MY NOME TIMER

JOHNWASSER_LEO

// Measures the HIGH width, LOW width, frequency and duty-cycle of a pulse train

// on Arduino UNO Pin 4 (ICP1 pin).

// Note: Since this uses Timer1, UNO Pin 9 and UNO Pin 10 can't be used for

// analogWrite().

void setup()

{

Serial.begin(115200);

while (!Serial);

// For testing on an UNO, uncomment one of these lines and connect

// Pin 3 or Pin 5 to Pin 4

//analogWrite(5, 64); // 512.00, 1528.00, 2040.00, 25.10%, 490.20 Hz

analogWrite(3, 64); // 260.00, 764.00, 1024.00, 25.39%, 976.56 Hz

noInterrupts (); // protected code

// reset Timer 1

TCCR1A = 0;

TCCR1B = 0;

TCNT1 = 0;

TIMSK1 = 0;

TIFR1 |= (1 << ICF1); // clear Input Capture Flag so we don't get a bogus interrupt

TIFR1 |= (1 << TOV1); // clear Overflow Flag so we don't get a bogus interrupt

TCCR1B = _BV(CS10) | // start Timer 1, no prescaler

_BV(ICES1); // Input Capture Edge Select (1=Rising, 0=Falling)

TIMSK1 |= _BV(ICIE1); // Enable Timer 1 Input Capture Interrupt

TIMSK1 |= _BV(TOIE1); // Enable Timer 1 Overflow Interrupt

interrupts ();

}

volatile uint32_t PulseHighTime = 0;

volatile uint32_t PulseLowTime = 0;

volatile uint16_t Overflows = 0;

ISR(TIMER1_OVF_vect)

{

Overflows++;

}

ISR(TIMER1_CAPT_vect)

{

static uint32_t firstRisingEdgeTime = 0;

static uint32_t fallingEdgeTime = 0;

static uint32_t secondRisingEdgeTime = 0;

uint16_t overflows = Overflows;

// If an overflow happened but has not been handled yet

// and the timer count was close to zero, count the

// overflow as part of this time.

if ((TIFR1 & _BV(TOV1)) && (ICR1 < 1024))

overflows++;

if (PulseLowTime == 0)

{

if (TCCR1B & _BV(ICES1))

{

// Interrupted on Rising Edge

if (firstRisingEdgeTime) // Already have the first rising edge...

{

// ... so this is the second rising edge, ending the low part

// of the cycle.

secondRisingEdgeTime = overflows;

secondRisingEdgeTime = (secondRisingEdgeTime << 16) | ICR1;

PulseLowTime = secondRisingEdgeTime - fallingEdgeTime;

firstRisingEdgeTime = 0;

}

else

{

firstRisingEdgeTime = overflows;

firstRisingEdgeTime = (firstRisingEdgeTime << 16) | ICR1;

TCCR1B &= ~_BV(ICES1); // Switch to Falling Edge

}

}

else

{

// Interrupted on Falling Edge

fallingEdgeTime = overflows;

fallingEdgeTime = (fallingEdgeTime << 16) | ICR1;

TCCR1B |= _BV(ICES1); // Switch to Rising Edge

PulseHighTime = fallingEdgeTime - firstRisingEdgeTime;

}

}

}

void loop()

{

noInterrupts();

uint32_t pulseHighTime = PulseHighTime;

uint32_t pulseLowTime = PulseLowTime;

interrupts();

// If a sample has been measured

if (pulseLowTime)

{

// Display the pulse length in microseconds

Serial.print("High time (microseconds): ");

Serial.println(pulseHighTime / 16.0, 2);

Serial.print("Low time (microseconds): ");

Serial.println(pulseLowTime / 16.0, 2);

uint32_t cycleTime = pulseHighTime + pulseLowTime;

Serial.print("Cycle time (microseconds): ");

Serial.println(cycleTime / 16.0, 2);

float dutyCycle = pulseHighTime / (float)cycleTime;

Serial.print("Duty cycle (%): ");

Serial.println(dutyCycle * 100.0, 2);

float frequency = (float)F_CPU / cycleTime;

Serial.print("Frequency (Hz): ");

Serial.println(frequency, 2);

Serial.println();

delay(500); // Slow down output

// Request another sample

noInterrupts();

PulseLowTime = 0;

interrupts();

}

}