PPI access in a radio timeslot?

[Bjorn191023]

Hi,

We are using nRF52840 with nRF5 SDK ver 16.0.0 with Softdevice S113 ver 7.0.1.

We use the radio timeslot to implement low level radio comm with very tight timing requirements. I wonder if we can use PPI in the timeslot?

The Softdevice spec (https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsds_s113%2FSDS%2Fs1xx%2Fconcurrent_multiprotocol_tsl_api%2Fconcurrent_multiprotocol_tsl_api.html&cp=4_6_1_0_8_1) says:

"When a Timeslot request is granted, the application has exclusive and real-time access to the normally blocked RADIO, TIMER0, CCM, and AAR peripherals and can use these freely for the duration (length) of the timeslot."

The Nordic guide (https://devzone.nordicsemi.com/nordic/short-range-guides/b/software-development-kit/posts/setting-up-the-timeslot-api) says:

"When a timeslot has been granted the application will gain access to the RADIO, TIMER0, CCM, AAR, and PPI(ch 14-15) modules for the duration of the timeslot."

So the spec does not mention PPI while the guide does.

Please clarify!

BR / Björn

[CheMax]

Hi,
I will answer based on my experience.

PPI module is just a peripheral module, part of the channels of which (0 - 19) can be used by the user for everything that is enough for imagination. and part of the channels, has a hard hardware configuration.

Custom channels can be used anywhere and anytime, nothing limit it.

Bjorn191023 said:

"When a timeslot has been granted the application will gain access to the RADIO, TIMER0, CCM, AAR, and PPI(ch 14-15) modules for the duration of the timeslot."

The peripherals used by the soft device are listed here. But at the time of gaining access to the time slot, it is free and you can use it to fit your needs.

I hope I understood your question correctly and my answer will be useful.

---

Best regards,

Max

[Edvin]

I agree with CheMax,

The PPI can be used as you like in a Timeslot, but don't use the PPIs that the softdevice use. You can see what PPI channels the softdevice uses by checking NRF_SOC_SD_PPI_CHANNELS_SD_ENABLED_MSK in nrf_soc.h, which is part of the softdevice header files. Search for it in your project.

So the rest you can use, as long as you don't use them anywhere else in your project.

Best regards,

Edvin

[Bjorn191023]

Hi Edvin,

Thanks, but I need a clarification.

I checked the mask and it reserves PPI channels 17 -31 to the Softdevice.

1) So I must not use PPI channels 17-31, not even in the timeslot?

2) So I can use PPI channels 0-16. Always or just in the timeslot?

BR / Björn

[CheMax]

Bjorn191023 said:

2) So I can use PPI channels 0-16. Always or just in the timeslot?

always.

Bjorn191023 said:

1) So I must not use PPI channels 17-31, not even in the timeslot?

with a successful open time slot, you get access to the radio and timer0. Is there access to pre-programmed channels (20 - 31) at this moment? I don’t know, but when using time slots, I did not have the need to access channels 20-31.

maybe there is no need for them in your task?

[Bjorn191023]

Hi CheMax,

Thanks for your response. I am currentlly not sure about my need. I am trying to learn the plaform, for this and future projects. That's why I requested a clarification from Nordic.

BR / Björn