BLE Data packet length extension support with nRF5 SDK v12.0.0/Softdevice 332 v2.0.0

[TomH_Eng]

I need to port some functionality that is using nRF5 SDK 17.0.2/S332 SoftDevice v6.1.1 to an older firmware using nRF5 SDK v12.0.0/Softdevice 332 v2.0.0. It looks like Softdevice 332 v2.0.0 does not have the sd_ble_gap_data_length_update() or the BLE_GAP_EVT_DATA_LENGTH_* events.

I did find the sd_ble_opt_set() function and BLE_GAP_OPT_EXT_LEN option in v2.0.0. Does this provide the same functionality for setting up packet length extension using this older Softdevice version. Without the events to trigger this when should this option be set? Does this have to be done before any of the MTU changes? Are there any other Softdevice calls needed to enable this option?

If anyone has used this option before and has some suggestions or guidance on how to do this it would be much appreciated.

Regards,

Tom

[Susheel Nuguru]

Hi,

Before we proceed with this, can I ask you the reason to use such an old SDK and softdevice?

There are newer version of nRF5SDK with newer version of ANT stack available to make your products. Debugging issues on such an old version of solutions does not seem to be the best investment in time (unless you have a very strong reason not to use the latest SDK?)

[TomH_Eng]

Hi Susheel,

Thanks for the reply. I am currently making a change to a legacy firmware and want to add support for a feature that requires the BLE Data packet length extension. We are looking at migrating to the newest nRF5 SDK and Softdevice or possibly the nRF connect SDK but this will take a bit more time and planning. In the mean time we want to add the new feature to the current firmware.

Hope that makes sense.

Regards,

Tom

[Susheel Nuguru]

I think that BLE_GAP_EVT_DATA_LENGTH_ is introduced in Softdevice version 4.x.x. You might have to upgrade to SDK 15 atleast to be able to use this feature. I would strongly recommend you to use SDKv17.x if you are not able to switch to nRF Connect SDK for any reason.

[TomH_Eng]

Thanks for the information Susheel. I know updating to the newer SDK/Softdevice would be best and that is in to works. However my original questions still stands since right now, I need to do this within the limits of the current legacy firmware.

So do you have any advice that directly addresses the sd_ble_opt_set() function and BLE_GAP_OPT_EXT_LEN option in Softdevice v2.0.0 for using BLE Data packet length extension.

Regards,

Tom

[Susheel Nuguru]

You can still use BLE_GAP_OPT_EXT_LEN  in the version you are using but this is a static setting and cannot be changed. The feature that you are trying to port sd_ble_gap_data_length_update is a dynamic event length extension. 

If your application will be ok with static setting of event length at the time of softdevice enable, then you can use BLE_GAP_OPT_EXT_LEN. Dynamic requests wont work with this.