Determine deep sleep versus awake time in nRF52840 via pin output

[Johan]

Hi!

We are debugging low power in our custom board which has several chips (nrff52840, nrf9160, acc, fuelgauge, pmic, etc etc).

We are seeing strange random increases in current in area of 100uA and also +700uA and sometimes +2mA etc.

To determine the source of this, we need to pinpoint better when nrf52 is sleeping versus is awake.

How can we do that?

If we could see a signal on a pin (set to low), before it's going to sleep, and when waking up, seeing the signal go high, that would help immensely.

We are using nRF connect (zephyr) 1.5.1 currently.

Any help on how to debug this with 52-state?

BR,

Johan

[Simonr]

Hi Johan

I would think this is the devices being in refresh mode which charges a capacitor every now and then that will result in spikes like this. But without seeing the current consumption graph it's hard to say exactly. How do you measure the current consumption (what tool do you use for measuring) and what is the average current consumption you see? 

 The frequency depends on the current being drawn on the regulator output. In system OFF mode the refresh interval is at 100-150 ms, and in system ON idle mode it's at 30-50 ms, typically.

The current consumed during refresh mode is documented here.

Note that the numbers in the PS are typical numbers only, and there will be device to device variations.

Best regards,

Simon