Piezo speaker doesn't beep on battery power

[bugeye60]

Hello,

I'm using a Teensy 3.5 with a piezo speaker that beeps as expected when connected to power through USB. However, when I remove the USB and power it via batteries, sometimes the speaker beeps but usually it doesn't.

The setup is simply

pinMode(speakerPin, OUTPUT);

and the routine is

void Beep(int pitch, int duration)
{
  for (int j=1; j < duration; j++)
    {
      digitalWrite(speakerPin, HIGH);  // send 3.3 volts to the speaker pin
      delayMicroseconds(pitch);
      digitalWrite(speakerPin, LOW);  // remove voltage from the speaker pin
      delayMicroseconds(pitch);
    }
}

I'd be grateful for hints!

 

[PaulStoffregen]

Maybe try also turning on a LED, so you can watch if the Beep() code is running or now?

You could just connect the LED+resistor to the same pin. Rapid pulsing of the pin should appear as the LED on.

 

[KurtE]

As Paul, mentioned are you sure the code is executing?

Or maybe does your code hang some place. Example if you have code like: while (!Serial) ;
Which waits for the USB Serial to become available.

I would probably if possible toggle the LED each time this function is called to see if it is called (digitalWrite(13, !digitalRead(13));
Which assumes you already did a pinMode to OUTPUT earlier....

Also does your battery setup provide enough voltage/current to run properly?