SAADC sampling with DMA into buffer on nrf9160

[Vid]

Hi!

My goal is to sample an ADC channel with 10 kHz sampling rate and acquire 2000 samples in one samples acquistion and then return to lowest possible power state. This sampling will occur very intermittently, however this should not be relevant to this issue.

I couldn't find any direct example with similar functionality for nrf9160, so I am opening a new issue in search of a good example of this feature. Should anyone have it available and debugged, please share.

The starting point is the simple ADC example working well on nrf9160 DK: link based on this documentation DMA (easyDMA) is already used and asynchronous operation to call the ADC is shown here link.

Also this appears to be relevant.

How can this be achieved?

Thank you.

[Håkon Alseth]

Hi,

 

With such a high sampling rate, I think you'll have to use the driver directly.

 

You could use nrfx_saadc driver directly by setting this config entry in your prj.conf:

https://github.com/NordicPlayground/fw-nrfconnect-zephyr/blob/master/modules/Kconfig.nordic#L157

 

Then include nrfx_saadc.h into your application, and if you need the saadc irq handler, you can connect the interrupt directly to the handler, similar to how its done here:

https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/nrfx_timed_signal/src/main.c#L130

 

Kind regards,

Håkon