wiring_pulse.c

/*
  Arduino.c -  Partial implementation of the Wiring API for the Raspberry Pi
  Copyright (c) 2015 Hristo Gochkov.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include "Arduino.h"
#include "bcm2835_registers.h"

unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout){
  pinMode(pin, INPUT);
  uint32_t start = micros();
  while(digitalRead(pin) == state && (micros() - start) < timeout);
  while(digitalRead(pin) != state && (micros() - start) < timeout);
  start = micros();
  while(digitalRead(pin) == state && (micros() - start) < timeout);
  return micros() - start;
}