NRF52840 too high power consumption

[jonas.woerner]

Hi,

I know that this issue is well documented in the forum, but I have read everything and tried all of the suggested fixes, but nothing worked.

I am trying to Enter systemOFF mode and wake up from an external signal later.

when I enter systemOFF the chip draws about 60uA of power, which is way to much.

I made a small programm to test everything and found out, that using Interrupt pins will use a lot of power, but I thought, that this would only matter for systemON modes, as everything should get disabled in systemOFF mode... do I have to do anything else but

NRF_POWER->SYSTEMOFF = 1;

in order to get below 1uA?

my first thought was, that the chip may be in debug mode, but I uploaded the program, disconnected everything and then measured, and it was still that high.

my setup:

NRF52840-preview-DK + PowerProfilerKit.

Ps. when I have an empty int main() with only the systemOFF in it, I will get about 1uA power consumption, which is OK, but still strange as it should go lower?

[jonas.woerner]

Jørgen Holmefjord said:

I would expect mbed to use software cryptography for MBEDTLS by default

I verified it, mbedTLS definitly uses the Cryptocell hardware, you even have to initialize it, but you can turn it off and use software only if you wanted to.So I guess I will have to somehow disable the cryptocell310 before entering systemOFF.

[jonas.woerner]

I will mark this thread as answered and submit a sperate question for the cryptocell problem, as I think, others might be interested too.