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