esp-idf/examples/peripherals/rmt/onewire/main/onewire_example_main.c

/*
 * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Unlicense OR CC0-1.0
 */
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "esp_check.h"
#include "onewire_bus.h"
#include "ds18b20.h"

static const char *TAG = "example";

#define EXAMPLE_ONEWIRE_BUS_GPIO    0
#define EXAMPLE_ONEWIRE_MAX_DS18B20 2

void app_main(void)
{
    // install new 1-wire bus
    onewire_bus_handle_t bus;
    onewire_bus_config_t bus_config = {
        .bus_gpio_num = EXAMPLE_ONEWIRE_BUS_GPIO,
    };
    onewire_bus_rmt_config_t rmt_config = {
        .max_rx_bytes = 10, // 1byte ROM command + 8byte ROM number + 1byte device command
    };
    ESP_ERROR_CHECK(onewire_new_bus_rmt(&bus_config, &rmt_config, &bus));
    ESP_LOGI(TAG, "1-Wire bus installed on GPIO%d", EXAMPLE_ONEWIRE_BUS_GPIO);

    int ds18b20_device_num = 0;
    ds18b20_device_handle_t ds18b20s[EXAMPLE_ONEWIRE_MAX_DS18B20];
    onewire_device_iter_handle_t iter = NULL;
    onewire_device_t next_onewire_device;
    esp_err_t search_result = ESP_OK;

    // create 1-wire device iterator, which is used for device search
    ESP_ERROR_CHECK(onewire_new_device_iter(bus, &iter));
    ESP_LOGI(TAG, "Device iterator created, start searching...");
    do {
        search_result = onewire_device_iter_get_next(iter, &next_onewire_device);
        if (search_result == ESP_OK) { // found a new device, let's check if we can upgrade it to a DS18B20
            ds18b20_config_t ds_cfg = {};
            if (ds18b20_new_device(&next_onewire_device, &ds_cfg, &ds18b20s[ds18b20_device_num]) == ESP_OK) {
                ESP_LOGI(TAG, "Found a DS18B20[%d], address: %016llX", ds18b20_device_num, next_onewire_device.address);
                ds18b20_device_num++;
                if (ds18b20_device_num >= EXAMPLE_ONEWIRE_MAX_DS18B20) {
                    ESP_LOGI(TAG, "Max DS18B20 number reached, stop searching...");
                    break;
                }
            } else {
                ESP_LOGI(TAG, "Found an unknown device, address: %016llX", next_onewire_device.address);
            }
        }
    } while (search_result != ESP_ERR_NOT_FOUND);
    ESP_ERROR_CHECK(onewire_del_device_iter(iter));
    ESP_LOGI(TAG, "Searching done, %d DS18B20 device(s) found", ds18b20_device_num);

    // set resolution for all DS18B20s
    for (int i = 0; i < ds18b20_device_num; i++) {
        // set resolution
        ESP_ERROR_CHECK(ds18b20_set_resolution(ds18b20s[i], DS18B20_RESOLUTION_12B));
    }

    // get temperature from sensors one by one
    float temperature;
    while (1) {
        vTaskDelay(pdMS_TO_TICKS(200));

        for (int i = 0; i < ds18b20_device_num; i ++) {
            ESP_ERROR_CHECK(ds18b20_trigger_temperature_conversion(ds18b20s[i]));
            ESP_ERROR_CHECK(ds18b20_get_temperature(ds18b20s[i], &temperature));
            ESP_LOGI(TAG, "temperature read from DS18B20[%d]: %.2fC", i, temperature);
        }
    }
}