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auto-plow / 71172f4

A wheelchair motor-propelled battery-powered ESP32-driven remote control snow plow.

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630 Nov 2018 18:364a63c8cInclude Arduino core filesJoshua1930N

Blob @ auto-plow / include / arduino / wiring_pulse.c

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1/*
2 wiring_pulse.c - pulseIn() function
3 Part of Arduino - http://www.arduino.cc/
4
5 Copyright (c) 2005-2006 David A. Mellis
6
7 This library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
11
12 This library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General
18 Public License along with this library; if not, write to the
19 Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20 Boston, MA 02111-1307 USA
21*/
22
23#include "wiring_private.h"
24#include "pins_arduino.h"
25
26/* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
27 * or LOW, the type of pulse to measure. Works on pulses from 2-3 microseconds
28 * to 3 minutes in length, but must be called at least a few dozen microseconds
29 * before the start of the pulse.
30 *
31 * This function performs better with short pulses in noInterrupt() context
32 */
33unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
34{
35 // cache the port and bit of the pin in order to speed up the
36 // pulse width measuring loop and achieve finer resolution. calling
37 // digitalRead() instead yields much coarser resolution.
38 uint8_t bit = digitalPinToBitMask(pin);
39 uint8_t port = digitalPinToPort(pin);
40 uint8_t stateMask = (state ? bit : 0);
41
42 // convert the timeout from microseconds to a number of times through
43 // the initial loop; it takes approximately 16 clock cycles per iteration
44 unsigned long maxloops = microsecondsToClockCycles(timeout)/16;
45
46 unsigned long width = countPulseASM(portInputRegister(port), bit, stateMask, maxloops);
47
48 // prevent clockCyclesToMicroseconds to return bogus values if countPulseASM timed out
49 if (width)
50 return clockCyclesToMicroseconds(width * 16 + 16);
51 else
52 return 0;
53}
54
55/* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
56 * or LOW, the type of pulse to measure. Works on pulses from 2-3 microseconds
57 * to 3 minutes in length, but must be called at least a few dozen microseconds
58 * before the start of the pulse.
59 *
60 * ATTENTION:
61 * this function relies on micros() so cannot be used in noInterrupt() context
62 */
63unsigned long pulseInLong(uint8_t pin, uint8_t state, unsigned long timeout)
64{
65 // cache the port and bit of the pin in order to speed up the
66 // pulse width measuring loop and achieve finer resolution. calling
67 // digitalRead() instead yields much coarser resolution.
68 uint8_t bit = digitalPinToBitMask(pin);
69 uint8_t port = digitalPinToPort(pin);
70 uint8_t stateMask = (state ? bit : 0);
71
72 unsigned long startMicros = micros();
73
74 // wait for any previous pulse to end
75 while ((*portInputRegister(port) & bit) == stateMask) {
76 if (micros() - startMicros > timeout)
77 return 0;
78 }
79
80 // wait for the pulse to start
81 while ((*portInputRegister(port) & bit) != stateMask) {
82 if (micros() - startMicros > timeout)
83 return 0;
84 }
85
86 unsigned long start = micros();
87 // wait for the pulse to stop
88 while ((*portInputRegister(port) & bit) == stateMask) {
89 if (micros() - startMicros > timeout)
90 return 0;
91 }
92 return micros() - start;
93}
94