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modonewire.c
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modonewire.c
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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2015-2017 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 <stdint.h>
#include "py/obj.h"
#include "py/mphal.h"
#if MICROPY_PY_ONEWIRE
/******************************************************************************/
// Low-level 1-Wire routines
#define TIMING_RESET1 (480)
#define TIMING_RESET2 (70)
#define TIMING_RESET3 (410)
#define TIMING_READ1 (5)
#define TIMING_READ2 (5)
#define TIMING_READ3 (40)
#define TIMING_WRITE1 (10)
#define TIMING_WRITE2 (50)
#define TIMING_WRITE3 (10)
STATIC int onewire_bus_reset(mp_hal_pin_obj_t pin) {
mp_hal_pin_od_low(pin);
mp_hal_delay_us(TIMING_RESET1);
uint32_t i = mp_hal_quiet_timing_enter();
mp_hal_pin_od_high(pin);
mp_hal_delay_us_fast(TIMING_RESET2);
int status = !mp_hal_pin_read(pin);
mp_hal_quiet_timing_exit(i);
mp_hal_delay_us(TIMING_RESET3);
return status;
}
STATIC int onewire_bus_readbit(mp_hal_pin_obj_t pin) {
mp_hal_pin_od_high(pin);
uint32_t i = mp_hal_quiet_timing_enter();
mp_hal_pin_od_low(pin);
mp_hal_delay_us_fast(TIMING_READ1);
mp_hal_pin_od_high(pin);
mp_hal_delay_us_fast(TIMING_READ2);
int value = mp_hal_pin_read(pin);
mp_hal_quiet_timing_exit(i);
mp_hal_delay_us_fast(TIMING_READ3);
return value;
}
STATIC void onewire_bus_writebit(mp_hal_pin_obj_t pin, int value) {
uint32_t i = mp_hal_quiet_timing_enter();
mp_hal_pin_od_low(pin);
mp_hal_delay_us_fast(TIMING_WRITE1);
if (value) {
mp_hal_pin_od_high(pin);
}
mp_hal_delay_us_fast(TIMING_WRITE2);
mp_hal_pin_od_high(pin);
mp_hal_delay_us_fast(TIMING_WRITE3);
mp_hal_quiet_timing_exit(i);
}
/******************************************************************************/
// MicroPython bindings
STATIC mp_obj_t onewire_reset(mp_obj_t pin_in) {
return mp_obj_new_bool(onewire_bus_reset(mp_hal_get_pin_obj(pin_in)));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_reset_obj, onewire_reset);
STATIC mp_obj_t onewire_readbit(mp_obj_t pin_in) {
return MP_OBJ_NEW_SMALL_INT(onewire_bus_readbit(mp_hal_get_pin_obj(pin_in)));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_readbit_obj, onewire_readbit);
STATIC mp_obj_t onewire_readbyte(mp_obj_t pin_in) {
mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in);
uint8_t value = 0;
for (int i = 0; i < 8; ++i) {
value |= onewire_bus_readbit(pin) << i;
}
return MP_OBJ_NEW_SMALL_INT(value);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_readbyte_obj, onewire_readbyte);
STATIC mp_obj_t onewire_writebit(mp_obj_t pin_in, mp_obj_t value_in) {
onewire_bus_writebit(mp_hal_get_pin_obj(pin_in), mp_obj_get_int(value_in));
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(onewire_writebit_obj, onewire_writebit);
STATIC mp_obj_t onewire_writebyte(mp_obj_t pin_in, mp_obj_t value_in) {
mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in);
int value = mp_obj_get_int(value_in);
for (int i = 0; i < 8; ++i) {
onewire_bus_writebit(pin, value & 1);
value >>= 1;
}
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(onewire_writebyte_obj, onewire_writebyte);
STATIC mp_obj_t onewire_crc8(mp_obj_t data) {
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(data, &bufinfo, MP_BUFFER_READ);
uint8_t crc = 0;
for (size_t i = 0; i < bufinfo.len; ++i) {
uint8_t byte = ((uint8_t *)bufinfo.buf)[i];
for (int b = 0; b < 8; ++b) {
uint8_t fb_bit = (crc ^ byte) & 0x01;
if (fb_bit == 0x01) {
crc = crc ^ 0x18;
}
crc = (crc >> 1) & 0x7f;
if (fb_bit == 0x01) {
crc = crc | 0x80;
}
byte = byte >> 1;
}
}
return MP_OBJ_NEW_SMALL_INT(crc);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_crc8_obj, onewire_crc8);
STATIC const mp_rom_map_elem_t onewire_module_globals_table[] = {
{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_onewire) },
{ MP_ROM_QSTR(MP_QSTR_reset), MP_ROM_PTR(&onewire_reset_obj) },
{ MP_ROM_QSTR(MP_QSTR_readbit), MP_ROM_PTR(&onewire_readbit_obj) },
{ MP_ROM_QSTR(MP_QSTR_readbyte), MP_ROM_PTR(&onewire_readbyte_obj) },
{ MP_ROM_QSTR(MP_QSTR_writebit), MP_ROM_PTR(&onewire_writebit_obj) },
{ MP_ROM_QSTR(MP_QSTR_writebyte), MP_ROM_PTR(&onewire_writebyte_obj) },
{ MP_ROM_QSTR(MP_QSTR_crc8), MP_ROM_PTR(&onewire_crc8_obj) },
};
STATIC MP_DEFINE_CONST_DICT(onewire_module_globals, onewire_module_globals_table);
const mp_obj_module_t mp_module_onewire = {
.base = { &mp_type_module },
.globals = (mp_obj_dict_t *)&onewire_module_globals,
};
#endif // MICROPY_PY_ONEWIRE