additional questions to nRF52832 Errata 220 clearification

RE: additional questions to nRF52832 Errata 220 clearification

dr71 — Tue, 10 Mar 2020 07:39:58 GMT

Hi Susheel,

thank you for clarifying how the workaround exactly works. This helps me to get a deeper understanding.

I implement the workaround and didn't see any side-effects till now. Therefore I will close this thread.

Thank you again,

Dirk

RE: additional questions to nRF52832 Errata 220 clearification

Susheel Nuguru — Sun, 08 Mar 2020 12:34:55 GMT

That is the reason we enabled the SEVONPEND bit now. So with this bit set, even the interrupts are disabled with these workaround, the internal events that generate the interrupt will be able to wake the chip. But the chip will be woken in the __WFE context and not in the interrupt context.

That is the main difference. When the chip wakes up it will enable the interrupts again and the application ISR will run as usual.

Before work around:
ENABLE_WAKEUP_SOURCE -> __WFE-> WAKEUP_SOURCE_ISR -> RERUN_FROM_ISR to next line of __WFE

After workaround
ENABLE_WAKEUP_SOURCE -> SEVONPEND -> DISABLE_INTERRUPTS -> __WFE -> WAKEUP to next line of __WFE -> ENABLE_interrupts -> WAKEUP_SOURCE_ISR

RE: additional questions to nRF52832 Errata 220 clearification

dr71 — Fri, 06 Mar 2020 13:11:15 GMT

Hi Susheel,

one point is still not 100% clear regarding interrupts.

The thing is I'm not sure if an interrupt also will publish an event if an interrupt occurs.
Example:

The uC is waiting for an interrupt (e.g. timer) than the __WFE() state is reached and with the workaround the interrupts are disabled. Did the interrupt result in triggering an event or do the ISR run later if another event happens and the interrupts are enabled at the end of the workaround?

We had in the past the situation in the startup phase where a __WFE() never returns.

Regards,

Dirk

RE: additional questions to nRF52832 Errata 220 clearification

Susheel Nuguru — Fri, 06 Mar 2020 09:09:20 GMT

I understand it :)

I am confident that it will turn out to be fine ...

RE: additional questions to nRF52832 Errata 220 clearification

dr71 — Fri, 06 Mar 2020 06:51:34 GMT

Hi Susheel,

thank you for clarify this. This will help us to decide how we deal with this errata.

Because I closed the last thread to early I will leave it open till it is implemented and tested.

Regards,

Dirk

RE: additional questions to nRF52832 Errata 220 clearification

Susheel Nuguru — Thu, 05 Mar 2020 12:45:51 GMT

Hi,

You just need to replace the sd_app_evt_wait() or any __WFE in your app wit the workaround mentioned in the ERRATA.

Even though you are not hit with this problem, it is a timing issue that could trigger it. I would recommend you to fix it instead of waiting for it to hit your devices in the long run.