[dorkbotpdx-blabber] Xilinx

Thu Dec 18 13:20:41 EST 2008

Paul, 

I remember using the 2064.  It was a great part.  The part you mentioned
looks good too.  I was wondering about how tolerant the coolrunners were.
The dip module that digilentinc sells is a coolrunner II.  I do remember the
2064 drawing a lot of power.  I was hoping that over the past 20 years they
would have fixed the power consumption problem. (by some other method than
lowering the operating voltage)

Other than Xilinx, what about a 22v10, 16v8 or other smaller device?  I've
used them in the past but if I remember right, programming them was much
more of a pain and the possibility of in-circuit programming goes away
completely.

- greg

-----Original Message-----
From: dorkbotpdx-blabber-bounces at dorkbot.org
[mailto:dorkbotpdx-blabber-bounces at dorkbot.org] On Behalf Of Paul Stoffregen
Sent: Thursday, December 18, 2008 2:15 AM
To: A discussion list for dorkbot-pdx (portland, or)
Subject: Re: [dorkbotpdx-blabber] Xilinx

I've used the Xilinx FPGAs and CPLDs several times over the years.... 
starting with the XC2064 FGPA chip back in 1990.  Generally, CPLDs are 
easy and FPGAs are a pain in the ass.

You probably want the XC9500 generation CPLDs, like the XC9536 and 
XC9536XL.  I have used these in a few designs and they work great.  The 
prices on the 3 volt ones are very nice, approx $1 in single qty!  None 
come in DIP package, but they are available in PLCC44 which you put in a 
through-hole socket or a PLCC-DIP adaptor.  Here's a Digikey link.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=122-1570-ND

The one downside to the XC9500 chips is static power consumption.  
Especially the 5 volt parts are major power hogs.  The 3 volt ones are 
better (and 5 volt tolerant), but still they draw steady DC current, 
around 1 mA per macrocell.  The specific current depends on how many 
product terms the software had to use to implement your design, but plan 
on about 1 mA per macrocell you use, and of course much more if you 
clock super fast.

All the CPLDs are flash memory, which is a lot easier than RAM-based 
FPGAs that need to get configured at powerup.  They all are in-system 
programmable via JTAG, and the Xilinx softare can program them via the 
parallel port.  They sell a parallel port cable, which you can easily 
build because they publish the schematic (it's just a couple HC125 
buffers plus resistors and capacitors).

At one time Xilinx also made a XCR3032 "coolrunner" CPLD which came in 
PLCC package and ran at 3 volts with vitually zero static current (like 
all the "coolrunner" chips).  I used it in a few designs and I probably 
have a few left.  Sadly, it seems to be discontinued (look for XPLA3 on 
their site).  It was never nearly as cheap as the XC9536, but the 
super-low current (at "low" clock speeds) was very nice.

The modern coolrunner chips are all 1.8 volt.  You can power the I/O 
pins are 3 volts, but there is no 5 volt tolerance.  They also only come 
in fine pitch surface mount.

The Xilinx ISE software is very nice, and it's free.  Last time I used 
it, they had released a linux version, but it was essentially the 
windows code ported and just running the windows version in vmware was 
still easier (and the parallel cable worked fine via vmware).  You can 
use verilog or vhdl, but for small designs I prefer to just draw a 
schematic, which also works nicely.  Most of the documentation mentions 
a constraints file, but there is a way to attach pin number attributes 
in the schematic so you can just push a button to turn the schematic 
into the jedec output file.

-Paul

Greg Grunest wrote:
> Is anyone on the list working with Xilinx PLD/FPGA devices or any other
> brand or type of field programmable logic devices?
>
>  
>
> Last time I used one was almost 20 years ago and required an expensive
> programmer ($2500) and software.  It looks like they are all JTAG now and
a
> version of the dev software is available for free.   Also, last time I
used
> them, they had small devices (sub 24 macrocells) which I am unable to find
> now.  Everything I could find on their website is massive with 50,000
gates
> minimum up to 570,000 gates and multiple power PC cores in them.  Am I
> missing something?
>
>  
>
> I'm totally open to devices other than Xilinx and any suggestions would be
> appreciated.
>
>  
>
> I'm looking for:
>
>             A small-ish programmable logic device (approx 2000 gates or 20
-
> 40 macrocells)
>
> In a 32 pin or less package (preferably dip)
>
> With free or cheap development tools (that don't suck!)
>
> That programming devices are easily obtainable
>
> The chips themselves are cheap and easy to obtain (don't need no $500
Hughes
> "sea of gates")
>
> In circuit programming would be awesome
>
> A device family with a wide range of devices which use all the same
> programming tools and software
>
> Oh yeah, and A Pony! - (Thanks Mykle!)
>
>  
>
> - greg
>
>  
>
>  
>
>  
>
>
>   
> ------------------------------------------------------------------------
>
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