RE: Can BTLE communication happen without service discovery?

Hung Bui — Wed, 01 Nov 2017 09:30:09 GMT

We need a sniffer trace to see what exactly happens and why it takes 1.5s
Yes, it's possible, but you need to know the characteristic handle values, not the UUID. You can find those handle values after service discovery and then can hardcode it in your application. You can also use nRF Connect (on PC) to find the handle values.

RE: Can BTLE communication happen without service discovery?

endnode — Wed, 01 Nov 2017 07:12:33 GMT

Firstly if you use 7.5ms interval on Central side and your GATT Service Discovery takes still 1-1.5s then you must have hundred of handles on Server side (which is unlikely). So your Service Discovery algorithm looks suspicious;) Discovering the right handle (if you look for one particular Characteristic under one particular Service on a stack with 14 occupied GATT handles) should take less then 100ms.

Secondly sure GATT Service Discovery is purely matter of Client. If it is confident that it knows where the handles are then it doesn't need to do anything and fire Write/Read command straight after connection is established. You can have either static GATT Server side (so it can be cached/hardcoded on Server side) or you can hint some info through advertisement (if you have space there).