Set Fixed Connection Interval and Event length on Central Side

[User1321]

Hi Nordic people, 

I've been working with the s140 for a long time now, having applications with our own central and peripheral device, but so far, the only way to make sure that I control the Connection interval is by setting the MAX and MIN value on the peripheral side to the same value. 

Is there a better way to do it on the Central side? 

On the central side, on the Connection Event: BLE_GAP_EVT_CONNECTED It's possible to read the suggested values from the current connection. 

In order to be able as central, to control this value is to force a sd_ble_gap_conn_param_update() with the same value as max and min.

Is there another way of doing it? The central is the one that decides the connection interval but i don't see any function on the s140 to fix it to ONE specific value. 

So far i have seen that a scheduling is not really possible from the programmer perspective, the s140 uses the event length, and similar with the connection interval.

I have an application where i want to connect several peripherals and based on the number of peripherals set a specific event length and connection interval. Is it possible to modify the event length according to our needs at run time?

Any help is welcomed, thank you very much. 

SDK17 btw! 

[Sigurd]

Hi,

I assume you use the Connection Parameters module. If the initial received parameters are not acceptable by the peripheral(not within max/min), it will send a connection parameters update request to the central, with the preferred connection parameters.

As the central, you control the initial connection interval. Set the max/min values used in sd_ble_gap_connect() to the same value, and make sure that this value is within the peripheral max/min limit, then you don't have to do a connection parameter update.

[User1321]

great, thank you!
What about the change of the event_length? is it possible to change it at run time, without the need of rebuilding the application? My question is related to both central and peripheral case.

[Sigurd]

You can setup several conn_cfg_tag with different event_length and choose between them in runtime. (when establishing the link, can't change it in the middle of a connection)

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s140.api.v7.3.0/structble__gap__conn__cfg__t.html