SERVICE SOLICITATION

[Jim]

In the broadcast field, what is the difference between "SERVICE SOLICITATION", "SERVICE UUID" and " SERVICE DATA "?What does it do?In what scene?

[Bjørn Kvaale]

Hi,

The Service UUID is the main way a device is able to identify a particular service. This can either be a 16 bit service UUID for predefined Bluetooth SIG services (e.g. heart rate service UUID = 0x180D) or a 128-bit custom service. (aka vendor specific UUID). See Bluetooth Core Specifications Version 5.0 or the services tutorial for more info.

I believe what you mean by service data can be summarized by this struct, which can be found in ble_advdata.h (e.g. in sdk 14.2 ble_app_blinky example)

/**@brief Service data structure. */
typedef struct
{
    uint16_t                     service_uuid;                        /**< Service UUID. */
    uint8_array_t                data;                                /**< Additional service data. */
} ble_advdata_service_data_t;

This struct contains both the service_uuid which I mentioned previously & extra service data.

Could you explain what you mean by SERVICE SOLICATION? Are you referring to a specific variable, such as BLE_GAP_AD_TYPE_SOLICITED_SERVICE_UUIDS_16BIT or BLE_GAP_AD_TYPE_SOLICITED_SERVICE_UUIDS_128BIT or something else?

[Jim]

        I saw in the ble_app_ancs_c routine, the broadcast initialization function has the following definition：

        init.advdata.uuids_solicited.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
        init.advdata.uuids_solicited.p_uuids = m_adv_uuids; 

         In the above usage scenario, what is the definition of the "BLE_GAP_AD_TYPE_SOLICITED_SERVICE_UUIDS_128BIT " field in the broadcast data? Is it necessary?

[Bjørn Kvaale]

The BLE_GAP_AD_TYPE_SOLICITED_SERVICE_UUIDS_128BIT is used for the 128 bit custom services. Does not seem that it is used all too much though. Seems like it may be used for background scanning on iOS devices, so in this example it may be required. See the doc here for more info.