Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

RE: Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

ovrebekk — Fri, 26 Jan 2018 15:37:06 GMT

You can also disable the SoftDevice, if using system OFF is not an option. Then it won't schedule any clock calibration.

RE: Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

AmbystomaLabs — Wed, 24 Jan 2018 17:23:33 GMT

Then look over the following blog entry. You will need to do an SD system power off. Here is the link: devzone.nordicsemi.com/.../

RE: Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

koniho — Wed, 24 Jan 2018 17:01:26 GMT

Yes - the current behavior for the device should be just to wake up from button press via GIOTE event. We should be able to guarantee that when the device has gone to sleep that BLE core will be inactive.

RE: Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

AmbystomaLabs — Wed, 24 Jan 2018 15:27:10 GMT

I think the only way to avoid the cal is to do a system power off or maybe a sd disable. Doing a WFE as you are doing is just holding it up until the next event comes through. The scheduled rtc cal is one of those events. And the ble core still needs to have an accurate clock for beacons, wakeup to listen events, etc. basically whatever you have told the ble core to do.

Are you trying to do a deep sleep with wakeup on a button? Exactly how were you planning to wake up the processor?

RE: Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

koniho — Wed, 24 Jan 2018 00:09:18 GMT

If BLE is not required while the system is sleeping - can the LFCLK be disabled? or will having the SD present always require the LFCLK to be active?

RE: Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

AmbystomaLabs — Tue, 23 Jan 2018 23:27:55 GMT

If you read through the SD spec, it discusses the periodic calibration of the LF_INT. The calibration is required to meet the BLE spec of 250ppm with the internal RC based RTC. The period of the calibration interval is configurable in the RTC config struct.

The RTC is the main clock when the system is asleep and for BLE it needs to be +/-250ppm all the time, thus the requirement to cal it against the HF_EXT.

The normal cal interval is around 17msec every 4 sec. Your plot looks consistent with it.

Here is more info on it: devzone.nordicsemi.com/.../

RE: Periodic (~4s) current blip in Low Power mode NRF52832 SDK V12.3

Matt — Tue, 23 Jan 2018 23:07:56 GMT

Same test result if you disable ALL the other peripherals?