MPSL and timeslots using the radio fails with assert on nrf5340

[Andreas L]

Using latest master from NCS (61ed35f76bce079948aabb5bc752d7e0fd3a74b0).

I've modified the peripheral_lbs sample to request timeslots using mpsl (copied the example from samples/mpsl/timeslot) and changed the ble controller from zephyr to nordic ble_controller. The timeslot requests appears to work fine, but whenever I actually start the radio in my timeslot start event (TASKS_START= 1) I get an assert afterwards from the ble_controller:

BT_ERR("BleCtlr ASSERT: %s, %d", log_strdup(file), line);

where file is "../stack/libs/hal/src/hal_rcs.c" and line is 1543. 

As the mpsl is a binary, and the documentation is quite slim on how to actually implement this I would very much appreciate some help on how to proceed using the radio while in a MPSL timeslot - as well as what the assert above is actually complaining about.  The MPSL example in NCS is helpful in requesting timeslots, but it does not show any use of the radio peripheral. A simple skeleton show what needs to be done before the timeslot is closed etc would be very much appreciated. 

[Guojun Wang]

Hi Andreas,

You can only access radio within the request timeslot length (if approved).
The assert basically means you have used reserved peripherals (radio or timer0) outside the requested timeslot.

The MPSL library is very new into NCS, and more documentation will be added in the future.

Timeslot is ported from SoftDevice to MPSL. To have a better understanding how to use the radio peripheral within a timeslot session, you can take a look of the timeslot documentation in SoftDevice Specification, for instance https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsds_s140%2FSDS%2Fs1xx%2Fs140.html&cp=4_6_3_0.

For nRF53, there are also some limitations when you run application in the network core with ble_controller and mpsl: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.2.0/nrfxlib/ble_controller/doc/ble_controller.html

In addition:

1. Do you run the application in application core or in the network core?
2. It would be nice if you can provide a minimum code with instruction, so that we can re-produce the assert, if you still have this issue afterwards.

[Andreas L]

It turned out I left the radio in RX still after the timeslot had ended. I'll look at the softdevice documentation to get a better understanding of the functionality.

Thank you for the help!

[Guojun Wang]

Great! You are welcome.