nRF52832 SAADC's Problem

[yzfy_12345]

HI: 

    MCU: nRF52832                   

    Reference example:  ...\nRF5_SDK_15.3.0_59ac345\examples\ble_peripheral\ble_app_uart\pca10040\s132\arm5_no_packs

                                           ...\nRF5_SDK_15.3.0_59ac345\examples\peripheral\saadc\pca10040\blank\arm5_no_packs

         I Used the SAADC Detect the fixed voltage (0V and 1.5V) ;  then I find that the AD Convert result is OK.

         But when I Used the SAADC Detect the  sine wave (13.56MHz'),  amplitude = 30mV , Peak to Peak value is 60mV;  I Find that the Result  are very different. Offset  about 200mV. 

          I want to know that,  SAADC Is it possible to detect sine waves??? have some problem??

thanks!

     

[Priyanka]

Hi,

It is possible to detect sine waves with SAADC, provided that the SAADC sampling rate is much higher than the frequency of the sine wave.

In your case, the sine wave has a frequency of 13.56Mhz which is much higher than the maximum sampling rate of SAADC. While sampling, it is important to obey the Fundamental Sampling Theorem.

Hope this helps! :)

Regards,

Priyanka