ESP32 Forum

Posted: **Wed May 22, 2019 5:30 pm**

Hello,

I am using the

esp_ble_gatts_create_attr_tab

method of create a Bluetooth service.

I have two characteristics, and one of those characteristics has the notifications descriptor (0x2902) snippet below.

Code: Select all

static uint16_t sCharValueNotifications = 0b01;
...
    // Client Characteristic Configuration Descriptor - Enable notifications
    [BLE_HANDLE_CHAR_DESCR_NOTIFICATIONS] = {
        {ESP_GATT_AUTO_RSP}, 
        {
            ESP_UUID_LEN_16,
            (uint8_t *)&sUUIDReservedClientConfig, 
            ESP_GATT_PERM_READ | ESP_GATT_PERM_WRITE,
            sizeof(sCharValueNotifications), 
            sizeof(sCharValueNotifications), 
            (uint8_t*)&sCharValueNotifications
        }
    }

How do I notify subscribers of a characteristic that the characteristic has changed (i.e. has been written to)? Is there an API call, e.g. esp_ble_gatts_set_attr_value(), that will automatically send the notification to the connected devices?
I have seen examples using

Code: Select all

esp_ble_gatts_send_indicate

, but that would mean that I have to handle sending the notification in my event handler? Wouldn't that defeat the purpose of ESP_GATT_AUTO_RSP?

Posted: **Mon May 27, 2019 1:12 pm**

`ESP_GATT_AUTO_RSP` its different purpose. Its up to you if you want to send or not notifications or indications.

`ESP_GATT_AUTO_RSP` is to respond on requests from peer device, like read or write request to inform peer device that request has been accepted or rejected.

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