saadc sample value

[kunchalaRajesh]

hi team,

i have trying to wrote a code for saadc module in segger 5.40 using nrf52840 controller. whenever i am trying to  increase the Acquisition time  the sampling  value also  increasing. can  i know  the reason why it is  changing.

and i have another query that is  whenever  i try to change the oversampling value from 2x to 256x then the  sampling  value  is decreasing. why it is happening. may i know the reason.

[Jared]

Hi there,

How much is it increasing and decreasing with when you adjust the acquisition time and the oversampling respectively? 

regards

Jared

[kunchalaRajesh]

at default configurations the sample value is 770 but when ever i try to increase  Acquisition time  the sampling  value also  increasing to 870.

at default configurations the sample value is 770 but when ever  i try to change the oversampling value from 2x to 256x then the  sampling  value  is decreasing to 700 like that.

[Jared]

Hi.

1. Are you performing calibration?
2. What kind of signal are you measuring? 
3. Can you repeat the two test but measure a steady voltage from a bench top supply? 
4. Can you repeat the test but use differential mode, and connect the negative pin PSELN to the GND of the bench top supply?

Any changes in how it varies?

regards

Jared