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Sci.Electronics.Basics -> Magnitude Comparators
There are 3 messages in this thread.
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Author: MichaelDate: 05:40 07-12-07
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Hi,
I'm working on a school project where I need to compare 16bits (4 BCD
values) from a CMOS logic system and need alternative ways of doing it.
So far I've got 4 cascaded 4063 bit comparators, ADC conversion but I'm
struggling for a third. Can anyone suggest a method?
I was thinking about using a CMOS compatible 74 series bit comparator but
it's not really that different from the 4063 method......
Cheers,
Michael
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Author: Stephen J. RushDate: 05:52 07-12-07
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On Fri, 07 Dec 2007 10:40:15 +0000, Michael wrote:
> Hi,
>
> I'm working on a school project where I need to compare 16bits (4 BCD
> values) from a CMOS logic system and need alternative ways of doing it.
>
> So far I've got 4 cascaded 4063 bit comparators, ADC conversion but I'm
> struggling for a third. Can anyone suggest a method?
>
> I was thinking about using a CMOS compatible 74 series bit comparator
> but it's not really that different from the 4063 method......
A microcontroller running a short loop? Some of the Atmel 8-bit
microcontrollers are absurdly cheap.
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Author: ChrisDate: 06:48 07-12-07
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On Dec 7, 4:40 am, "Michael" <mQiQcQhQaQe...@QmQhQiQmQsQ.QcQoQ.QuQkQ>
wrote:
> Hi,
>
> I'm working on a school project where I need to compare 16bits (4 BCD
> values) from a CMOS logic system and need alternative ways of doing it.
>
> So far I've got 4 cascaded 4063 bit comparators, ADC conversion but I'm
> struggling for a third. Can anyone suggest a method?
>
> I was thinking about using a CMOS compatible 74 series bit comparator but
> it's not really that different from the 4063 method......
>
> Cheers,
>
> Michael
Hi, Michael. You might get some homework points for variety by
latching the two 16-bit numbers into shift registers, then serially
comparing the bits, starting with the most significant. First non-
equal (discrete logic here) sets the greater-than or less than flip-
flop. which locks the other one out. Both flip flops reset on the
latch signal.
If it were an 8 X 8 or even a 12 X 12 compare you could use one PROM.
You might offer a suggestion that you could compare the first byte
using a PROM, then if equal, compare the second byte using the same
PROM or a second PROM if you want to stay away from latching and
sequential logic.
Someone else has mentioned using a PIC, which is a valid one-chip
solution.
Not too many ways to compare two numbers except to compare them, I
guess.
Good luck
Chris
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