Open source Logic Analyser

[rickman]

mk wrote:

Hello Craig (and all),

I think it may be easier (and cheaper if you only count the cost of the
bits) than some of the replies so far suggest.

Use a Xilinx Coolrunner like XCR3128 (XPLA3 series) becuase these have 5V
tolerant inputs. The latest CoolRunner2 parts are not 5V tolerant.

The Xilinx Webpack software is not crippled at all (for these chips) and is
free. You can get details of what you need in the parallel port programmer
from the web or archives of this group and the build cost is a few $.

You can clock the CoolRunner at 50MHz easily. Put it (and the memory) in the
probe (which will help your skew problems).

Of course if you value your time at a typical business rate its better to go
out and buy a TEK or Agilent machine new but if you want fun this should
keep you amused for ages.

Good luck.

On the Coolrunner parts you need to be aware that the chips are only "4
volt tolerant" until power is applied. I don't know how robust these
parts will be considering that they don't really stand up to 5 volt
signals when not powered. You might be better off with a part with true
5 volt tolerance like the SpartanXL (I think) or the ACEX 1K. From the
ACEX data sheet, "Signals can be driven into ACEX 1K devices before and
during power up without damaging the device. Additionally, ACEX 1K
devices do not drive out during power up."

--

Rick "rickman" Collins

rick.collins@XYarius.com
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[David L. Jones]

On Fri, 27 Jun 2003 21:16:41 +1000, "Alex Gibson" <alxx@ihug.com.au>
wrote:

could probably do a decent speed analyser or scope using a high speed
adc as the front end.cpld or fpga as the backend.

even one of the new cygnal 8051's with 1Mbit adc
(not cheap around US$50 each)
http://www.cygnal.com/products/C8051F060.htm
http://www.cygnal.com/products/C8051F061.htm
http://www.cygnal.com/products/C8051F062.htm
http://www.cygnal.com/products/C8051F063.htm
http://www.cygnal.com/products/productguide.asp

Crikey, you get a lot for your $50 though!

Dave what would you recommend (as you know a lot more on analog than me)
for a good high speed adc ?

I've been working on the low speed 24bit end these day, so haven't
been keeping up to date.
But for a low cost scope front end though, it's hard to beat the
TLC5540. Cheap, readily available (until it goes tits up like all the
others over the years), and good enough for a very useful 8bit scope.

Dave
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