onewire sample
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Outline
#include <string.h>
#include <stdbool.h>
#include "esp_check.h"
#include "esp_log.h"
#include "onewire_bus.h"
#include "onewire_device.h"
#include "onewire_crc.h"
#include "onewire_cmd.h"
TAG
onewire_device_iter_t
onewire_new_device_iter(onewire_bus_handle_t, onewire_device_iter_handle_t *)
onewire_del_device_iter(onewire_device_iter_handle_t)
onewire_device_iter_get_next(onewire_device_iter_handle_t, onewire_device_t *)
Files
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SourceVuESP-IDF Framework and Examplesonewire samplemanaged_components/espressif__onewire_bus/src/onewire_device.c
 
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/* * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Apache-2.0 *//* ... */ #include <string.h> #include <stdbool.h> #include "esp_check.h" #include "esp_log.h" #include "onewire_bus.h" #include "onewire_device.h" #include "onewire_crc.h" #include "onewire_cmd.h"8 includes static const char *TAG = "1-wire.device"; typedef struct onewire_device_iter_t { onewire_bus_handle_t bus; uint16_t last_discrepancy; bool is_last_device; uint8_t rom_number[sizeof(onewire_device_address_t)]; }{ ... } onewire_device_iter_t; esp_err_t onewire_new_device_iter(onewire_bus_handle_t bus, onewire_device_iter_handle_t *ret_iter) { ESP_RETURN_ON_FALSE(bus && ret_iter, ESP_ERR_INVALID_ARG, TAG, "invalid argument"); onewire_device_iter_t *iter = calloc(1, sizeof(onewire_device_iter_t)); ESP_RETURN_ON_FALSE(iter, ESP_ERR_NO_MEM, TAG, "no mem for device iterator"); iter->bus = bus; *ret_iter = iter; return ESP_OK; }{ ... } esp_err_t onewire_del_device_iter(onewire_device_iter_handle_t iter) { ESP_RETURN_ON_FALSE(iter, ESP_ERR_INVALID_ARG, TAG, "invalid argument"); free(iter); return ESP_OK; }{ ... } // Search algorithm inspired by https://www.analog.com/en/app-notes/1wire-search-algorithm.html esp_err_t onewire_device_iter_get_next(onewire_device_iter_handle_t iter, onewire_device_t *dev) { ESP_RETURN_ON_FALSE(iter && dev, ESP_ERR_INVALID_ARG, TAG, "invalid argument"); // we don't treat iterator ending and ESP_ERR_NOT_FOUND as an error condition, so just print debug message here if (iter->is_last_device) { ESP_LOGD(TAG, "1-wire rom search finished"); return ESP_ERR_NOT_FOUND; }{...} onewire_bus_handle_t bus = iter->bus; esp_err_t reset_result = onewire_bus_reset(bus); if (reset_result == ESP_ERR_NOT_FOUND) { ESP_LOGW(TAG, "reset bus failed: no devices found"); return ESP_ERR_NOT_FOUND; }{...} ESP_RETURN_ON_ERROR(reset_result, TAG, "reset bus failed"); // send rom search command and start search algorithm ESP_RETURN_ON_ERROR(onewire_bus_write_bytes(bus, (uint8_t[]) { ONEWIRE_CMD_SEARCH_NORMAL }{...}, 1), TAG, "send ONEWIRE_CMD_SEARCH_NORMAL failed"); uint8_t last_zero = 0; for (uint16_t rom_bit_index = 0; rom_bit_index < sizeof(onewire_device_address_t) * 8; rom_bit_index ++) { uint8_t rom_byte_index = rom_bit_index / 8; uint8_t rom_bit_mask = 1 << (rom_bit_index % 8); // calculate byte index and bit mask in advance for convenience uint8_t rom_bit = 0; uint8_t rom_bit_complement = 0; ESP_RETURN_ON_ERROR(onewire_bus_read_bit(bus, &rom_bit), TAG, "read rom_bit error"); // write 1 bit to read from the bus ESP_RETURN_ON_ERROR(onewire_bus_read_bit(bus, &rom_bit_complement), TAG, "read rom_bit_complement error"); // read a bit and its complement // No devices participating in search. if (rom_bit && rom_bit_complement) { ESP_LOGE(TAG, "no devices participating in search"); return ESP_ERR_NOT_FOUND; }{...} uint8_t search_direction; if (rom_bit != rom_bit_complement) { // There are only 0s or 1s in the bit of the participating ROM numbers. search_direction = rom_bit; // just go ahead }{...} else { // There are both 0s and 1s in the current bit position of the participating ROM numbers. This is a discrepancy. if (rom_bit_index < iter->last_discrepancy) { // current id bit is before the last discrepancy bit search_direction = (iter->rom_number[rom_byte_index] & rom_bit_mask) ? 0x01 : 0x00; // follow previous way }{...} else { search_direction = (rom_bit_index == iter->last_discrepancy) ? 0x01 : 0x00; // search for 0 bit first }{...} if (search_direction == 0) { // record zero's position in last zero last_zero = rom_bit_index; }{...} }{...} if (search_direction == 1) { // set corrsponding rom bit by search direction iter->rom_number[rom_byte_index] |= rom_bit_mask; }{...} else { iter->rom_number[rom_byte_index] &= ~rom_bit_mask; }{...} // set search direction ESP_RETURN_ON_ERROR(onewire_bus_write_bit(bus, search_direction), TAG, "write direction bit error"); }{...} // if the search was successful iter->last_discrepancy = last_zero; if (iter->last_discrepancy == 0) { // last zero loops back to the first bit iter->is_last_device = true; }{...} // check crc ESP_RETURN_ON_FALSE(onewire_crc8(0, iter->rom_number, 7) == iter->rom_number[7], ESP_ERR_INVALID_CRC, TAG, "bad device crc"); // save the ROM number as the device address memcpy(&dev->address, iter->rom_number, sizeof(onewire_device_address_t)); dev->bus = bus; ESP_LOGD(TAG, "new 1-Wire device found, address: %016llX", dev->address); return ESP_OK; }{ ... }
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