[sdiy] 8 bit up/down counter?

[Matthew Smith]

Quoth David Moylan at 18/07/11 05:33...
> Anyone know of a current production 8 bit (or more) up/down counter 
> preferably in DIP?  I need to stack a few of them so would prefer not to 
> have to use 4-bit units.

How many stages do you want to end up with?

If it were me, I'd be looking at programmable logic. One CPLD could give 
you lots of stages.  If you don't specifically want DIP and just want 
non-SMD, a PLCC package in a through-hole socket could do the job for you.

I'm assuming (possibly incorrectly) that, when you ask for current 
production, you're looking to make a number of these and want reliable 
supply.

Only slight caveat with CPLDs is that there is a move away from 5V parts 
(at least with the Xilinx ones I use) to 3.3V. Whilst some of these have 
5V-tolerant IO, they would need a supply regulator if the rest of your 
logic is 5V.  I've noted that the 5V XC95xx parts are starting to go UP 
in price whilst, at the other end of things, I picked up 5 x XC95144XL 
(144 pin QFP, 3.3V) for $18 USD delivered on eBay yesterday.

If you need more stages (say, 64,) than will fit in a regular PLCC 
device, there is always QFP. They really aren't that hard to 
drag-solder. (Could even have a SIP-mounted QFP on its own tiny little 
board with regulator to plug into a row of 0.1" pitch holes/socket.)

I'd be more than happy to write the couple of dozen lines of Verilog 
required to implement something like this on a CPLD :-)

Cheers

M

-- 
Matthew Smith

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