Current Measurement on nRF5340 DK

[Frikkie Badenhorst]

Hi there, 

We are currently doing current measurements on the nRF5340 DK with a Power Profiler Kit 2.

To do this, we simply use the PPK as a source meter and connect it to the "External Supply" pin. We also set SW10 to on (VEXT->nRF).

We leave the the USB connected to the interface MCU in order to communicate via UART.

However, we are measuring a current of 6mA for this which is quite high, as the only peripheral we are running is the RTC and the watchdog.

Could you please confirm whether this is the recommended way of measuring the current.

We have also tried measuring using the PPK as a ammeter, and connecting it to the measurement pin (p22) while using the USB as power source, however we are getting even higher readings using that method.

Please advise.

Regards,
Frikkie

[JONATHAN LL]

Hi,

Can you provide the PPK2 measurement files?

What SW are you running on the 53DK ? is it one of our samples?


Have you seen this guide:Optimizing Power on nRF5340 SoC Designs - Blogs - Nordic Blog - Nordic DevZone (nordicsemi.com)

Regards,
Jonathan

[Frikkie Badenhorst]

We are using our own custom, baremetal application (no Zephyr). In the application, we only have the RTC, Watchdog 0 and 1 UART enabled and running. 

We have managed to place the device in System Off mode, in which case the system draws 2uA. I think this is expected, so I would believe our above method of measuring current is fine?

JONATHAN LL said:

Have you seen this guide:Optimizing Power on nRF5340 SoC Designs - Blogs - Nordic Blog - Nordic DevZone (nordicsemi.com)

Thanks for referring me to this article, however we have created our own separate project (without a proj.conf file) as we are not going to use Zephyr. We want to have full control over the device and understand exactly in which state it is and when. I thus have a question regarding

CONFIG_LOG=n 
CONFIG_SERIAL=n

and

CONFIG_PM=y

What exactly is serial logging and is it enabled by default? How would one disable it using firmware rather than editing a config file? If you could refer me to where this is written in the manuals, that should also be fine. Also, what is the firmware equivalent of CONFIG_PM=y?

According to the Product Specification, the PMU is automatic, and you can only put the device in on of 3 states, 1) System On low power (which we are trying to achieve), System on constant latency and System off. How does CONFIG_PM=y fit in here?

Regards,

Frikkie

[JONATHAN LL]

Hi Frikkie,

Frikkie Badenhorst said:

We have managed to place the device in System Off mode, in which case the system draws 2uA.

This is correct. 


The CONFIG's should just be a if() check  of the CMakeList.txt, Kconfig and source files so you can check what how it is done in the Kconfig documentation:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/kconfig/CONFIG_LOG.html?highlight=config_log 
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/kconfig/CONFIG_PM.html?highlight=config_pm 
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/kconfig/CONFIG_SERIAL.html?highlight=config_serial#std-kconfig-CONFIG_SERIAL 


Regards,
Jonathan