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Diffstat (limited to 'core/wiring_pulse.c')
-rwxr-xr-x | core/wiring_pulse.c | 66 |
1 files changed, 0 insertions, 66 deletions
diff --git a/core/wiring_pulse.c b/core/wiring_pulse.c deleted file mode 100755 index 8f232f1..0000000 --- a/core/wiring_pulse.c +++ /dev/null @@ -1,66 +0,0 @@ -/* - wiring_pulse.c - pulseIn() function - Part of Arduino - http://www.arduino.cc/ - - Copyright (c) 2005-2006 David A. Mellis - - 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., 59 Temple Place, Suite 330, - Boston, MA 02111-1307 USA - - $Id: wiring.c 248 2007-02-03 15:36:30Z mellis $ -*/ - -#include "wiring_private.h" -#include "pins_arduino.h" - -/* Measures the length (in microseconds) of a pulse on the pin; state is HIGH - * or LOW, the type of pulse to measure. Works on pulses from 2-3 microseconds - * to 3 minutes in length, but must be called at least a few dozen microseconds - * before the start of the pulse. */ -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) - width++; - - // convert the reading to microseconds. The loop has been determined - // to be 10 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 * 10 + 16); -} |