Errata 89 vs nRf52840 chip revisions

RE: Errata 89 vs nRf52840 chip revisions

Vidar Berg — Fri, 01 Apr 2022 10:01:13 GMT

Hi Anders,

[quote userid="111831" url="~/f/nordic-q-a/86460/errata-89-vs-nrf52840-chip-revisions/361181#361181"]So my guess is that the SPIS is entering transaction mode when SPI pins go low, and ends up in a state where the HF clocks remain active even after nrfx_spis_uninit call.[/quote]

This probably explains it. SPIS starts requesting the HF clock as soon as the chip select pin is asserted. But it should have been possible to disable the module while the CS was active.

I think it should ok to use the errata 89 workaround to get around this limitation.

RE: Errata 89 vs nRf52840 chip revisions

Anders Esbensen — Fri, 01 Apr 2022 09:48:37 GMT

Hi Vidar

I use TWIM0 , TWIM1, and SPIS2, so I expect no conflict between those.

When i see the increased power consumption it is typically after the SPI master (host) is powering down with SPIS on the nRF still active. So my guess is that the SPIS is entering transaction mode when SPI pins go low, and ends up in a state where the HF clocks remain active even after nrfx_spis_uninit call.

Most post in this forum as related to SPIM, so this might be a different variant of the issue.

RE: Errata 89 vs nRf52840 chip revisions

Vidar Berg — Fri, 01 Apr 2022 09:24:45 GMT

Hi Anders,

I think there must be a different root cause for the issue you are seeing even though the suggested workaround solves the problem. SPIS was not one of the affected peripheral according to the errata description, and I don't recall seeing this problem before either.

[quote user="Anders_e"]However it seem too still be relevant for SPIS mode.[/quote]

Agree. It seems like the SPIS keeps requesting the HF clock source until you apply the errata workaround. Are you using any other peripherals which share the same peripheral ID as your SPIS instance : Instantiation , Peripherals with shared ID ?

Best regards,

Vidar

RE: Errata 89 vs nRf52840 chip revisions

Anders Esbensen — Fri, 01 Apr 2022 08:08:38 GMT

Yes the excess current is ~400 uA and applying the workaround fixes the issue.

But according do documentation this workaround should not be necessary for newer chip revisions, since the Errata 89 has been marked fixed ?

However it seem too still be relevant for SPIS mode.

Br Anders

RE: Errata 89 vs nRf52840 chip revisions

Vidar Berg — Thu, 31 Mar 2022 10:17:10 GMT

Hi,

The idle current should be around ~400 uA if you encounter this errata. Does that correspond with what you are measuring, or is it only in 10-20 uA range? The latter could be the SPIS idle current. The errata workaround is effectively disabling the SPIS.

Best regards,

Vidar