MSP432P401R: Interference in ADC

Part Number: MSP432P401R

Hello everyone!

I'm try use MSP432 LaunchPad and see some noise (or interference) in ADC output.

I'm interesting in precision results and captured some arrays of results.

On pictures are:

histogram of codes in case internal temperature sensor and internal REF and launchpad alone;

histogram  in case internal temperature sensor and internal REF and launchpad in assemble with custom input buffer PCB ;

histogram  in case internal temperature sensor and external REF and launchpad in assemble with custom input buffer PCB ;

histogram  in case external op amp buffer connected, input on ground and external REF and launchpad in assemble with custom input buffer PCB ;

Are anybody know:

Can this device itself get clean signal like dedicated ADC? (2-3 codes)

Is my problem with LaunchPad and my own PCB ground noises?

Or I must processing (filter, etc) output codes?

Or right way is use dedicated ADC IC, not integrated in MCU?

Thanks!

  • Thank you for sharing this data. I would like to better understand the configuration of the ADC, so if you could provide a summary or even a portion of the source code that would be helpful.

    - Yes, the device itself can get clean signal like a dedicated ADC. Just in terms of the number of datasheet parameters and typical curves we have tried to communicate that this is a very good ADC and you should expect similar if not better performance than a dedicated ADC.

    - The Launchpad is probably not the best method to test analog performance. This board was designed with the launch pad/booster pack ecosystem in mind to allow for a building block approach to bring together different circuits and devices. Since the routing and layout is generic you do not get the benefits of routing and layout techniques you would use for dedicated analog and digital signals. Still there are a number of examples showing various use cases with the ADC and the noise has not been an issue.

    - Post processing can be an effective means to reduce noise.

    - Dedicated ICs have their place. Some applications use dedicated ICs and then pass the digital information across an isolation barrier to the MCU.

    Regards,
    Chris

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  • In reply to Chris Sterzik:

    Thanks, Chris!
    Code is the compilation from examples, except I'm use timer32, not timer_a for sampling interrupt.
    Buffer is ina159, ref is REF3333. MSP432 part is battery powered.
    I am glad listen what this MCU have good ADC itself and I try make PCB for better results, although I doubt what I can trace 8+ channels better than on LaunchPad.
    Regards, Iurii.