diff --git a/drivers/dht/dht.c b/drivers/dht/dht.c new file mode 100644 index 0000000000000000000000000000000000000000..04c590e0ce1dde981bd6a653c6b8f97d1f6056c7 --- /dev/null +++ b/drivers/dht/dht.c @@ -0,0 +1,104 @@ +/* + * 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 <stdio.h> + +#include "py/runtime.h" +#include "py/mperrno.h" +#include "py/mphal.h" +#include "drivers/dht/dht.h" + +STATIC mp_uint_t time_pulse_us(mp_hal_pin_obj_t pin, int pulse_value, mp_uint_t timeout) { + mp_uint_t start = mp_hal_ticks_us(); + while (mp_hal_pin_read(pin) != pulse_value) { + if ((mp_uint_t)(mp_hal_ticks_us() - start) >= timeout) { + return (mp_uint_t)-1; + } + } + start = mp_hal_ticks_us(); + while (mp_hal_pin_read(pin) == pulse_value) { + if ((mp_uint_t)(mp_hal_ticks_us() - start) >= timeout) { + return (mp_uint_t)-1; + } + } + return mp_hal_ticks_us() - start; +} + +STATIC mp_obj_t dht_readinto(mp_obj_t pin_in, mp_obj_t buf_in) { + mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in); + mp_hal_pin_open_drain(pin); + + mp_buffer_info_t bufinfo; + mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_WRITE); + + if (bufinfo.len < 5) { + nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "buffer too small")); + } + + // issue start command + mp_hal_pin_od_high(pin); + mp_hal_delay_ms(250); + mp_hal_pin_od_low(pin); + mp_hal_delay_ms(18); + + mp_uint_t irq_state = mp_hal_quiet_timing_enter(); + + // release the line so the device can respond + mp_hal_pin_od_high(pin); + mp_hal_delay_us_fast(10); + + // wait for device to respond + mp_uint_t ticks = mp_hal_ticks_us(); + while (mp_hal_pin_read(pin) != 0) { + if ((mp_uint_t)(mp_hal_ticks_us() - ticks) > 100) { + goto timeout; + } + } + + // time pulse, should be 80us + ticks = time_pulse_us(pin, 1, 150); + if (ticks == (mp_uint_t)-1) { + goto timeout; + } + + // time 40 pulses for data (either 26us or 70us) + uint8_t *buf = bufinfo.buf; + for (int i = 0; i < 40; ++i) { + ticks = time_pulse_us(pin, 1, 100); + if (ticks == (mp_uint_t)-1) { + goto timeout; + } + buf[i / 8] = (buf[i / 8] << 1) | (ticks > 48); + } + + mp_hal_quiet_timing_exit(irq_state); + return mp_const_none; + +timeout: + mp_hal_quiet_timing_exit(irq_state); + nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(MP_ETIMEDOUT))); +} +MP_DEFINE_CONST_FUN_OBJ_2(dht_readinto_obj, dht_readinto); diff --git a/drivers/dht/dht.h b/drivers/dht/dht.h new file mode 100644 index 0000000000000000000000000000000000000000..8274228ac6690c8e89faeb6dd0ba6a3d06c14e1a --- /dev/null +++ b/drivers/dht/dht.h @@ -0,0 +1,3 @@ +#include "py/obj.h" + +MP_DECLARE_CONST_FUN_OBJ(dht_readinto_obj);