0.25 -0.5 us delay repeated with 60 Hz frequency

Projects Programming
15

Is it solved by a code I misunderstood that outputs a pulse in microseconds?
Since post the code that outputs the actual nanosecond pulse, might as well.

enum pulseWidth {
  ns250_0, // 250.0ns
  ns312_5, // 312.5ns
  ns375_0, // 375.0ns
  ns437_5, // 437.5ns
  ns500_0  // 500.0ns
};
void setup() {
  pinMode(8, OUTPUT); // Pulse output is D8
}
void loop() {
  pulseBegin(60, ns250_0);     //   60Hz,250ns
  delay(3000);
  pulseBegin(1000, ns500_0);   //   1kHz,500ns
  delay(3000);
  pulseBegin(100000, ns500_0); // 100kHz,500ns
  delay(3000);
  pulseBegin(2.5, ns312_5);    //  2.5Hz,312.5ns
  delay(3000);
  pulseEnd(); // Pulse output disable
  delay(3000);
}
void pulseBegin(float Hz, unsigned char pW) { // Support 1Hz to 400kHz
  if (Hz <= 0) pulseEnd();
  else if  (Hz > 400000) pulseEnd();
  else {
    byte x = 0x18;
    if (Hz > (F_CPU >> 16)) {
      x += 1; Hz = F_CPU / Hz;
    } else if (Hz > (F_CPU >> 19)) {
      x += 2; Hz = (F_CPU >> 3) / Hz;
    } else if (Hz > (F_CPU >> 22)) {
      x += 3; Hz = (F_CPU >> 6) / Hz;
    } else {
      x += 4; Hz = (F_CPU >> 8) / Hz;
    }
    GPIOR2 = pW;
    TCCR1A = 0x03;
    cli();
    TIFR1  = 0x02;
    TIMSK1 = 0x02;
    TCCR1B = x;
    OCR1A  = Hz - 1;
    sei();
  }
}
void pulseEnd(void) {
  TIMSK1 = 0;
  TCCR1A = 0;
  TCCR1B = 0;
  GPIOR2 = 0;
}
ISR(TIMER1_COMPA_vect, ISR_NAKED) {
  __asm__ __volatile__ ( // 29cy + reti
    "push r30 \n in r30,0x3f \n push r30 \n push r31 \n"
    "ldi r30,lo8(gs(p_end)) \n in r31,0x2b \n sub r30,r31 \n"
    "ldi r31,hi8(gs(p_end)) \n sbci r31,0 \n sbi 0x05,0 \n"
    "ijmp \n nop \n nop \n nop \n nop \n p_end: cbi 0x05,0 \n"
    "pop r31 \n pop r30 \n out 0x3f,r30 \n pop r30 \n reti");
}
#if F_CPU != 16000000UL
#error "UNSUPPORTED CLOCK! RUN 16MHz ONLY!"
#endif

Pulse output pin is D8.
The pulse width can be selected from 5 types, 250ns to 500ns in 62.5ns steps.
(Because Arduino running at 16MHz, so one cycle is 62.5ns.)
The frequency can be set from 1Hz to 400kHz. (Decimal point allowed)

1 Like