Problem after restarting SAADC

RE: Problem after restarting SAADC

JoEi — Thu, 11 Aug 2022 07:41:33 GMT

Hi Einar,

thanks the workaround works like a charm. =)

Best regards,
Johannes

RE: Problem after restarting SAADC

Einar Thorsrud — Thu, 11 Aug 2022 07:25:10 GMT

Hi,

I cannot say exactly why this is, but there are a few issues with the SAADC that could potentially play a part. You could try to look at saadc_anomaly_212_workaround_apply() from modules/hal/nordic/nrfx/drivers/src/nrfx_saadc.c in SDK 17.1.0 and consider doing something like this when uniniting the SAADC driver. That will effectively reset the SAADC peripheral.

RE: Problem after restarting SAADC

JoEi — Wed, 10 Aug 2022 12:53:36 GMT

Ok in newer SDK versions this problem is fixed within the nrf_drv_saadc_init function.

Anyhow after some testing I made a peculiar discovery regarding unitialising the SAADC.
So far I've configured the SAADC with NRF_SAADC_OVERSAMLE_4X and 2 channels with burst mode active.
After unitialising the SAADC I have a power consumption somewhere of the neighbourhood of 790µA.
If I configure the SAADC without oversampling and the channels without burst mode after unitialising the SAADC I get a power consumption around 150µA.

Does anyone have an idea why there is such a difference?