nRF5340DK hardware description and config doc

[Pret]

Hi

I'm trying to run some power profiling with basic BLE apps on nRF5340DK in conjunction with PPKII. Saw several videos in the on-demand webinars section on PPKII and power profiling (with the examples based mostly on nRF9 series DKs and nRF52840DK).

Is there any particular webinar on power profiling with nRF5340DK ? Also, where can I find the documentation on nRF5340DK of the hardware side, in particular the configuration of various switches and a proper setup for PPKII ? (I realize there is a solder jumper to cut off on the PCB of the DK to allow ampermeter mode of the PPKII ? And then to work without PPKII it is required to re-connect that jumper by a resistor ?)

Also, what is the difference in current measurements between using the combo in ampermeter mode and in source mode ? (aside of the obvious fact that the ampermeter just passes the current through the PPKII and the DK is powered on its own, while in Source mode the PPKII powers the DK..)

Is there any practical difference in measuring consumption between ampermeter mode and source mode of the PPKII when the DK aside of the case when the DK is required to be powered by a local battery/Li-Po) ?

Thank you

[Hung Bui]

Hi Alex, 

Both using source and using ampermeter mode should give you the same current consumption if measured correctly. Usually it's easier to measure the current to the nRF chip by using ampermeter than sourcing it because there are chance that you have additional components on the board that draw current. So if you simply measure by sourcing the whole board with the PPK you may measure the current for all components not just the nRF53. 

We had a webinar back in Mar that showed a handson session about using PPKII to measure current consumption on nRF53. You can have a look at the recording here. The demo was from minute 46th. 

[Pret]

Thank you Hung for the response, that helps

I certainly watched your webinar as you mentioned, it was indeed elaborate and helpful so prepared to proceed with measurements exactly as you described there. However, there are few small details that may probably not very clear for me, such as what exactly solder jumper to cut on 5340 EVB.

At last, I apparently figured it from the 5340DK schematic, but still, before touching the board with a knife and a solder, prefer to check exactly the hardware datasheet/handbook of the DK if such exists (usually EVBs of functional ASICs include the description of all switches/jumpers and instructions of what to do with them for various available configurations)

It is also unclear for me why Nordic has chosen to make the board necessary to cut physically the trace instead of just putting another regular jumper to easily control this, Touching PCB with a knife may lead to permanent damage of the board (like if exerting an excessive force while cutting that miniature trace may accidentally penetrate to the internal layers of the PCB damaging the internal routing). Also requires precise tools (like a soldering microscope) and a steady hand to do the job precisely.

Anyway, I guess for amp mode measurement I need to cut that (SB40 as far as I remember) jumper and after measurements are done to recover that by the shorting resistor R64. Am I correct?

Thank you

Alex

[Hung Bui]

Hi Alex, 

Thanks for your feedback. I will report this internally. I think the reason we have the solder bridge was just a design choice, for more stability and maybe easier PCB assembly. 

You can have a look at the documentation of the nRF5340 DK here. It has detailed information on how to prepare the board to measure the current consumption. 

When not measuring the current consumption, you should short P22 with a jumper. 

[Pret]

Thanks a lot Hung. Regarding of how to facilitate the board with no current measurement required - how not just put the R64 in place instead of making a solder bridge on SB40 ?Or by "shorting by a jumper" you meant exactly by R64 ?

To me putting R64 as zero jumper resistor would seem to be cleaner approach (so that if repeated measurements will be needed - just to rise that resistor and afterwards put it back)

[Hung Bui]

Yes you are right. You can use a zero jumper resistor. But that would requires soldering equipment that not all of our customers have. 

The R64 resistor place holder ASAIK was designed so that you can use a voltmeter /oscilloscope to measure the voltage drop on the resistor to calculate the current going through it ( mount a 10Ohm resistor on R64)