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AM3352: ADC usage in high noise environment

Barend Ungrodt
Intellectual 1420 points
Part Number: AM3352

Hi Sitara Team,

My customer needs to accommodate for a high noise environment, but is having some issues understanding how to take the ADC driver provided by us and do oversampling, front-end digital filtering, and controlling the sample rate and sample periods to using the ADC on our AM3352 running Lynx.

To us it seems that the Sitara ADC Lynx driver options are either a single shot or a continuous read mode.  In continuous read mode, their F/W team confirms if the ADC output file is not read in time the data output file overflows.  In single shot, the Lynx can gather 1 value every 10ms, and what the EVSE system provide can vary 2 to 1 in Voltage measured.

They are asking for help with these drivers in order to harden against the severe noise seen during EV charging. Can we possibly provide them with information on what F/W enhancements can be added at the driver level, that will help their Lynx embedded solutions?

Thanks!
Barend

  • 0
    TI__Guru** 100660 points
    Hello Barend,

    What is Lynx? What version of Linux Processor SDK is the customer running?

    Regards,
    Nick
  • 0 in reply to Nick Saulnier
    TI__Intellectual 1420 points

    Hi Nick,

    Lynx is a "deterministic, hard real-time operating system that provides POSIX-conformant APIs in a small-footprint embedded kernel". However, the software in question is our ADC driver, not the OS. They are looking for more documentation/support on the ADC driver provided by TI that will allow them to do oversampling, front-end digital filtering, and controlling the sample rate and sample periods to using the ADC. Unfortunately, the only documentation we can find are the comments in the code, and this driver guide, and we are hoping that someone more knowledgeable about this driver than us can assist!

    Thanks,
    Barend

  • 0 in reply to Barend Ungrodt
    TI__Guru** 100660 points

    Hello Barend,

    TI supports neither the Lynx OS, nor porting Linux drivers to Lynx. However, I can assist with the Linux ADC driver itself. Where did you get your driver from? Drivers change over time, so I need a Linux kernel version to make sure that we are looking at the same ADC Linux driver. It is also helpful to know if the driver is from a TI Processor SDK (which we support), or from elsewhere (probably not supported).

    Regards,

    Nick

  • 0 in reply to Barend Ungrodt
    TI__Guru** 100660 points

    Hello Barend,

    I'm marking this closed, please respond if the customer has questions.

    In general, it looks like there is an oversampling feature in the Linux TSC-ADC driver, and you can change OpenDelay and SampleDelay values to reduce the sample rate from its 200kHz max. If the customers are worried that VDDA/VSSA are too noisy to allow the ADC to provide accurate measurements, SEL_RFP and SEL_RFM can be used to select cleaner power sources.

    Regards,
    Nick