0c13b95cdc
The 1-wire bus is defined with fixed timings so there should be no need to change them dynamically at runtime. Making the timings fixed saves about 270 bytes of code and 20 bytes of RAM.
163 lines
5.7 KiB
C
163 lines
5.7 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) 2015-2017 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 <stdint.h>
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#include "py/obj.h"
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#include "py/mphal.h"
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/******************************************************************************/
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// Low-level 1-Wire routines
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#define TIMING_RESET1 (480)
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#define TIMING_RESET2 (40)
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#define TIMING_RESET3 (420)
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#define TIMING_READ1 (5)
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#define TIMING_READ2 (5)
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#define TIMING_READ3 (40)
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#define TIMING_WRITE1 (10)
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#define TIMING_WRITE2 (50)
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#define TIMING_WRITE3 (10)
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STATIC int onewire_bus_reset(mp_hal_pin_obj_t pin) {
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mp_hal_pin_write(pin, 0);
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mp_hal_delay_us(TIMING_RESET1);
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uint32_t i = mp_hal_quiet_timing_enter();
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mp_hal_pin_write(pin, 1);
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mp_hal_delay_us_fast(TIMING_RESET2);
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int status = !mp_hal_pin_read(pin);
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mp_hal_quiet_timing_exit(i);
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mp_hal_delay_us(TIMING_RESET3);
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return status;
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}
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STATIC int onewire_bus_readbit(mp_hal_pin_obj_t pin) {
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mp_hal_pin_write(pin, 1);
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uint32_t i = mp_hal_quiet_timing_enter();
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mp_hal_pin_write(pin, 0);
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mp_hal_delay_us_fast(TIMING_READ1);
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mp_hal_pin_write(pin, 1);
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mp_hal_delay_us_fast(TIMING_READ2);
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int value = mp_hal_pin_read(pin);
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mp_hal_quiet_timing_exit(i);
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mp_hal_delay_us_fast(TIMING_READ3);
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return value;
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}
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STATIC void onewire_bus_writebit(mp_hal_pin_obj_t pin, int value) {
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uint32_t i = mp_hal_quiet_timing_enter();
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mp_hal_pin_write(pin, 0);
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mp_hal_delay_us_fast(TIMING_WRITE1);
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if (value) {
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mp_hal_pin_write(pin, 1);
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}
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mp_hal_delay_us_fast(TIMING_WRITE2);
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mp_hal_pin_write(pin, 1);
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mp_hal_delay_us_fast(TIMING_WRITE3);
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mp_hal_quiet_timing_exit(i);
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}
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/******************************************************************************/
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// MicroPython bindings
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STATIC mp_obj_t onewire_reset(mp_obj_t pin_in) {
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return mp_obj_new_bool(onewire_bus_reset(mp_hal_get_pin_obj(pin_in)));
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_reset_obj, onewire_reset);
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STATIC mp_obj_t onewire_readbit(mp_obj_t pin_in) {
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return MP_OBJ_NEW_SMALL_INT(onewire_bus_readbit(mp_hal_get_pin_obj(pin_in)));
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_readbit_obj, onewire_readbit);
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STATIC mp_obj_t onewire_readbyte(mp_obj_t pin_in) {
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mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in);
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uint8_t value = 0;
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for (int i = 0; i < 8; ++i) {
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value |= onewire_bus_readbit(pin) << i;
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}
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return MP_OBJ_NEW_SMALL_INT(value);
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_readbyte_obj, onewire_readbyte);
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STATIC mp_obj_t onewire_writebit(mp_obj_t pin_in, mp_obj_t value_in) {
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onewire_bus_writebit(mp_hal_get_pin_obj(pin_in), mp_obj_get_int(value_in));
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return mp_const_none;
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_2(onewire_writebit_obj, onewire_writebit);
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STATIC mp_obj_t onewire_writebyte(mp_obj_t pin_in, mp_obj_t value_in) {
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mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(pin_in);
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int value = mp_obj_get_int(value_in);
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for (int i = 0; i < 8; ++i) {
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onewire_bus_writebit(pin, value & 1);
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value >>= 1;
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}
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return mp_const_none;
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_2(onewire_writebyte_obj, onewire_writebyte);
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STATIC mp_obj_t onewire_crc8(mp_obj_t data) {
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mp_buffer_info_t bufinfo;
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mp_get_buffer_raise(data, &bufinfo, MP_BUFFER_READ);
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uint8_t crc = 0;
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for (size_t i = 0; i < bufinfo.len; ++i) {
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uint8_t byte = ((uint8_t*)bufinfo.buf)[i];
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for (int b = 0; b < 8; ++b) {
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uint8_t fb_bit = (crc ^ byte) & 0x01;
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if (fb_bit == 0x01) {
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crc = crc ^ 0x18;
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}
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crc = (crc >> 1) & 0x7f;
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if (fb_bit == 0x01) {
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crc = crc | 0x80;
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}
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byte = byte >> 1;
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}
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}
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return MP_OBJ_NEW_SMALL_INT(crc);
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_1(onewire_crc8_obj, onewire_crc8);
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STATIC const mp_map_elem_t onewire_module_globals_table[] = {
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{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_onewire) },
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{ MP_ROM_QSTR(MP_QSTR_reset), MP_ROM_PTR((mp_obj_t)&onewire_reset_obj) },
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{ MP_ROM_QSTR(MP_QSTR_readbit), MP_ROM_PTR((mp_obj_t)&onewire_readbit_obj) },
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{ MP_ROM_QSTR(MP_QSTR_readbyte), MP_ROM_PTR((mp_obj_t)&onewire_readbyte_obj) },
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{ MP_ROM_QSTR(MP_QSTR_writebit), MP_ROM_PTR((mp_obj_t)&onewire_writebit_obj) },
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{ MP_ROM_QSTR(MP_QSTR_writebyte), MP_ROM_PTR((mp_obj_t)&onewire_writebyte_obj) },
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{ MP_ROM_QSTR(MP_QSTR_crc8), MP_ROM_PTR((mp_obj_t)&onewire_crc8_obj) },
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};
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STATIC MP_DEFINE_CONST_DICT(onewire_module_globals, onewire_module_globals_table);
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const mp_obj_module_t onewire_module = {
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.base = { &mp_type_module },
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.globals = (mp_obj_dict_t*)&onewire_module_globals,
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};
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