Custom 128bit UUID is Advertised Incorrectly

RE: Custom 128bit UUID is Advertised Incorrectly

mrono — Wed, 16 Oct 2019 05:36:39 GMT

[quote userid="5673" url="~/f/nordic-q-a/53123/custom-128bit-uuid-is-advertised-incorrectly/215194"]Would you be willing to expand more on how I could get the correct value at runtime in advertising_init() please![/quote]

Try something like this in advertising_init():

    static ble_uuid_t adv_uuid;
    adv_uuid.uuid = BLE_UUID_DCS_SERVICE;
    adv_uuid.type = m_cus.uuid_type;

    // ....
    
    init.advdata.uuids_complete.uuid_cnt = 1;
    init.advdata.uuids_complete.p_uuids  = &adv_uuid;

Once you have initialized the custom service then m_cus.uuid_type holds the correct index to that service's base UUID.

RE: Custom 128bit UUID is Advertised Incorrectly

k3nt — Wed, 16 Oct 2019 04:44:55 GMT

mrono and bjorn-spockeliThank you both for your responses! mrono, it does seem that you were correct in your suspicion. I am in fact using the dfu service and was initializing it before my own custom services. I tested moving the dfu service init to after my service inits and now the correct UUID base is being advertised. I also agree with you very strongly that this is not a suitable solution, and nowhere have I ever seen mention of the importance in the order of service inits in regards to advertising. Would you be willing to expand more on how I could get the correct value at runtime in advertising_init() please!

-Kent

RE: Custom 128bit UUID is Advertised Incorrectly

mrono — Tue, 15 Oct 2019 13:17:21 GMT

I agree that the issue is caused by the order of operations. A Nordic service, possibly DFU or NUS, is initialized first. Therefore the first VS UUID in the table is the Nordic one. However, I don't think relying on the order is the proper way to fix this.

In my opinion the error is right here:

static ble_uuid_t m_adv_uuids[] = {{BLE_UUID_DCS_SERVICE, BLE_UUID_TYPE_VENDOR_BEGIN}};

BLE_UUID_TYPE_VENDOR_BEGIN basically means "The index of the first vendor specific base UUID". Here you don't want the first base UUID, but specifically the base UUID of the DCS_SERVICE.

The correct base UUID is available from p_cus->uuid_type once the service has been initialized. So I'd forget the m_adv_uuids[]-array entirely and get the correct value at runtime in advertising_init().

RE: Custom 128bit UUID is Advertised Incorrectly

bjorn-spockeli — Tue, 15 Oct 2019 12:21:19 GMT

mrono: Thanks for sharing.
k3nt: Then there must be something with the order of the function calls that adds the VS UUID and populated the GATT table . If you have multiple vendor specific base UUIDs then you must call sd_ble_uuid_vs_add() before any sd_ble_gatts_service_add, sd_ble_gatts_characteristic_add or sd_ble_gatts_descriptor_add calls.

RE: Custom 128bit UUID is Advertised Incorrectly

mrono — Tue, 15 Oct 2019 11:51:11 GMT

That seems to be the Nordic base UUID (BLE_NORDIC_VENDOR_BASE_UUID), mixed with the custom service UUID.

I recall seeing this earlier. If you have two vendor specific base UUIDs, the way many Nordic examples are written don't specify which one do you want to use.

RE: Custom 128bit UUID is Advertised Incorrectly

bjorn-spockeli — Tue, 15 Oct 2019 09:36:35 GMT

Ok. Would you mind sharing the project folder? I would like to reproduce the issue here on a nRF52 DK. This would make it easier to debug.

Best regards

Bjørn

RE: Custom 128bit UUID is Advertised Incorrectly

k3nt — Mon, 14 Oct 2019 21:54:05 GMT

Hi Bjorn,

Yes, it returns 0 for both custom services.

RE: Custom 128bit UUID is Advertised Incorrectly

bjorn-spockeli — Mon, 14 Oct 2019 12:56:34 GMT

Hi Kent,

have you verified that sd_ble_uuid_vs_add() returns NRF_SUCCESS?

Best regards

Bjørn