Open source Logic Analyser

Craig Rodgers · 2003-06-27T03:31:27+00:00

Hi all.I have recently found myself in a position as, I'm sure many of you thathave worked with embedded systems have, where a logic analyser would be ofgreat advantage to debugging my projects. I have now come up agains a coupleof situations where my CRO just won't cut it.Unfortunately I am not able to afford a DSD oscilloscope or a commerciallogic analyser. My requirements are much lower then most of the commerciallogic analysers I've come across anyway, I'm looking for something that canhandle a maximum frequency of about 20~40 MHz.I've decided that I'd like to try and make my own, at the moment I'mplanning a modular architecture based around 74F serries logic and a mcu.The plan at the moment is to have a control module that is responsible forinterfacing the capture devices to a computer for display. And have up to 8capture modules (of 8 bits each) that interface to the a 3.3/5V circuitunder test. Also I'd like to try and keep the cost of each module to lessthen $100AUD.I am aware of a design that was published in Elector electronics some monthsago. It was lacking one particular feature that I deem as essential in anylogic analyser. That is the ability to set trigger conditions based on inputconditions, a feature I plan on implementing in my design.Obviously this design is of a "one-off" nature for myself. I feel that thisis the sort of project that would be of interest to many people involved inembedded systems at a hobbyist to semi-professional level. So I amconsidering a open hardware type approach to this project so that otherpeople can partake, and I dare say I can learn something from theexperience.Which brings me to the point of this post. Does anyone know of a goodsourceforge type site for open hardware development. I was aware of but they seem to have disappeared off the face of the internet.Also I was hopping to gauge the level of interest in people, would anybodyin this newsgroup be likely to use such a product if it was developed.RegardsCraig Rodgers

Jun 27, 2003 23 Replies

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me 23 years ago

I'm not sure why all the problems, we've got cheap ($1200) Tek scopes that work great for the engineers in debugging those frequesnecy ranges. Is there a specific problem that you need solved so you can avoid the hassle?

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rickman 23 years ago

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 Ignore the reply address. To email me use the above address with the XY removed. Arius - A Signal Processing Solutions Company Specializing in DSP and FPGA design URL http://www.arius.com 4 King Ave 301-682-7772 Voice Frederick, MD 21701-3110 301-682-7666 FAX

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Geo 23 years ago

Have you looked at the Ant8? - no connection - but I like the sound of it:-

"Ultra-portable - fits in a pocket. Powered from USB port - no additional power supply required

8 Channels, 3072 samples deep 500MHz sampling speed"

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Ok it is $199 but think of how much design time (your hours) you save... Geo

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Chris Quayle 23 years ago

Agreed. I've bought several items of test gear from the US via Ebay in the last year or so, including a 1630G logic analyser (don't laugh :-) with all probes and manual for ~$200. Not the latest and greatest, but more than adequate for the micro and comms stuff i'm doing at the mo. Looks like it had never been used internally. Shipping was around $80, surface and took about 4-5 weeks. Ebay is the first place I look for test gear now and with the $ at an all time low, some of the kit is a real steal, even with the shipping and import duty.

Unless you have a real interest and pressing desire to build your own, would recommend you buy, as you can't build one of the same quality for the price and man hours...

Chris

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