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[on:]

buenas a todos

no consigo encontrar el codigo de la funcion propia de arduino "pulsein" para ver que es lo que hace exactamente,

estoy trabajando en linux y he encontrado las librerias que estan en usr/share/arduino/libraries

pero las funciones por defecto de arduino no consigo  encontrarlas

alguien me podria informar?

gracias  

[Reply #1 on:]

Es esto lo que buscas?

Code:

unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
{
// cache the port and bit of the pin in order to speed up the
// pulse width measuring loop and achieve finer resolution.  calling
// digitalRead() instead yields much coarser resolution.
uint8_t bit = digitalPinToBitMask(pin);
uint8_t port = digitalPinToPort(pin);
uint8_t stateMask = (state ? bit : 0);
unsigned long width = 0; // keep initialization out of time critical area

// convert the timeout from microseconds to a number of times through
// the initial loop; it takes 16 clock cycles per iteration.
unsigned long numloops = 0;
unsigned long maxloops = microsecondsToClockCycles(timeout) / 16;

// wait for any previous pulse to end
while ((*portInputRegister(port) & bit) == stateMask)
if (numloops++ == maxloops)
return 0;

// wait for the pulse to start
while ((*portInputRegister(port) & bit) != stateMask)
if (numloops++ == maxloops)
return 0;

// wait for the pulse to stop
while ((*portInputRegister(port) & bit) == stateMask) {
if (numloops++ == maxloops)
return 0;
width++;
}

// convert the reading to microseconds. The loop has been determined
// to be 20 clock cycles long and have about 16 clocks between the edge
// and the start of the loop. There will be some error introduced by
// the interrupt handlers.
return clockCyclesToMicroseconds(width * 21 + 16);
}

El source para pulseIn() debes de encontrarlo en wiring_pulse.c

[Reply #2 on:]

perfecto, muchas gracias, era lo que buscaba