MPSL and BT Ticker

[JANC]

I am using nRF52840 boards. I have one query.

I understand from your documentation that MPSL schedules the Radio driver to access the Radio. And BT ticker is for time slots at the BLE level using Zephyr RTOS.

Are these modules either or feature/ Complement each other? They are independent sets at different levels?

kindly clarify

Thanks

[Priyanka]

Hi Janani,

Both MPSL and BLE ticker are different & separate components which operate at different levels. But they do work together as well in certain cases.

The MPSL is a set of libraries and it is a more lower layer (works below the BLE stack and Zephyr RTOS). It helps to schedule the radio hardware access for various protocols. 

The BLE ticker is a part of the Bluetooth stack in the Zephyr RTOS layer. It is used for BLE communication purposes and helps schedule time slots for various Bluetooth activities.

So it's the BLE ticker that schedules various BLE events and in case these events need radio access, the MPSL comes into picture. So these both cannot be called an either or feature as they operate at different levels and both are necessary for efficient operation of BLE and other protocols. Also, occasionally they do complement each other too.

-Priyanka

[JANC]

Thanks!!

Is there any silicon where multi protocol can be tested? Are the above modules MPSL and BLE ticker used in the latest  nRF SDK?

[Priyanka]

Yes, you can use our DKs like the nRF52840DK, nRF52833DK, nRF5340DK etc for testing the MPSL as these devices allow running another protocol in parallel with the SoftDevice Controller. The MPSL library is integrated into the nRF Connect SDK environment and is used in combination with the SoftDevice Controller to ensure multiprotocol support.

Indeed the MPSL and BLE ticker are included in the latest SDKs too.

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrfxlib/mpsl/README.html 

[JANC]

Thanks. Any particular Sample application that can be used for Bluetooth and 15.4?

[JANC]

Also, the radio scheduler is in HW level or at the firmware? I mean access to Radio is taken care by Firmware or the physical platform level?

[Priyanka]

There is the nRF5340_Multiprotocol RPMsg sample which you can take a look at. Also, the samples for application core, network core etc are mentioned here: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/app_dev/device_guides/nrf53/features_nrf53.html#multiprotocol_support_for_the_nrf5340_dk 

As for the radio scheduler, it operates in the firmware level. When the RADIO peripheral is used, the Radio Scheduler module in the firmware ensures that the HFCLK is running before starting the radio procedures. But, please do note that while the fw handles radio scheduling operations, the actual execution is carried out by the hardware, i.e. the firmware can schedule a radio operation to execute at a specific time in the future, but the operation itself is executed by the radio hardware.

-Priyanka

[JANC]

Thanks Priyanka. So the scheduler sits in the firmware and the radio peripheral or the HW takes care of TX/RX. There is no scheduler or PTA at the HW level I suppose. Is my understanding correct?

[Priyanka]

Yes that's right. The scheduler operates at the fw level.