External Pullups on PORT A


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  1. #1

    Question External Pullups on PORT A

    Howdy

    I am going to be interfacing Port A on a 16F870 to six outputs from a 74LS573 Octal Latch. The outputs from the latch will not be Tri-Stated, only High or Low. I have all the Port A Pins configured as Inputs ( appropriate fuses set, etc). My question is, will I need external Pullups on the Port A pins , since they will never be floating. I think all but one of the Port A pins can be configured with internal pullups, but I would need one anyway, so would just add them to all inputs.

    Ken

  2. #2
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    I would pull them low with maybe a 10K. Sometimes low is not always low enough but high is normally good.
    Dave
    Always wear safety glasses while programming.

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    Thanks Dave

    Actually I have the PCB laid out so I can go either way fairly easily. I'll take the 10K pulldown approach.

    Ken

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