51 lines
2.0 KiB
C
51 lines
2.0 KiB
C
/*
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pulse.c - wiring pulseIn implementation for esp8266
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Copyright (c) 2015 Hristo Gochkov. All rights reserved.
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This file is part of the esp8266 core for Arduino environment.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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//#include <limits.h>
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#include "wiring_private.h"
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#include "pins_arduino.h"
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extern uint32_t xthal_get_ccount();
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#define WAIT_FOR_PIN_STATE(state) \
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while (digitalRead(pin) != (state)) { \
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if (xthal_get_ccount() - start_cycle_count > timeout_cycles) { \
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return 0; \
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} \
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}
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// max timeout is 27 seconds at 160MHz clock and 54 seconds at 80MHz clock
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unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
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{
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const uint32_t max_timeout_us = clockCyclesToMicroseconds(UINT_MAX);
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if (timeout > max_timeout_us) {
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timeout = max_timeout_us;
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}
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const uint32_t timeout_cycles = microsecondsToClockCycles(timeout);
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const uint32_t start_cycle_count = xthal_get_ccount();
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WAIT_FOR_PIN_STATE(!state);
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WAIT_FOR_PIN_STATE(state);
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const uint32_t pulse_start_cycle_count = xthal_get_ccount();
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WAIT_FOR_PIN_STATE(!state);
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return clockCyclesToMicroseconds(xthal_get_ccount() - pulse_start_cycle_count);
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}
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unsigned long pulseInLong(uint8_t pin, uint8_t state, unsigned long timeout)
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{
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return pulseIn(pin, state, timeout);
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}
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