Turning off unused RAM to get minimum power consumption.

RE: Turning off unused RAM to get minimum power consumption.

Hung Bui — Mon, 17 Jul 2023 11:37:02 GMT

Hi again Adam,

I'm sorry for the late response. We are a bit low on staff in the summer.

I just want to share some update on my measurement.

I edited the RTC example for testing.
Here is my code to turn off RAM retention:

I have to retain RAM[8], most likely because the stack is located at the top of RAM.

Here is with full ram Retention (RAM_RETENTION=1):

Here is after turn off most blocks (set RAM_RETENTION=0)

You can find that the current consumption dropped almost 1.6uA. This matched with the calculation from our expert in the email thread with Gene.

I found that nRF_POWER->RAM[8] plays an important role in the power consumption. If I don't put RAM[8] (part of it) into OFF mode, I will have this:

So the current dropped only 0.60 uA when RAM[8] was in full retention.

I was testing with PCA10056 DK v3.0 with PPK2 in Ampere mode. My suggestion is to try switch SW6 to nRFOnly if you don't see low current consumption in your measurement to avoid leakage current to other components on the board. As power reset between each measurement is also suggested.

devzone.nordicsemi.com/.../rtc-_2D00_-Ramretention.zip

RE: Turning off unused RAM to get minimum power consumption.

Hung Bui — Thu, 13 Jul 2023 09:10:47 GMT

Hi Adam,

Håkon is on vacation and I will take over the ticket. Due to reduced staff in the summer there will be some delay in our response. I'm sorry for that.

RE: Turning off unused RAM to get minimum power consumption.

Adam Cook — Fri, 07 Jul 2023 15:50:26 GMT

I have tried that an not measured any noticeable difference. Could there be other components on the DK that could be consuming extra power?

RE: Turning off unused RAM to get minimum power consumption.

Håkon Alseth — Fri, 07 Jul 2023 12:55:10 GMT

Hi,

You should set the NRF_POWER->RAM[0].POWER when setting blocks directly with a mix of '0' and '1'.

SET / CLR registers has to be written '1' to in order to perform a specific set or clear task.

For more info, see this chapter:

https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=5_0_0_4_2_6_20#register.RAM-0-8.POWER

Kind regards,

Håkon