Is it important to first add the advertising service UUID?

[Christopher Hunt]

Given a peripheral with BLE services A and B, if I advertise B but add A first during my services_init code, then the 16 bit UUID portion of B is added to A's long UUID. Is this intended behaviour i.e. should the service to be advertised always be added first? Certainly, if I add B first then the advertising UUID is correct.

[mrono]

This sounds familiar. Could it be similar to this case?

[Jared]

Thank you for sharing this thread. It might very well be similar to that case. 

[Christopher Hunt]

I'm not sure that they are the same issue as I'm using two custom services (a point of difference).

[mrono]

This line:

static ble_uuid_t m_adv_uuids[] = /**< Universally unique service identifiers. */
    {{B_SERVICE_UUID, BLE_UUID_TYPE_VENDOR_BEGIN}};

Basically says: take the 16 bits of B_SERVICE_UUID and the remaining bits from the beginning of the vendor specific UUIDs table.

And from your init code we can see that you add A_SERVICE first. So A_SERVICE_UUID_BASE will be the first entry in the vendor specific UUIDs table. And therefore BLE_UUID_TYPE_VENDOR_BEGIN will point to A_SERVICE_UUID_BASE.

So I still think it is the same issue. And that the way to fix it is to change the way the advertising uuid is defined.

[Christopher Hunt]

Thanks for the follow-up. Is it possible to see the documentation updated to reflect the fact that the ordering of declarations is important?

[mrono]

The order is important only if you use BLE_UUID_TYPE_VENDOR_BEGIN to specify the UUID to advertise. So it would be better to construct the m_adv_uuids[] differently and not rely on the order at all.