printf(" -n: number of pulses to emit (default: 1)\n");
printf(" -f: frequency of pulses in hz (default: 1)\n");
printf(" -d: duty cycle [1, 255] (default: 128)\n");
printf(" -n: number of pulses to emit (default: 1)\n");
printf(" -f: frequency of pulses in hz (default: 1)\n");
printf(" -d: duty cycle [1, 255] (default: 128)\n");