Power consumption cannot be reduced after using hardware encryption

RE: Power consumption cannot be reduced after using hardware encryption

Vidar Berg — Fri, 28 Nov 2025 10:52:16 GMT

Hi,

Since I'm not able to reproduce this on my end I suggest you try to troubleshoot this more on your side. For example, you can try to build without FPU enabled (Note: this requires you to link in the non-FP variant of the cc310 runtime lib as well). Or you can try find you why you are not measuring -2-3 ua with the examples\crypto\nrf_cc310\aes example.

[quote user="mokoysh"] I'm sorry to misread the previous information,the project in the folder aes_test\.MDK_Project\AES_TEST.uvprojx.[/quote]

I see. I'm on macOS where directories with leading dot (.) like .MDK_Project will appear hidden by default.

RE: Power consumption cannot be reduced after using hardware encryption

mokoysh — Fri, 28 Nov 2025 01:16:28 GMT

Hi Vidar

Clear FPU interrupt before sd_app_evt_wait() can't resolve the problem, but __WFI resolve it.

RE: Power consumption cannot be reduced after using hardware encryption

Vidar Berg — Thu, 27 Nov 2025 11:53:16 GMT

sd_app_evt_wait() should behave like __WFE() and return when there is a pending interrupt. Still, the fact that you see lower current with __WFI() suggests that the problem is related to clearing of the FPU event and interrupt as Turbo mentioned. Did you try changing the order so that the FPU interrupt is cleared before the sd_app_evt_wait() and not after?

RE: Power consumption cannot be reduced after using hardware encryption

mokoysh — Thu, 27 Nov 2025 09:23:05 GMT

Thanks reply

I use __WFI() can reduce power but use sd_app_evt_wait() is still

RE: Power consumption cannot be reduced after using hardware encryption

mokoysh — Thu, 27 Nov 2025 09:20:33 GMT

Hi Vidar

I'm sorry to misread the previous information,the project in the folder aes_test\.MDK_Project\AES_TEST.uvprojx.

And i found use sd_app_evt_wait sleep is 3.4mA but use __WFI() will reduce power .

Can i use sd_app_evt_wait and __WFI() at same time?

RE: Power consumption cannot be reduced after using hardware encryption

Turbo J — Thu, 27 Nov 2025 09:04:07 GMT

Wr0ng order of operation in power_manage() function.

You need to kill FPU exceptions first, and then call sd_app_evt_wait().

Your order will wait for SD events with FPU enabled, and that may keep the MCU at high consumtion state.

EDIT: Did not see the ble stuff before posting. But if advertizer was inactive, the sd_app_evt_wait() call might never return.

RE: Power consumption cannot be reduced after using hardware encryption

Vidar Berg — Thu, 27 Nov 2025 08:29:32 GMT

Hi,

[quote user="mokoysh"]I test the examples\crypto\nrf_cc310\aes ,the power is 1.6mA. [/quote]

I measured ~2 ua with this example. The only change I made was to disable UART logging in sdk_config.h. Did you keep logging enabled?

[quote user="mokoysh"]And the project had attach[/quote]

The attachment included the source files, but I didn't see any actual project files for building the project.

RE: Power consumption cannot be reduced after using hardware encryption

mokoysh — Thu, 27 Nov 2025 01:59:25 GMT

Hi Vidar

I test the examples\crypto\nrf_cc310\aes ,the power is 1.6mA. Test chip is 52840,and the power is 17uA if no use aes_cbc_decrypt,power is 3.4mA if use aes_cbc_decrypt. And the project had attach

RE: Power consumption cannot be reduced after using hardware encryption

Vidar Berg — Wed, 26 Nov 2025 13:19:46 GMT

Hi,

I couldn't find any project files in your attachment, but I copied your decrypt function and ran it from the nRF5 SDK /nrf_cc310/aes/ project and was unable to reproduce the high current issue. Could you please try the same?

Best regards,

Vidar

RE: Power consumption cannot be reduced after using hardware encryption

mokoysh — Tue, 25 Nov 2025 12:24:33 GMT

devzone.nordicsemi.com/.../aes_5F00_test.7z

Hi Vidar

The project is attached

RE: Power consumption cannot be reduced after using hardware encryption

Vidar Berg — Tue, 25 Nov 2025 07:25:38 GMT

Thanks for confirming. Are you able to provide me a minimal sample that I can use to reproduce the issue here?

RE: Power consumption cannot be reduced after using hardware encryption

mokoysh — Tue, 25 Nov 2025 07:14:35 GMT

Hi Vidar

The aes_cbc_decrypt exe success and I will call sd_app_evt_wait in the main loop

RE: Power consumption cannot be reduced after using hardware encryption

Vidar Berg — Mon, 24 Nov 2025 12:18:40 GMT

Hi,

Generally we recommend using the nrf_crypto API on top of the cryptocell API (AES samples with cc310 can be found in /crypto/nrf_crypto/aes) which takes care of powering down the cc310 after use, but I see you ahavee SaSi_LibFini() at the end there which should have the same effect. Have you tried to debug your application to verify whether the program returns from this function and starts executing the __WFE()/__WFI() after?

Best regards,

Vidar