Saadc

[Andrea Rossi]

Hi,

I'm using the saadc and I notice that the max value that saadc can convert is 3,3V. If I try to convert an higher value, the result has no sense. For my project, I need to convert value of max 5 V.

Is it possible with nRF52832?

I see that I can change the reference of the saadc with an external reference but I'm not sure how to do it neither if it can solve my problem.

Thanks for helping me.

[ketiljo]

You can measure higher voltages if you use an external voltage divider, like this: https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/measuring-lithium-battery-voltage-with-nrf52

Remember that the voltage on any pin must be lower than VDD+0.3 V.

[Andrea Rossi]

Thanks for this hint.

But is there a possibilities to measure an higher voltage directly with nrf? I'm powering a sensor with 5V, and I would like to know if it is possible to use that 5V source also as external reference for the saadc.

Thanks again

[ketiljo]

No, the ADC can't measure higher voltages than VDD, unless you divide it. 

[Andrea Rossi]

Ok, thanks.

And VDD must be max 3.3V, must it? Or can I use an higher voltage for VDD( so 5V)?

[ketiljo]

VDD is max 3.6 V, please see the documentation: https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/recommended_op_conditions.html#concept_vng_xls_2q

Anything above this _will_ break the device. 

[Andrea Rossi]

Understood.

Thanks again