Interaction JLink and Power Profiler PPKII?

RE: Interaction JLink and Power Profiler PPKII?

Stian Røed Hafskjold — Fri, 10 Dec 2021 08:42:12 GMT

Ok, perfect! I believe you can start out by using the zephyr/samples/basic/blinky example in nRF connect SDK. Just remove all code from main(), and it should stay in system ON idle (2-3 uA). You probably will have to disable all UARTs (logging) as well. Add CONFIG_SERIAL=n to prj.conf to quickly disable all UARTs.

RE: Interaction JLink and Power Profiler PPKII?

androbi — Thu, 09 Dec 2021 18:58:15 GMT

You were right, thank you very much! The JLink provided the missing ground reference, now I get the same results with and without JLink, connecting the PPKII GND. I now get 50uA for idle and 500 uA for advertising. I think the idle value is still too high, but this is probably a problem in my code.The example you mention is an SDK example, is there anything similar available for nRF Connect?

I power the dongle as described in the infocenter using VDD OUT, cutting SB2 and soldering SB1.

RE: Interaction JLink and Power Profiler PPKII?

Stian Røed Hafskjold — Thu, 09 Dec 2021 10:59:49 GMT

OK I see. Are you connecting the CR3032 to the VDD_nRF pin?

The PPK in ampere meter mode should also have a ground reference to the dongle. So connect one of the GND pins on the PPK to the negative side of the battery. I believe this might be the reason for the weird behavior you are seeing. Because when you connect the JLink the ground reference is made through the USB interface to the PPK

RE: Interaction JLink and Power Profiler PPKII?

androbi — Thu, 09 Dec 2021 09:54:51 GMT

Thanx for your answer! The results also seem strange to me! You are right, of course we use SWD for the dongle. So it looks like the Debugger sources current in my case (though I have the Vref pin connected). I will try the example you suggest with the debugger disconnected and post my results here.

In what I have posted so far the USB port was not plugged in, I don't use it at all. Power comes from a CR3032 cell and I have the PPKII in ampere mode, measuring directly what comes out of the cell.

RE: Interaction JLink and Power Profiler PPKII?

Stian Røed Hafskjold — Thu, 09 Dec 2021 09:15:24 GMT

Hi, these results seem a bit strange to me. It's normal to get some leakage current on the SWD interface (nRF uses SWD not Jtag). Whether the current goes up or down depends on the voltage on the JLink. Usually the voltages should be matched using the VRef pin, but I've seen many times that this is not the case and the JLink will either source or sink current. So you should always unplug the debugger before any current measurements, then you don't have to worry about any leakage currents.

The fact that the current rises to 150 uA when then JLink is disconnected is strange. I think you should verify your measurement setup using a FW with a known current consumption. You can start with the ble_app_pwr_profiling example. It starts out in system off and you should see below 1 uA of current draw.

Also please describe your measurement setup. Is the dongle plugged in to the USB port while measuring? The USB interface will often create lots of noise, making the measurements unreliable. Maybe the external debugger is somehow stabilizing this noise?