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MSP430F6779A: sometimes the EMDC Library give large accuracy error

TinK
Intellectual 815 points

Part Number: MSP430F6779A

I have issue about sometimes the EMDC give large accuracy error around 16 % around after first time start EMDC (API EMLibGUIApp_Init).
But when stop EMDC and start EMDC again, the accuracy back to normal error below 0.5 %.

Setting:

EMDC Version: Energy Measurement Design Center version 1_30_00_00

Sampling Frequency (Hz): 4096
Oversampling Rate (OSR): 256
SMCLK Frequency (Hz): 25165824
AC Main Frequency (Hz): 60
Number of Voltage Sensors: 1
Number of Current Sensors: 2

Condition:
Supply voltage 240 V, Current 10 A, power factor 0.5, Frequency 60 Hz. 

When: start EMDC EMLibGUIApp_Init

Power error: 16 % 

When: start EMDC EMLibGUIApp_Init,  stop EMDC and then start EMDC EMLibGUIApp_Init

Power error: 0.5% 

Could you recommend us what point should be cause of problem?

  • 0
    TI__Guru 56685 points

    Hello,

    Sorry for the delay in response here. This is not something we have seen before, more than likely it's an issue where previous data is being utilized upon initial startup. Have you run calibration and sorted those value sin flash? have you done a full reset of the device between EMDC start ups?  Do you see this error when running stand alone? 

  • 0 in reply to Jace H
    Intellectual 815 points

    Hi Jace H,

    Thank you for some advice.

    My system stored calibration value in external memory, I have checked that the value in gEmSWConfig and SD24 registers are same between normal (error 0.5 %) and abnormal situation (16%).

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