MPSL not working correctly with custom ble hci_rpmsg image

[duralabs]

We have been trying to get MPSL up and running in a BLE and ESB coexistence project but haven't had much luck.

We use an app core image that enables the BLE interface and listens for RPC events from the net core. The net core is a modified version of the BLE hci_rpmsg image with support added for RPC and ESB. We use RPC to notify the app core when data is received over ESB from other Nordic devices. BLE only needs to run for a short period of time and that period of time is user initiated. When implementing the MPSL piece, the BLE hci image is able to bind to "zephyr_bt_hci_rpmsg_ipc" but the "net_buf_get" while loop that delivers data to the app core is blocked from sending anything. We haven't been able to figure out how to allow "net_buf_get" to send BLE data to the app core once MPSL is implemented. 

When we init MPSL, we schedule a request to open a session and create a time slot. This process completes without any issues and we are notified that the time slot has begun. At this time, we'll enable ESB and send some data to a nearby nrf5340dk and that process is also successful. After this happens, we would assume that we would notify MPSL that the process has completed and that the bluetooth communication channel should be allowed to continue. 

We have reviewed the following MPSL sample projects but continue to run into errors with the bluetooth hci communication piece.

1. https://github.com/too1/ncs-esb-ble-mpsl-demo/tree/master
2. https://github.com/nrfconnect/sdk-nrf/tree/main/samples/mpsl/timeslot

Oddly enough, the bluetooth portion worked without any issues until we enabled the following kconfig values for MPSL.

CONFIG_MPSL=y
CONFIG_MPSL_TIMESLOT_SESSION_COUNT=2
CONFIG_RING_BUFFER=y
CONFIG_DYNAMIC_INTERRUPTS=y
CONFIG_DYNAMIC_DIRECT_INTERRUPTS=y

Are there any examples where MPSL is used for BLE and ESB coexistence on a board with an app core and a net core? Unfortunately the first link above looks like it runs on an older infrastructure that doesn't apply to our use-case. Any help would be appreciated as we've spent a lot of time trying to get MPSL working correctly.

[ovrebekk]

Hi Mike

The only sample showing how to run ESB and BLE in timeslot on the nRF53 is this one.

I have an ambition to update the ncs-esb-ble-mpsl-demo sample to run on the nRF53 as well, but I don't know how much time I will need to get this implemented. When I start work on this I will use the other sample for reference, no need to reinvent the wheel. 

Best regards
Torbjørn 

[duralabs]

Thanks for the response.

We tried building the project that you suggested but there are quite a few build errors. For the app core, the build complains about unknown type name 'NRF_RADIO_Type'. For the net core, the build complains about undefined reference to `mpsl_work_q'. 

For the NRF_RADIO_Type error, I see that nrf5340_network.h contains that definition but I'm unsure why the application core is trying to reference it.

Do you have any recommendations for getting the project to build correctly?

[ovrebekk]

Hi Mike

Can you be more specific what the WiFi hardware entails? Do you have an nRF7002 connected to the nRF5340? 

I would recommend opening a separate ticket on the WiFi issue, and include more information about the hardware and software involved, as well as the log output when the error occurs. 

Best regards
Torbjørn

[duralabs]

We are using the nrf7002 dk for the RX node and the nrf5340 dk for the TX node. I have no issue opening a new ticket. Will you be able to work on that new ticket? I think we'd make some quick progress given your experience with the esb and bluetooth coexistence logic of the project. 

[ovrebekk]

Hi Mike

If you mention my name, and the fact that I helped you out in this ticket, I expect it will be assigned to me as well

You can also include a link to the new case here. 

Best regards
Torbjørn

[duralabs]

I submitted another ticket and mentioned your name in the description. Thank you for all the support you've given so far. It is greatly appreciated. 

 Integrating wifi support into a BLE and ESB coexistence project 

[ovrebekk]

You welcome Mike, I will try to get back to you in the other ticket shortly