SPIS consumption

RE: SPIS consumption

Stian Røed Hafskjold — Fri, 14 Jun 2019 11:06:52 GMT

Sorry, but it's a symptom of this errata: https://infocenter.nordicsemi.com/index.jsp?topic=%2Ferrata_nRF52832_Rev2%2FERR%2FnRF52832%2FRev2%2Flatest%2Fanomaly_832_97.html&anchor=anomaly_832_97

You can use SPIS as intended, but then you need to accept the additional ~6uA. If that's unacceptable, you can try to use the PORT event instead.

So yes, trigger on PORT event with the CSN line, then enable SPIS, and disable it after it's done.

RE: SPIS consumption

agusuyu — Thu, 13 Jun 2019 14:34:02 GMT

So I can't leave the SPIS enabled and use the interrupt? That's basically not using it as intended.

I'd need a PORT event, then enable SPIS and wait for its interrupt, and then disable it. Is that it?

From the spec GPIOTE shouldn't draw that much current, or should it?

RE: SPIS consumption

Stian Røed Hafskjold — Thu, 13 Jun 2019 13:38:05 GMT

Hi, When the SPIS is waiting for an interrupt in the CS pin, the power consumption is similar to the GPIOTE IN event. You can try to trigger on the GPIOTE PORT event instead, and enable the slave in the interrupt handler.

RE: SPIS consumption

agusuyu — Wed, 12 Jun 2019 12:59:44 GMT

Does anyone see the same thing?

My latest test was to check if it's the "interrupt" on CS.

I'm trying with the example pin_change_int and I get the same current consumption. Could this be it? Even though according to the spec it should be <1uA.

RE: SPIS consumption

agusuyu — Tue, 11 Jun 2019 20:39:07 GMT

Does anyone see the same thing?

My latest test was to check if it's the "interrupt" on CS.

I'm trying with the example pin_change_int and I get the same current consumption. Could this be it? Even though according to the spec it should be <1uA.

RE: SPIS consumption

agusuyu — Fri, 07 Jun 2019 17:40:53 GMT

In trying to figure out what's happening I switched from SPIS to SPIM and I don't have the extra 7uA.

All measurements from a DK (PCA10040) give exact same results using SDK examples (without CONSTLAT).

I can't find anything that would explain this other than it's just what it draws and the 1uA from the spec is wrong. Could that be the case?

RE: SPIS consumption

agusuyu — Mon, 03 Jun 2019 19:50:10 GMT

I'm attaching images of current measurement.

The first one is with SPI Disabled, the second Enabled. The difference is ~7uA.