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2384122_en-US

Difference in ADC noise between BCTU Control Mode and Trigger Mode

Hello,

I am working on an application using the [S32k322] where I use the eMIOS timer to trigger the BCTU every 100 µs to read analog data.

I am observing a strange behavior between the two BCTU modes:

  • Control Mode: When the ADC CTU mode is set to Control Mode, the ADC conversions are completely stable. The data read via FreeMASTER is clean and free of noise or glitches.

  • Trigger Mode: When I switch the ADC CTU mode to Trigger Mode (keeping the 100 µs eMIOS trigger identical), the sampled analog data becomes noisy and exhibits noticeable glitches in FreeMASTER.

Are there specific architectural configurations, timing constraints, or register settings (such as trigger delays, FIFO configurations, or clock synchronization) required for Trigger Mode to prevent this noise?

Thank you for your help.


Output with ADC ctu mode : Trigger Mode

Stark__2-1782126491792.png


Stark__0-1782125656766.png


output with ADC ctu mode : Control Mode

Stark__3-1782126564933.png


Stark__1-1782125738057.png






Re: Difference in ADC noise between BCTU Control Mode and Trigger Mode

Hi@Stark_

could you please share the test project and i will test it on myside.

Re: Difference in ADC noise between BCTU Control Mode and Trigger Mode

Hi @Senlent ,

   Thanks for the response. My ADC clock is 160MHz, and I've attached my ADC configuration and register values below.

Clock

Stark__1-1782196451195.png


ADC Configuration

Stark__2-1782196500638.png

Stark__4-1782196672188.png


Output with ADC ctu mode : Trigger Mode

Stark__3-1782196552394.png


output with ADC ctu mode : Control Mode

Stark__5-1782196875804.png


Re: Difference in ADC noise between BCTU Control Mode and Trigger Mode

Hi@Stark_

Based on the configuration screenshot you provided, there are some configuration issues, specifically the division ratios for the module clock and calibration clock.

The ADC clock configuration must strictly follow the table below.

Senlent_0-1782179202962.png

please change it and test  again,

Re: Difference in ADC noise between BCTU Control Mode and Trigger Mode

Hi @Senlent 

I have attached test code.
is it possible to work on BCTU and normal conversion for the some selected channels (ADC_Instance0 and ADC_Instance1)?

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