How to find 128 bit uuid services with sd_ble_gattc_primary_services_discover

RE: How to find 128 bit uuid services with sd_ble_gattc_primary_services_discover

mhassan@thoughttechnology.com — Mon, 23 Oct 2023 01:23:11 GMT

there are 2 important thing to discover 128bit or vendor specified UUIDs. first we should add the uuid by the sd_ble_uuid_vs_add function to discover them as known 128bit uuid. second is we should track found uuid end service handler value and use next number to start discovery again until reahing to 0xffff value. discovery can be done in several steps. in order to read complete 128bit uuid i'm still working on it i guess we should read data from gat or something.

     int cnt=p_prim_srvc_disc_rsp_evt->count;

    uint16_t      ServiceStartHandle = p_prim_srvc_disc_rsp_evt->services[cnt-1].handle_range.end_handle;
if (cnt> 0 && ServiceStartHandle != 0xffff)
{

StartDiscovery(ServiceStartHandle + 1);
Log("Continue Discovery from service handle 0x%04X.....", ServiceStartHandle);
}
else
{
Log("Discovery Finished ------------------------------");
}

RE: How to find 128 bit uuid services with sd_ble_gattc_primary_services_discover

Hung Bui — Fri, 02 Dec 2016 13:49:47 GMT

Hi Johnnie,

Is the "unknown" service UUID is known to the central in other words, the central knows which 128 bit UUID it's looking for ? Or it's a generic central and the peripheral's proprietary 128 bit UUID (s) are not known in advance to the central ?

If it's known for the central, the central should add the UUID base into the base UUID data base using sd_ble_uuid_vs_add (so there is a uuid_type bound to that UUID)

By doing that, you won't receive BLE_UUID_TYPE_UNKNOWN when receiving BLE_GATTC_EVT_PRIM_SRVC_DISC_RSP or BLE_GATTC_EVT_CHAR_DISC_RSP.

If you don't know in advance, then you have to accept BLE_UUID_TYPE_UNKNOWN then after that do a read with sd_ble_gattc_read() on the start handle received on that event. Then you will have the 128 bit UUID returned as the value of that handle.

After that you can add the UUID to get the uuid_type for that UUID if you want.

Note that by spec sd_ble_gattc_primary_service_discover() won't return all the UUID, it's only return the next (can be more than one) primary service. The client expected to call that again with Starting handle set to one greater than the last end handle. Check section 4.4.1 Vol 3 Part G in the Bluetooth Spec v4.2

I suggest to have a look at our ble_db_discovery.c library.

RE: How to find 128 bit uuid services with sd_ble_gattc_primary_services_discover

dbuijsma — Mon, 28 Nov 2016 17:15:54 GMT

Just to clarify: this question concerns the "pc-ble-driver" found here: github.com/.../pc-ble-driver

RE: How to find 128 bit uuid services with sd_ble_gattc_primary_services_discover

Johnnie — Mon, 28 Nov 2016 16:59:30 GMT

I have checked out the pc-ble-driver code which lists the version of software I am using as "SoftDevice s132 API version 3". Neither of these two symbols can be found in the sources ("find . -type f -exec grep DISCOVER {} ; -print" fails to find them).

RE: How to find 128 bit uuid services with sd_ble_gattc_primary_services_discover

FormerMember — Mon, 28 Nov 2016 12:30:47 GMT

The maximum number of services that a central/master will be searching for is defined by BLE_DB_DISCOVERY_MAX_SRV.
For the DB discovery module to search for a set of UUIDs, the UUIDs have to be added to the module using ble_db_discovery_evt_register().