81 lines
3.0 KiB
C
81 lines
3.0 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2016 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "py/runtime.h"
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#include "py/mperrno.h"
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#include "extmod/modmachine.h"
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#if MICROPY_PY_MACHINE_PULSE
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mp_uint_t machine_time_pulse_us(mp_hal_pin_obj_t pin, int pulse_level, mp_uint_t timeout_us) {
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mp_uint_t nchanges = 2;
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mp_uint_t start = mp_hal_ticks_us();
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for (;;) {
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// Sample ticks and pin as close together as possible, and always in the same
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// order each time around the loop. This gives the most accurate measurement.
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mp_uint_t t = mp_hal_ticks_us();
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int pin_value = mp_hal_pin_read(pin);
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if (pin_value == pulse_level) {
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// Pin is at desired value. Flip desired value and see if we are done.
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pulse_level = 1 - pulse_level;
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if (--nchanges == 0) {
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return t - start;
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}
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start = t;
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} else {
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// Pin hasn't changed yet, check for timeout.
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mp_uint_t dt = t - start;
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if (dt >= timeout_us) {
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return -nchanges;
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}
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// Allow a port to perform background task processing if needed.
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#ifdef MICROPY_PY_MACHINE_TIME_PULSE_US_HOOK
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MICROPY_PY_MACHINE_TIME_PULSE_US_HOOK(dt);
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#endif
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}
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}
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}
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static mp_obj_t machine_time_pulse_us_(size_t n_args, const mp_obj_t *args) {
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mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(args[0]);
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int level = 0;
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if (mp_obj_is_true(args[1])) {
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level = 1;
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}
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mp_uint_t timeout_us = 1000000;
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if (n_args > 2) {
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timeout_us = mp_obj_get_int(args[2]);
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}
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mp_uint_t us = machine_time_pulse_us(pin, level, timeout_us);
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// May return -1 or -2 in case of timeout
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return mp_obj_new_int(us);
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}
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MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_time_pulse_us_obj, 2, 3, machine_time_pulse_us_);
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#endif
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