NRF52840 SPIM3 power consumption high after de-init

RE: NRF52840 SPIM3 power consumption high after de-init

Jørgen Holmefjord — Wed, 31 May 2023 08:18:30 GMT

[quote user="IvanS"]Are there any other known issues related to this SPIM3 module or any other connected one?[/quote]

I'm not aware of other issues related to SPIM3 than the ones listed in the errata document.

[quote user="IvanS"]Unfortunately this is a custom made PCB but I'll look into porting some of this onto DK board in case no other solution will appear.[/quote]

It would be very helpful if you could reproduce it on a DK and share an example, it would be hard for us to debug the issue and find the root cause if we are not able to reproduce it internally.

RE: NRF52840 SPIM3 power consumption high after de-init

IvanS — Thu, 25 May 2023 22:50:11 GMT

[quote userid="14926" url="~/f/nordic-q-a/100110/nrf52840-spim3-power-consumption-high-after-de-init/427551"]Do you always wait for the transfer(s) to complete before you uninit the driver?[/quote]

Yes, since I initiate them on NRF side.

[quote userid="14926" url="~/f/nordic-q-a/100110/nrf52840-spim3-power-consumption-high-after-de-init/427551"]I would expect the current consumption to be in the few uA range average current. What are you using to measure this?[/quote]

Yes, the overall consumption is pretty high, but I do not intend to go into a deep sleep right now. I use a resistor to measure consumption and simple watt measure.

[quote userid="14926" url="~/f/nordic-q-a/100110/nrf52840-spim3-power-consumption-high-after-de-init/427551"]Have you verified with a debugger that the line is executed when uniniting the driver?[/quote]

Unfortunately the whole system relies on another IC so I cannot do conventional step-debugger on NRF. I just verified it with the log lines and static variable assignment before and after the workaround in the NRF lib. They were in place, so I pretty sure that workaround is working for me.

[quote userid="14926" url="~/f/nordic-q-a/100110/nrf52840-spim3-power-consumption-high-after-de-init/427551"]Have you reproduced this on a nRF52840 DK? Can you share a minimal application we can use to reproduce the problem?[/quote]

Unfortunately this is a custom made PCB but I'll look into porting some of this onto DK board in case no other solution will appear.

Are there any other known issues related to this SPIM3 module or any other connected one?

RE: NRF52840 SPIM3 power consumption high after de-init

Jørgen Holmefjord — Thu, 25 May 2023 13:49:21 GMT

Hi,

[quote user=""]

I do the following:

1. Init SPIM3 (via nrfx_spim_init)
2. Exchange data with slave (via nrfx_spim_xfer)
3. Deinit SPIM3 (via nrfx_spim_uninit)
4. Suspend other peripherals and go to standby mode for several seconds.

[/quote]

Do you always wait for the transfer(s) to complete before you uninit the driver?

[quote user=""]I'm also measuring power consumption via a resistor placed between our power source and Nordic VDD[1-5] pins and the typical value is around 7 mW.[/quote]

7mW sounds like a lot if you have disabled all peripherals and put the chip in sleep mode. I would expect the current consumption to be in the few uA range average current. What are you using to measure this?

[quote user=""]But I've noticed that from time to time (approx 1/5) in the operational mode described above power consumption is 3 mW higher in standby mode.[/quote]

This could correlate with the ~900uA increased current from Errata 195.

[quote user=""]While investigating the issue I've checked that errata item 195 is already applied in the SDK I'm using.[/quote]

Have you verified with a debugger that the line is executed when uniniting the driver?

[quote user=""]

I've also tried to read-out chip registers and noticed that register 0x4002f518: has value 0x00 during normal consumption and 0x3e during increased level. But I was not able to find this register description in Datasheet.

Maybe someone can share this register description so I can check if it can be related to my power consumption issue?

[/quote]

This is an internal register, the description is not available publicly. I do not think this is related to the power consumption issue.

Have you reproduced this on a nRF52840 DK? Can you share a minimal application we can use to reproduce the problem?

Best regards,
Jørgen