Fritzing

High frequency sound that only youthful ears can hear

Flashing led shows the code is running

#include "mbed.h"

PwmOut speaker(p21);
DigitalOut myled(LED1);

int main() {
    speaker.period_us(62.5);
    speaker = 0.5;
 myled = 0;
 while (1) {
      myled = !myled;
     wait(1);
   }
}