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CCS/UCD3138: I don't understand PEC_VALID of UCD3138 ?

user5006419
Expert 1795 points
Part Number: UCD3138

Tool/software: Code Composer Studio

I find the register of PEC_VALID :

PEC Valid Indicator
0 = Received PEC not valid (if EOM is asserted)
1 = Received PEC is valid 

the meaning is when received wrong PEC , the PEC_VALID is Low ;when received right PEC , the PEC_VALID is Hi ?

Is PEC verification handled by hardware or software?

The system takes PEC to PSU write byte and no PEC to write word. How is the hardware distinguished?

;

  • 0
    TI__Genius 17090 points

    The PEC verification is handled by hardware.  I don't understand the last question where the write byte has a PEC, but the write word doesn't.  Normally the PEC is always used or always not used.  If the PEC is optional, the software can handle it.  The PEC VALID bit will be set to indicate if the PEC is valid, but the software can decide whether to use it or not.  The PEC VALID bit doesn't have any effect on how the hardware handles the data.  It's just a hardware indication whether the PEC is valid or not. 

  • 0 in reply to Ian Bower
    Expert 1795 points

    from the picture , I find no PEC , Why the PEC_VALID is also to be High ( Write 2 Bytes with no PEC )? 

  • 0 in reply to user5006419
    TI__Genius 17090 points

    That's my mistake writing the document.  PEC_VALID should not be going high there.