S32K148 ADC test value unstable

[shaun_yue]

Hi Community,

When using Example"adc_swtrigger_s32k148" project to use ADC module collect the target value ,  found that the test value was unstable. The test results are shown in the figure, which is the same for all three circuits tested.

Test environment： 3.3V supply voltage, target sampling voltage is 3V

Please give some advice

[danielmartynek]

Hi @shaun_yue,

Please try using either a longer sample time or reduce the ADC frequency or use a low-resistance input source.

The ADC must be calibrated.

Thank you,

BR, Daniel

[shaun_yue]

Daniel，

Thank you for  prompt reply. I'll try the advice you gave me. 

About the placement of calibration functions （ADC_DRV_AutoCalibration），whether the function is placed in front of the "while(1)"  or in the "while(1)"  ，which one is placed correctly. 

[danielmartynek]

Hi @shaun_yue,

AN12217 S32K1xx ADC guidelines, spec and configuration

3. Best practices to increase accuracy

https://www.nxp.com/docs/en/application-note/AN12217.pdf

Regards,

Daniel

[shaun_yue]

Thank you for help

last question,  I change the "useroffset"&"usergain" ， and the result no change. And how to use the function ADC_DRV_ConfigUserCalibration .