delayMicroseconds not working on my Arduino Uno?

Projects Programming
1

Hi all,

I noticed that the function delayMicroseconds does not work (properly) on my Arduino Uno. It seems like the program skips the command altogether. For instance, in this simple program:

const int ledPin = 12;

void setup() {

  pinMode(ledPin, OUTPUT);
}

void loop() {
  
  digitalWrite(ledPin, HIGH);
  delayMicroseconds(500000);
  digitalWrite(ledPin, LOW);
  delayMicroseconds(500000);
  
  /*
  digitalWrite(ledPin, HIGH);
  delay(500);
  digitalWrite(ledPin, LOW);
  delay(500);
  */
}

the LED lights up at half capacity, as if it had a duty cycle of 50% (as you would expect when delayMicroseconds is being skipped). The normal delay function (in comments) works fine. A value of 500 ms in the delay function should be equivalent to 500000 µs in delayMicroseconds function, right? Anyone an idea what might be wrong?

2

Anyone an idea what might be wrong?

Yes, the delayMicroseconds() function is written to except a unsigned integer value. A value of 500000 will not fit into a integer. Here is the reference page for that function:
http://arduino.cc/en/Reference/DelayMicroseconds

Lefty

3

Ah, guess I didn't read the reference page thoroughly. Thanks!