nrf52 saadc current

[yaron]

Hi

I have noticed that the moment I start SAADC task ("nrf_saadc_task_trigger(NRF_SAADC_TASK_START);"), my CPU current consumption rises by 2 mA! (tested with chip version QFAABA / 1542AB, on PCA 10036 board).

according to Product Specification 0.6.3, "ADC current during ACQuisition and CONVersion35 700 µA".

How can that be explained?

Thanks Yaron

[MartinBL]

Hi

I believe the extra current you see is the current drawn by the EasyDMA used by the SAADC. EasyDMA draws about 1.2 mA, and added to the 700 uA SAADC current it sums to ~2 mA. Unfortunately the EasyDMA current is not documented anywhere. Nor is the SAADC driver taking it into account and disabling the EasyDMA feature when not needed. The issue is reported internally and a workaround will be available in the final release of SDK V11.0.0.

[kirkus]

Any updates on this issue? I'm using Rev 1 silicon, release SDK 11.0.0 and release SoftDevice 132 2.0.0 and I'm seeing a constant 2 mA draw as soon as I do nrf_drv_saadc_sample_convert(). I'm only calling it once every minute or so, but it never drops down after that first call.

EDIT: Never mind, saw the answer on another question.