Power Profiler Kit Offset/Miscalibrated?

RE: Power Profiler Kit Offset/Miscalibrated?

Oliver — Sun, 21 May 2017 21:26:21 GMT

With your code above Otii shows 2.38uA https://goo.gl/pebh9P and the PPK software 1.51uA https://goo.gl/fzevhg The Fluke shows 1.6uA-1.7uA. The power switch is on and the three on the PPK are set to DK ;)

BTW: Otii does not recognize the PPK, if the mass storage function of the debug interface is disabled.

RE: Power Profiler Kit Offset/Miscalibrated?

Sigurd — Fri, 19 May 2017 12:59:00 GMT

If you put the chip in system ON sleep mode, what current are you seeing with the different instruments?

You should see about 1.2 µA power consumption.

You can put the chip in system ON sleep mode like this:

int main(void)
{

    while (true)
    {
        // Enter System ON sleep mode
        __WFE();
        __SEV();
        __WFE();
    }
}

Regarding Otii, you should turn on the power switches...:

RE: Power Profiler Kit Offset/Miscalibrated?

Oliver — Fri, 19 May 2017 12:02:05 GMT

It's revision is 1.1.0 (2017.02).

RE: Power Profiler Kit Offset/Miscalibrated?

Sigurd — Fri, 19 May 2017 09:35:55 GMT

What revision of the PPK do you have? Based on experience, we see about max 2-5% inaccuracy worst case. If you see in this blog post here, we measured the difference between PPK and KeySight N6705B to be ~0.056 uA

RE: Power Profiler Kit Offset/Miscalibrated?

Oliver — Fri, 12 May 2017 14:16:52 GMT

Nevertheless I got four different currents for the same SW running: Otii: 3.08 uA PPK: 2.17 uA Agilent: 4.3 uA (last calibration <2yrs) Fluke: 4.9 uA (last calibration ~ 5yrs)

I know that these are very low currents and it's not so easy to get very accurate values, but the error seems still pretty high to me. Do you have any suggestions? Or what current do you expect in idle mode with the code above? My idea is: 0.1uA RTC + 0.25 uA LFXO + 1.5 uA (System ON + full ram retention) = 1,85 uA Do I miss anything? If the BSP LEDs are enabled, is the TWIM in idle?

RE: Power Profiler Kit Offset/Miscalibrated?

Oliver — Fri, 12 May 2017 13:51:52 GMT

Thank! This is a bit embarrassing now; I thought the regulator works for the connected DK as well. Is there any option to measure at different voltages? The only way I see in the schematics is to disconnect the voltage reg. U3 on the DK board and apply an external voltage on P21. But I don't want to cut any traces...

RE: Power Profiler Kit Offset/Miscalibrated?

Sigurd — Fri, 12 May 2017 13:40:43 GMT

But you are measuring on your nRF52-DK? The "Reg" position is used when performing measurements on external/custom hardware via the “DUT” connector. When doing measurement on a DK, the power select should be on "DK".

See page 12 in the PPK User guide.

RE: Power Profiler Kit Offset/Miscalibrated?

Oliver — Fri, 12 May 2017 13:37:12 GMT

Regulator (middle position)

RE: Power Profiler Kit Offset/Miscalibrated?

Sigurd — Fri, 12 May 2017 13:35:55 GMT

In what position do you have the "Power select" switch? Is it set to "DK" ?

RE: Power Profiler Kit Offset/Miscalibrated?

Oliver — Fri, 12 May 2017 12:55:24 GMT

I get different results now. When I change Vdd to 2.4V, the current is even negativ...

PPK with 2.4V: https://goo.gl/H53lHn PPK with 3V: https://goo.gl/T7fJEn

Otii with 2.4V: https://goo.gl/6kOj8w Otii with 3V: https://goo.gl/6rQMir

RE: Power Profiler Kit Offset/Miscalibrated?

Sigurd — Fri, 12 May 2017 11:06:22 GMT

Have you tried using the PPK PC software from Nordic ? Do you get the same result when using the Nordic Software and the Software from Otti? You can download the Nordic PC software for the PPK here