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CCS/MSP430F6779A: calibrate the emeter

Arunraj K
Prodigy 135 points
Part Number: MSP430F6779A

Tool/software: Code Composer Studio

Hi,

I am implementing E-meter with reference of slaa577. library. it is developed by using IAR butt i try implement it in CCS. now i  need to give the calibration values without using calibration GUI. how can i give that calibration values in e-meter project?

  • 0
    TI__Mastermind 49692 points

    Hello Arunraj,

    Thank you for providing the part number and specifying which document (SLAA577) that you've been referring to.

    You can update the calibration values by modifying them in the 'emeter-3ph-neutral-6779(A).h' found in the "slaa577g" -> "slaa577g" -> "MSP430F6779A" -> "Source" -> "emeter-ng" folder. After changing these values to those found in the GUI after you calibrated the device, you'll need to rebuild all the projects.

    Otherwise, if you have a host processor, you'll have to send the proper commands in the DLT645 format to the MSP430F6779A to set the calibration factors.

    Hopefully this helps.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to James Evans
    Prodigy 135 points

    Hi James,

    Thanks you for reply. i find that default macros in the above mentioned file. May i know how to calculate that calibration factors.  please provide some suggestion.

  • 0 in reply to James Evans
    Prodigy 135 points
    Hi James,

    In that above mentioned E-meter library, the current( I ) samples are stored in to 32 bit buffer( they are taking values from SD24BMEML as well as SD24BMEMH) but the voltage(V) samples is store in to 16 bit buffer (only taking in SD24BMEMH). why they are current samples as 32 bit and voltage samples as 16 bit? could be please explain this storage process.
  • 0 in reply to Arunraj K
    TI__Mastermind 49692 points
    Hello Arunraj,

    It's best to have a higher resolution for the RMS current samples than the RMS voltage samples. If I remember correctly, the resolution for the RMS current is down to microAmps (uA) which allows the meter to detect very small changes in current consumption which translates into more accurate measurements of power and energy consumption.

    The 24-bit result for the RMS current won't fit in a 16-bit buffer, so a 32-bit buffer is used. Hopefully this makes sense.

    Regards,

    James

    MSP Customer Applications

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