possible to toggle the state of a Arduino OUTPUT pin using a single line of code?  It’s true!  It’s also possible to use digitalRead() on an OUTPUT pin.  Assuming pin 13 was set to output, this single line of code will cause the LED to change state (or flash) each time it is called: 

digitalWrite(13, !digitalRead(13));
Keep reading to understand how these two tricks work.
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Arduino

Arduino: How do you reset millis() ?

The quick answer to “How do you reset millis()” is:  You Don’t!  And here’s why:  if you did, it would potentially break most libraries and functions that rely on it.  Generally the reason people want to reset it, is that they are concerned about rollover.  Instead of focusing on resetting millis(), here is how to use it correctly.

Need to brush up on how millis() works?  I’ve got a tutorial on how to effectively multi-task with millis() and another line-by-line tutorial on blink Without delay

Avoiding rollover and checking how much time as passed is done in a single line:

if ((unsigned long)(millis() - previousMillis) >= interval)

That single line of code is all that is really needed, to avoid rollover!  Pretty simple, huh?  So let’s go into more detail about how this works and what each of those variables does.

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