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TMS320F28388D: Digital Filter for ADC of TMS320F28388D

Biteshnath Tiwari
Prodigy 100 points

Part Number: TMS320F28388D

Hi,

    

I want to implement digital filters for the ADC channels.

 

Do you have any sample code implementation for TI MCU (MPN -  TMS320F28388DZWT) ?

Regards,

Bitesh

  • 0
    TI__Mastermind 41380 points

    Hi Bitesh,

    Can you provide some specifics on what you are trying to accomplish with digital filtering on the ADC channels, this way we may be able to see if there are features on the F28388D that you can use.  There is a ADC PPB (post processing block) unit that is able to act upon the converted digital result and able to take action if low or high thresholds are met or if a zero crossing is detected.  PPB might be an option that you can use.

    Regards,

    Joseph

  • 0 in reply to Joseph Casuga
    Prodigy 100 points

    Hi,

       Thanks for your response.  I'm attaching the image of ADC values plotted. There is a lot of high frequency and high amplitude noise that I want to eliminate.

     

    Can you guide me with some reference code or explanation ? We have stepper motors, solenoid valves and other EMI generation sources, impact of which we want to reduce in the code. 

  • 0 in reply to Biteshnath Tiwari
    TI__Mastermind 41380 points

    Hi Bitesh,

    Can you provide additional details on the input signal being converted:

    1.) What is the frequency of the input signal?

    2.) How fast is the ADC sampling this input signal?

    3.) What is the amplitude of the sharp spikes and are these spikes periodic or do these spikes correspond anything that is switching in the application?

    Regards,

    Joseph

  • 0 in reply to Joseph Casuga
    Prodigy 100 points

    Hi,

        Thanks for taking time and asking questions. Please find the responses below.

    1.) What is the frequency of the input signal?

    Max frequency is 50KHz

    2.) How fast is the ADC sampling this input signal?

    1 MSPS

    3.) What is the amplitude of the sharp spikes and are these spikes periodic or do these spikes correspond anything that is switching in the application?

    Noise is not periodic but superimposing on desired signal with high amplitude. We suspect noise is because of 5 stepper motors and solenoid valves inside the product.

    Regards,

    Bitesh 

  • 0 in reply to Biteshnath Tiwari
    TI__Mastermind 41380 points

    Hi Bitesh,

    There is a Sigma Delta Filter Module (SDFM) in the F28388, however the module is intended for signals below 10KHz so it might not work with the signal that you are sampling in your application.

    Have you tried adding input filter (RC) to attenuate the spikes?  Another option would be to filter the spikes in SW by discarding the min/max values for a group of SOC conversions but processing of the conversion results with software would take a lot of cycles and will affect your control loop time.

    Regards,

    Joseph