95 lines
3.0 KiB
C
95 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 <stdio.h>
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#include "py/runtime.h"
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#include "py/mperrno.h"
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#include "py/mphal.h"
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#include "extmod/machine_pulse.h"
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#include "drivers/dht/dht.h"
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// Allow the open-drain-high call to be DHT specific for ports that need it
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#ifndef mp_hal_pin_od_high_dht
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#define mp_hal_pin_od_high_dht mp_hal_pin_od_high
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#endif
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STATIC mp_obj_t dht_readinto(mp_obj_t pin_in, mp_obj_t buf_in) {
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mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in);
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mp_hal_pin_open_drain(pin);
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mp_buffer_info_t bufinfo;
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mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_WRITE);
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if (bufinfo.len < 5) {
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mp_raise_ValueError(MP_ERROR_TEXT("buffer too small"));
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}
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// issue start command
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mp_hal_pin_od_high_dht(pin);
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mp_hal_delay_ms(250);
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mp_hal_pin_od_low(pin);
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mp_hal_delay_ms(18);
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mp_uint_t irq_state = mp_hal_quiet_timing_enter();
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// release the line so the device can respond
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mp_hal_pin_od_high_dht(pin);
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mp_hal_delay_us_fast(10);
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// wait for device to respond
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mp_uint_t ticks = mp_hal_ticks_us();
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while (mp_hal_pin_read(pin) != 0) {
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if ((mp_uint_t)(mp_hal_ticks_us() - ticks) > 100) {
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goto timeout;
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}
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}
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// time pulse, should be 80us
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ticks = machine_time_pulse_us(pin, 1, 150);
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if ((mp_int_t)ticks < 0) {
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goto timeout;
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}
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// time 40 pulses for data (either 26us or 70us)
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uint8_t *buf = bufinfo.buf;
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for (int i = 0; i < 40; ++i) {
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ticks = machine_time_pulse_us(pin, 1, 100);
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if ((mp_int_t)ticks < 0) {
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goto timeout;
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}
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buf[i / 8] = (buf[i / 8] << 1) | (ticks > 48);
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}
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mp_hal_quiet_timing_exit(irq_state);
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return mp_const_none;
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timeout:
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mp_hal_quiet_timing_exit(irq_state);
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mp_raise_OSError(MP_ETIMEDOUT);
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}
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MP_DEFINE_CONST_FUN_OBJ_2(dht_readinto_obj, dht_readinto);
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