Quick PIC16F874A question


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  1. #1
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    Default Quick PIC16F874A question

    I am looking at this PIC and notice in the pinout description that on PortC, the buffer type is a Schmitt Trigger, but the description classifies it as a digital I/O. I just want to make sure that these pins will work like a TTL for on/off, unlike the 628A where A.4 is an open-drain and requires a pullup resistor.

    I know I've answered my own question, but I just want to be 100% positive.

    Thanks,
    Tony

  2. #2
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    Default Re: Quick PIC16F874A question

    a Schmitt Trigger is a type of input circuit and therefore refers to the input buffers for the port , portc on that chip has no open drain pins .
    porta.4 however is open drain

  3. #3
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    Default Re: Quick PIC16F874A question

    But it will work like a TTL I/O, will it not? The digital I/O comment I am questioning, even though it is a Schmitt trigger.

  4. #4
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    Default Re: Quick PIC16F874A question

    if the chip is powered from a 5 volt supply then as a input device its logic level thresholds will be similar to any ttl device with a Schmitt trigger input stage and therefore be ttl compatible and as a output its drive capability is well within the ttl family fanout range.
    google Schmitt trigger if you don't understand . (Schmitt trigger is a input feature it has no relevance to the output stage at all)

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