Hi,

Are there any chips out there that have all the following on 1 chip?

AND gate
NAND gate
2 AND gates with inverted inputs.

The reason I ask is I need to free up a couple of pins on my PIC chip. I am currently outputing 4 different values on 4 pins. What I want to do is output the 4 different values on 2 pins and use these gates to get the 4 results...i.e.
0 + 0 = 1
0 + 1 = 2
1 + 0 = 3
1 + 1 = 4

NAND is the first, AND with 2nd inverted input is second, AND with first inverted input is third, and AND is fourth.

I suppose I could do it with 2 NOT gates and 4 AND gates.

Cheers,

Craig

 

Funny you should ask...

http://www.electro-tech-online.com/g...es-one-ic.html

 

Quite interesting but I would probably still need a few of these to do the job I want. I would rather do it with 1 extra chip.

 

Then perhaps.
http://www.ee.ctu.edu.tw/material/da...et/16v8mil.pdf

 

Now thats a pretty nice chip! Bit of an over kill for what I'm doing though - it kinds of also leads to the point of why not just by another cheap as PIC chip and program that.

What I am going to do though is remove 6 other pins I used for a 8bit wide bus and instead use a shift register to store this. I will then only need 2 pins to do this.

Thanks for the info though.

 

@Mike: I have not seen any PAL's or GALs for a long time. My HS uses them, but I am going to persuade the teachers and the school board to stop using GALs, as they are completely left behind as compared to microcontrollers.

I would go for the 74xx08 and the 74xx04, as it is small and not a GAL, as then you would have to get a programmer, etc.

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An ISP Gal device eliminates the need for any fancy programmer. Only a PC is needed.

I would like to hear the response you get after making this proposal.

 

Looks like a 74HC238 might do the trick for you:
http://focus.ti.com/lit/ds/symlink/cd74hc138.pdf

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0 + 0 = 1
0 + 1 = 2
1 + 0 = 3
1 + 1 = 4

Heck, that would work. Nice

 

Its middle of summer vacation, so I have some time to wait

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you beat me to it. I just saw the demux chips. I'm going to use the HCF4028 instead though as I want High states.

Cheers,

Craig

 

That's equivalent to a NOR gate, it sounds like you haven't tried to use boolean algebra to simplify your expression.

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If you use a shift register such as:-

http://www.fairchildsemi.com/ds/74/74VHC164.pdf

you can output basically independently on as many outputs you want, using two pins on the PIC. There is some more code to be written and the outputs will go to the wrong state briefly while all the outputs are changing.

 

The 74HC238 will give you active high outputs. The 74HC138 will give active low outputs. The HCF4028 is also a good choice. Have fun.

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