esp-idf/examples/bluetooth/controller_hci_uart/main/controller_hci_uart_demo.c

/*
   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/

#include <stdio.h>
#include <string.h>
#include "nvs_flash.h"
#include "esp_bt.h"
#include "driver/uart.h"
#include "esp_log.h"

static const char *tag = "CONTROLLER_UART_HCI";

static void uart_gpio_reset(void)
{
#if CONFIG_BT_HCI_UART_NO == 1
    periph_module_enable(PERIPH_UART1_MODULE);
#elif CONFIG_BT_HCI_UART_NO == 2
    periph_module_enable(PERIPH_UART2_MODULE);
#endif
    periph_module_enable(PERIPH_UHCI0_MODULE);

#ifdef CONFIG_BT_HCI_UART_NO
    ESP_LOGI(tag, "HCI UART%d Pin select: TX 5, RX, 18, CTS 23, RTS 19", CONFIG_BT_HCI_UART_NO);

    uart_set_pin(CONFIG_BT_HCI_UART_NO, 5, 18, 19, 23);
#endif
}

void app_main()
{ 
    esp_err_t ret;

    /* Initialize NVS — it is used to store PHY calibration data */
    ret = nvs_flash_init();
    if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
        ESP_ERROR_CHECK(nvs_flash_erase());
        ret = nvs_flash_init();
    }
    ESP_ERROR_CHECK( ret );


    /* As the UART1/2 pin conflict with flash pin, so do matrix of the signal and pin */
    uart_gpio_reset();

    esp_bt_controller_config_t bt_cfg = BT_CONTROLLER_INIT_CONFIG_DEFAULT();
    ret = esp_bt_controller_init(&bt_cfg);
    if (ret != ESP_OK) {
        ESP_LOGE(tag, "Bluetooth Controller initialize failed: %s", esp_err_to_name(ret));
        return;
    }

    ret = esp_bt_controller_enable(ESP_BT_MODE_BTDM);
    if (ret != ESP_OK) {
        ESP_LOGE(tag, "Bluetooth Controller initialize failed: %s", esp_err_to_name(ret));
        return;
    }
}