ESP32 BLE Not Discoverable on Some Phones

[Modelox]

Hi everyone,

I'm trying to make my ESP32 discoverable via BLE on my phone. I tested it with the attached code, and it works well on my Galaxy S23 Ultra, I can see the device without any issues.

However, on some phones (e.g., iPhones), the device doesn't appear in the scan results. My goal is to have it function as a general BLE device without a specific profile (e.g., not HID). Ultimately, I want it to trigger a gate when I'm nearby.

Has anyone encountered this issue before? Any suggestions on making it universally discoverable?

Thanks in advance for your help!

Code: Select all

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "nvs_flash.h"
#include "esp_bt.h"
#include "esp_gap_ble_api.h"
#include "esp_gatts_api.h"
#include "esp_bt_main.h"

#define TAG "BLE"

// Callback for BLE events
static void gap_event_handler(esp_gap_ble_cb_event_t event, esp_ble_gap_cb_param_t *param) {
    switch (event) {
        case ESP_GAP_BLE_ADV_START_COMPLETE_EVT:
            if (param->adv_start_cmpl.status == ESP_BT_STATUS_SUCCESS) {
                ESP_LOGI(TAG, "BLE advertising started");
            } else {
                ESP_LOGE(TAG, "BLE advertising failed");
            }
            break;
        case ESP_GAP_BLE_ADV_STOP_COMPLETE_EVT:
            ESP_LOGI(TAG, "BLE advertising stopped");
            break;
        default:
            break;
    }
}

// Callback for GATT server events
static void gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_t gatts_if, esp_ble_gatts_cb_param_t *param) {
    switch (event) {
        case ESP_GATTS_CONNECT_EVT:
            ESP_LOGI(TAG, "Device connected");
            break;
        case ESP_GATTS_DISCONNECT_EVT:
            ESP_LOGI(TAG, "Device disconnected");
            esp_ble_gap_start_advertising(NULL); // Restart advertising
            break;
        default:
            break;
    }
}

extern "C" void app_main() {
    // Initialize NVS
    esp_err_t 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);

    // Initialize BLE
    ESP_ERROR_CHECK(esp_bt_controller_mem_release(ESP_BT_MODE_CLASSIC_BT));
    esp_bt_controller_config_t bt_cfg = BT_CONTROLLER_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_bt_controller_init(&bt_cfg));
    ESP_ERROR_CHECK(esp_bt_controller_enable(ESP_BT_MODE_BLE));
    ESP_ERROR_CHECK(esp_bluedroid_init());
    ESP_ERROR_CHECK(esp_bluedroid_enable());

    // Register GAP and GATT events
    ESP_ERROR_CHECK(esp_ble_gap_register_callback(gap_event_handler));
    ESP_ERROR_CHECK(esp_ble_gatts_register_callback(gatts_event_handler));

    // Set advertising data
    esp_ble_adv_data_t adv_data = {
        .set_scan_rsp = false,
        .include_name = true,
        .include_txpower = false,
        .min_interval = 0x20,
        .max_interval = 0x40,
        .appearance = 0x00,
        .manufacturer_len = 0,
        .p_manufacturer_data = NULL,
        .service_data_len = 0,
        .p_service_data = NULL,
        .service_uuid_len = 0,
        .p_service_uuid = NULL,
        .flag = ESP_BLE_ADV_FLAG_GEN_DISC | ESP_BLE_ADV_FLAG_BREDR_NOT_SPT,
    };
    ESP_ERROR_CHECK(esp_ble_gap_config_adv_data(&adv_data));

    // Start advertising
    esp_ble_adv_params_t adv_params = {
        .adv_int_min = 0x20,
        .adv_int_max = 0x40,
        .adv_type = ADV_TYPE_IND,
        .own_addr_type = BLE_ADDR_TYPE_PUBLIC,
        .channel_map = ADV_CHNL_ALL,
        .adv_filter_policy = ADV_FILTER_ALLOW_SCAN_ANY_CON_ANY,
    };
    ESP_ERROR_CHECK(esp_ble_gap_start_advertising(&adv_params));

    ESP_LOGI(TAG, "BLE initialized and advertising");
}