Support for secondary service discovery?

RE: Support for secondary service discovery?

pabigot — Wed, 14 Jan 2015 01:05:34 GMT

To expand on this just a little: you can replicate the behavior by iteratively calling sd_ble_gattc_char_value_by_uuid_read looking for attribute 0x2800 (primary) or 0x2801 (secondary) to retrieve the raw service UUIDs.

If you don't know the vendor UUID to pass to sd_ble_uuid_vs_add then the ble_uuid_t structures from sd_ble_gattc_primary_services_discover have type BLE_UUID_TYPE_UNKNOWN. The above process is how you would find the full UUID if it wasn't provided by an oracle.

RE: Support for secondary service discovery?

Ulrich Myhre — Sun, 11 Jan 2015 20:20:51 GMT

Hi,

As far as I know, it is mandatory to support the discovery of secondary services, even though they're not widely used. Our SoftDevices should have support for secondary service discovery since the very first versions, but not in an automated fashion like with the sd_ble_gattc_primary_services_discover function.

To discover secondary services, you will have to replicate some of the behavior that happens in that function, which means finding attributes with UUID 0x2801 ("Secondary Service") and then read their value to find the actual Service UUID. This UUID could be a vendor-specific UUID, and if this is the case there are some functions like sd_ble_uuid_decode that can help you filter your results in a clean way.

See this table and related pages for the adopted UUIDs.

If you want to experiment with secondary services, please read the Bluetooth Specification Vol 3, Part G, Chapter 3.1 and 3.2 very carefully. You have to include the secondary service in a primary service to be conformant with the specification.

RE: Support for secondary service discovery?

pabigot — Sat, 10 Jan 2015 19:24:55 GMT

The symptom I was trying to address was failure to find the vendor services on the TI SensorTag I'm using for experimentation, which are found by Bluez5's btgatt-client. Turns out that's not because they're secondary services, but because I was unaware of this trick.

However, the original question is still interesting so I'm not making this the answer.