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Default Value of P1OUT

Mr.Nischay Kumar V
Intellectual 505 points

 

Hello forum,

Most of the Control Registers & SFRs on the MPS430 are default to 0 after power up but the user's guide states the default  PUC state as "unchanged" for P1OUT and P1IES registers. i am unable to get what's meant by   "unchanged". Also would like to know the default value of  P1OUT on power up


Regards,

Nischay

  • 0
    Expert 1385 points

    On power up: garbage. This is not a problem since P1DIR defaults as inputs.

    On reset (assuming power stays up): the value it had before the reset occurred. The value is "unchanged".

     

    I'm being rather generic on the definition of what a "reset" is. Please review the user's guide to learn more about PUC vs. POR vs. BOR if there is any question.

  • 0
    Guru 227245 points

    PxOUT and PxIES are not initialized on a PUC because it is not necessary.
    The default direction is input (and on the chips with pullups, these are disabled), so the value of PxOUT is a don't care.
    Same for the PxIES. Edge interrupts are disabled after a PUC, so the trigger edge of these disabled edge interrupts is a don't care too.

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