Config and Pinout

[SteinC]

Hi, I'm using a WisBlock setup with:
• RAK19001 base board
• RAK4631 core
RAK18030 microphone in IO slot A
• RAK15002 microSD in IO slot B
I'm running Zephyr / nRF Connect SDK v3.2.4 on nRF52840.
The SD card works and WAV files are written correctly. The PDM driver also initializes and captures buffers successfully. However, the captured microphone data is not real audio. The raw blocks show a large startup transient, then an exponential decay, and then all samples become a constant value (around 7). Speaking or playing a tone directly into the microphone does not change the captured pattern.
We have already tested multiple PDM pin combinations in the Zephyr overlay, different channel selections, and also tried another microphone module. The behavior stays the same.
Could you please confirm the correct routing / pinapping / enable requirements for using RAK18030 on RAK19001 with RAK4631, specifically with RAK152 also installed in the other IO slot?

[Simonr]

Hei Stein

Takk for ærlige tilbakemeldinger!

I'll continue in English since other users might read this as it is a public ticket.

Regarding sleep and optimizing current consumption. With the nRF52840, the idle current consumption should be in the single digit µA range, even in power ON idle. Drawing 900+µA means something external is most likely running, as very few of the peripherals on the nRF52840 are able to draw that much power. I assume this is the whole system's current consumption, correct?

We released a Power optimization course on DevAcademy here https://academy.nordicsemi.com/courses/designing-low-power-bluetooth-le-products/lessons/lesson-1-power-consumption-essentials/?version=v3.3.0 and also have the optimization recommendations from our documentation pages here: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/test_and_optimize/optimizing/power_general.html 

In the Zephyr RTOS, the application should move to the idle thread (low power) as long as nothing else in the application is requesting any clocks/peripherals. So I assume either the microphone, SD card, or similar is left running in your application causing this 900µA current consumption.

Best regards,

Simon

[SteinC]

Hi, we have removed all io units from the Wisboard, measured the wisboard separate to 6 microamps, put the RAK4361 back in, still not gotten under 950µA. Got an example referred to us by RAK on Git but its to old using old PM routines. So we are struggling. Would be great to get a small example to verify that we understand the docs correctly. 

[Simonr]

Hi again Stein

What kind of sample are you looking for here? We don't test specifically with RAK boards since they are a third party module. But the low power sample projects in the previously linked DevAcademy course showcase how to put the device in a low power mode. Repos for that can be found here: https://github.com/NordicDeveloperAcademy/bt-lowpow 

Regarding the example you got from RAK, what nRF Connect SDK version is this based on? If it's not too long ago, migrating to a newer SDK version that supports the newer PM routines should be possible.

If you want to send us a couple of modules so we can try on our end, that's something we can do as well. It's hard for us to guess to what this 950µA comes from without having the HW ourselves.

Best regards,

Simon

[SteinC]

Hi, thanks for swift answer.

I was looking to get a code example for VSC that shows code for the RAK4631 is put to sleep. But i understand that you dont have units to test. RAK4631 contains nRF52840 the so i guess if u had the code for this to sleep then we could maybe get a better understanding?

As for the Github code from RAK i states that it uses SDK 3.1.3 but it uses the old PM style commends which u write was removed after version2.5 (there are several bits of code in that repository so parts of it may have been updated som the SDK ref is not correct).

We could send u kits if u are willing to test, but what would you actually need? Just RAK4631 or wisblock  etc.And where would we send it? My collegue is in Drøbak, Norway so it would be easy!!

Small extra question: the Github training reference you sent referers to nRF54. Do it also apply to nRF52840??

Thanks again!!

Best Regards Stein 

[Simonr]

Hi Stein

The Zephyr system OFF sample is built for the nRF52 series, so that should be usable for the RAK4631 as well as long as you have board files for it.

If you are to send us boards, we need a couple of boards with access to the SWD pins and details on how it should be powered and a description on how to get it up and running as well as any potential notes on what not to do with the board. We also need a board file reference to know how it generally should look. As for how we send it, I need to find someone else to take over this ticket as I'm on vacation as of next week. If you think that's the way to go, I'll find someone to take over this ticket and let you know if you should ship it to the Trondheim or Oslo office.

A lot of the concepts are the same for current consumption in the nRF52 and nRF54L series, so the Devacademy course should have a lot of relevance for the nRF52 series as well.

Best regards,

Simon