SAADC enable and disable with SDK 15.3 for very low power optimization

[Jean-marie]

Hi to all,

Happy New Year 2020 !

I have developped an application with the nRF52832 ( nRF52DK ) and I use the SAADC for battery level every 2 hours ( no need of precision )

So between 2 sensing I need to uninit the SAADC.

I have read a lot of usercase about the same problem but don't find a real solution.

Is someone can help me with a working example ?

Best regards,  Jiemde

[haakonsh]

There's a 'low_power' mode in the SAADC driver in SDK15.3 and SDK16 that should take care of the power issues. 

Uninitializing should be as easy as calling nrfx_saadc_uninit after you taken your samples.

[Jean-marie]

Hi Haakonsh, Thanks for rapid answer.

I suppose that just before taking the sample you use nrfx_saadc_init() ?

Is the initial init of the SAADC still remain the same and declared in the main  with the function saadc_init() ? 

Jiemde

[haakonsh]

Yes, you need to init the driver before sampling. 

Are you actually having power consumption issues with the SAADC? 

[Jean-marie]

Unfortunately I don't yet receive the power module NRF6707 ( not in stock at Mouser ) and order it in China!

So at this time I cannot tell you with precision the power consumption.

A new VARTA CR2032 coin cell battery is working for about 3,5 days ! so by simple calculation: 0,22 Ah/ 84 = 0,0026 A ) !

Question: In my application I use for example " nrf_drv_saadc_init(NULL, saadc_event_handler); " , must I change it by         " nrfx_saadc_init(NULL, saadc_event_handler); ?

Jiemde

[haakonsh]

Then you should not worry about the issue, the low power mode of the SAADC driver in SDK16 should fix it.