Using timeslot API and fds

RE: Using timeslot API and fds

bjorn-spockeli — Tue, 10 Mar 2020 13:49:09 GMT

Happy to help! 🙂

RE: Using timeslot API and fds

Bert Thomas — Tue, 10 Mar 2020 13:15:20 GMT

Yes, this solved it! It's working now as expected. Thanks!

RE: Using timeslot API and fds

bjorn-spockeli — Mon, 09 Mar 2020 09:49:02 GMT

Hi Bert,

It the Timer 0 Interrupt handler has a higher priority than 4, then calling the sd_- API will result in a HardFault, see Interrupt priority levels.

The priorities of the interrupts reserved by the SoftDevice cannot be changed. 
This includes the SVC interrupt. Handlers running at a priority level higher
than 4 (lower numerical priority value) have neither access to SoftDevice functions 
nor to application specific SVCs or RTOS functions running at lower priority levels
(higher numerical priority values).

So if the Timer0 handler has a higher priority than 4 you need to schedule the sd_radio_session_close() call to be called from a lower priority or from main's context.

Best regards

Bjørn

RE: Using timeslot API and fds

Bert Thomas — Mon, 09 Mar 2020 07:55:20 GMT

When I execute sd_radio_session_close() the softdevice code runs into the hardfault handler. Are you sure I can execute sd_radio_session_close() from the timer0 handler?

RE: Using timeslot API and fds

bjorn-spockeli — Thu, 05 Mar 2020 15:26:44 GMT

Ah, sorry Bert you are correct.

You should use the NRF_RADIO_CALLBACK_SIGNAL_TYPE_TIMER0 event, which should be generated about 100uS or so before the timeslot ends. So you either call sd_radio_session_close() here and then use the NRF_EVT_RADIO_SESSION_CLOSED event to trigger the Flash operations or you can start an application timer here to timeout after about 100us and use its timeout handler to initiate the flash operations.

It should be fine to call sd_radio_session_close while the timeslot is open, see https://devzone.nordicsemi.com/nordic/short-range-guides/b/software-development-kit/posts/setting-up-the-timeslot-api

RE: Using timeslot API and fds

Bert Thomas — Thu, 05 Mar 2020 13:36:27 GMT

Thanks for your reply!

At startup I invoke sd_radio_session_open(). Each time the timeslot has elapsed the timer0 handler returns NRF_RADIO_SIGNAL_CALLBACK_ACTION_REQUEST_AND_END to schedule the next timeslot. At what moment am I supposed to receive RADIO_SESSION_CLOSED event? Shouldn't I invoke sd_radio_session_close() to accomplish this? But I assume that to be able to execute sd_radio_session_close() the timeslot must have ended, right? So I'm confused...

RE: Using timeslot API and fds

bjorn-spockeli — Thu, 05 Mar 2020 12:37:45 GMT

Hi Bart,

it should be safe to call the sd_-API after you have received the NRF_EVT_RADIO_SESSION_CLOSED event, which indicates that the timeslot has been closed and the SoftDevice is in control of the peripherals it uses.

Best regards

Bjørn