scanning and connection establishment parameters

[Matej]

Hi,

I have a question about scan window and interval [I'm using nrf51822aa with s130 2.0.1... I performing some tests and I find a use case: If I set both of them (scan interval and window) to 0x140 - 200ms then radio scans all the time, after that I stop the scanning and create connection...

Once I get event that connection is established (with connection interval 20ms) I would like to start scanning once again - with same scanning params (interval 200ms and window 200ms) - What is from my perspective not possible because scanning procedure could not use radio for 100% if connection is established... but softdevice allows me to use such params (I get NRF_SUCCESS) - even it's not possible to work with such params or am I wrong? Of course none of device is found - once I use a bit more reasonable params (interval 200ms, window 50ms) everything works just fine

Now I am wondering how is this solved/protected in softdevice that user can set such things for scanning or creating connection params?

I expose softdevice functions to end user via API with all supported params, but I see that user could also enter/trigger some strange behaviour... Should I limited user at entering params considering on number of established connections?

Thank you for info.

Best regards, Matej

[Petter Myhre]

Yes, the SoftDevice will accept such parameters even though it has a connection. It will schedule connection and scanning events. See this for more information about scheduling.

The SoftDevice does not protect against this, it expect the user to select paramters that make sense.

I absolutely think it makes sense to limit the parameters the user can enter.

[Petter Myhre]

I guess you should, but it is up to you :) The central device dictates the connection interval, the peripheral can only request a connection parameter update, the central decides if it wants to accept or reject. See this MSC.