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I'm working on a tic tac toe project using logic gates. I'm trying to make it automated.

At one point , my circuit have to get one signal (high) among eight input pin.But there will some case arise when two pin simultaneously give high. But I only want one . So I'm thinking of a buffer circuit which take all the input but give the output only one like priority encoder . I'm looking for an IC which should have same number of input and output pin, but only give output to only one pin . Is there any IC like that.

I don't wanna go to design that cause it may couse my jumbled.

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No, there's no single IC that does exactly that (that I'm aware of), mainly because that isn't a commonly-required function. It's generally much more useful to provide a binary representation of the highest-priority input at the output of a priority encoder.

But you could take such a priority encoder chip, and connect its outputs to a decoder chip (another commonly-available function), and end up with the result you desire.

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You could use a set of NOT gates and AND gates to get the output you desire like so:

schematic

simulate this circuit – Schematic created using CircuitLab

This would make the inputs in decreasing priority, but never more than one would be high.

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  • \$\begingroup\$ This makes the most sense. But if you don't want to wire up lots of AND gates, you can do what Dave Tweed suggests and use a priority encoder (like the 74*148) to get the number of the active input, then feed that to a 3:8 decoder. \$\endgroup\$
    – Tom Carpenter
    Commented Apr 23, 2015 at 13:14
  • \$\begingroup\$ @TomCarpenter: Absolutely right. For my schematic you would need 4 ICs, 2 for the NOT gates (biggest package I can find on digikey.com is 6 gates per IC) and 2 for the AND gates (biggest package is 4 AND gates per IC on digikey.com); Dave Tweed's solution uses just 2 ICs and less wiring \$\endgroup\$
    – Phil B.
    Commented Apr 23, 2015 at 13:17
  • \$\begingroup\$ @PhilB , I also thought that but problem is two high signals will occur at the same time but due to not gate there is some time delay for which an extra noise like signal also occur in output pin which input high is neglected. this will cause problem . \$\endgroup\$
    – Anklon
    Commented Apr 23, 2015 at 14:54
  • \$\begingroup\$ @Anklon - perhaps adding a capacitor to ground on the outputs will help remove those "blips" ? You haven't specified how long the high signals will sustain, so not sure what to work with here .... \$\endgroup\$
    – Phil B.
    Commented Apr 23, 2015 at 16:45

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