I have a Timer1 frequency measurement program using the Input Capture Unit function from Nick Gammon's blog. it uses uses the D8 pin (ICP1) in the code as the input. How can I change the input pin to another digital pin like D7(AIN1?) or D5(T1?), or D2(INT0?), D3(INT1?), etc? Would that affect the Timer1 function? The Adafruit Feather 328 module I have does not have a D8 or is used for some other function.
Thank you!
// Duty cycle calculation using input capture unit
// Author: Nick Gammon
// Date: 5 November 2013
// Input: Pin D8
volatile boolean first;
volatile boolean triggered;
volatile unsigned long overflowCount;
volatile unsigned long startTime;
volatile unsigned long finishTime;
// timer overflows (every 65536 counts)
ISR (TIMER1_OVF_vect)
{
overflowCount++;
} // end of TIMER1_OVF_vect
ISR (TIMER1_CAPT_vect)
{
// grab counter value before it changes any more
unsigned int timer1CounterValue;
timer1CounterValue = ICR1; // see datasheet, page 117 (accessing 16-bit registers)
unsigned long overflowCopy = overflowCount;
// if just missed an overflow
if ((TIFR1 & bit (TOV1)) && timer1CounterValue < 0x7FFF)
overflowCopy++;
// wait until we noticed last one
if (triggered)
return;
if (first)
{
startTime = (overflowCopy << 16) + timer1CounterValue;
TIFR1 |= bit (ICF1); // clear Timer/Counter1, Input Capture Flag
TCCR1B = bit (CS10); // No prescaling, Input Capture Edge Select (falling on D8)
first = false;
return;
}
finishTime = (overflowCopy << 16) + timer1CounterValue;
triggered = true;
TIMSK1 = 0; // no more interrupts for now
} // end of TIMER1_CAPT_vect
void prepareForInterrupts ()
{
noInterrupts (); // protected code
first = true;
triggered = false; // re-arm for next time
// reset Timer 1
TCCR1A = 0;
TCCR1B = 0;
TIFR1 = bit (ICF1) | bit (TOV1); // clear flags so we don't get a bogus interrupt
TCNT1 = 0; // Counter to zero
overflowCount = 0; // Therefore no overflows yet
// Timer 1 - counts clock pulses
TIMSK1 = bit (TOIE1) | bit (ICIE1); // interrupt on Timer 1 overflow and input capture
// start Timer 1, no prescaler
TCCR1B = bit (CS10) | bit (ICES1); // plus Input Capture Edge Select (rising on D8)
interrupts ();
} // end of prepareForInterrupts
void setup ()
{
Serial.begin(115200);
Serial.println("Duty cycle width calculator");
// set up for interrupts
prepareForInterrupts ();
} // end of setup
void loop ()
{
// wait till we have a reading
if (!triggered)
return;
// period is elapsed time
unsigned long elapsedTime = finishTime - startTime;
Serial.print ("Took: ");
Serial.print (float (elapsedTime) * 62.5e-9 * 1e6); // convert to microseconds
Serial.println (" uS. ");
// so we can read it
delay (500);
prepareForInterrupts ();
} // end of loop
