Open Source Logic Analyzers?

Rorschach1 asks: "I'm a hardware hacker, doing my part to develop useful open source projects, but my projects are getting more ambitious and my test equipment just isn't keeping up. PC based oscilloscopes have been discussed here before, but I'm particularly in need of a logic analyzer. The BitScope does offer an 8-channel analyzer with Linux support, but that hardly compares to most commercial offerings. I'm also concerned by the fact that I can't find any independent reviews of the device, and I'm hesitant to shell out $500 without knowing what I'm getting into. A logic analyzer is a pretty simple device. My current setup runs on a dedicated 486 with ancient DOS-based software. Surely there must be a more modern option available that'll work under Linux, but so far I've been able to find nothing. Perhaps someone can point me in the right direction?"

found via google

[Anonymous Coward]

http://et.nmsu.edu/~etti/winter97/computers/logic/ logic.html [nmsu.edu]

Look at this project...

[stienman]

Take a PIC microcontroller, add a Xilinx fpga, and a few misc other items and you have a decent logic analyzer [dyndns.org].

Check out his Carmon project if you're interested in long term GPS data tracking (stores a GPS data stream to a compact flash card)

-Adam

On a semi-related note

[martinde]

I know this is not what you asked and is probably out of most hobbiest budgets, but I'll mention it anyways as it could help someone. A project we did here absolutely required a scope, and we considered a logic analyzer as highly desirable but not strictly necessary. We had a budget of around $5k - significant but not really that big when you start pricing this stuff.

It had been a while since I shopped for this stuff and I happily found that Agilent (used to be HP) has what they call "mixed signal scopes". Specifically, we purchased a 54622D. It's 100MHz 2 channel oscillscope, but then it's also got a 16 channel logic analyzer built in. (See full specs here [testequity.com].) We purchased it used for around $2600. To get that price we had to play two of the used dealers against each other a little bit. We have been really happy with it so far. $2600 is quite a bit more than $500, but you do get both a scope and a small logic analyzer for that... It's got a built in serial interface and floppy, and it's more portable than dragging a computer around. Take care, and good luck with your quest!

I thought these sounded pretty cool...

[John Miles]

... when their designer announced them on the sci.electronics newsgroups. Unfortunately the control software is not open-source, but he might be persuaded to release the interface specs if someone volunteered to do a Linux port.

http://www.rockylogic.com/products/ant16.html [rockylogic.com]

HP 1631D

[dfranks]

You might want to get something off the shelf instead of investing lots of time in building something. I purchased an HP 1631D for around $120, they seem to be going for around $200 on ebay now. This scope gives you 43 channels (can mix between state and timing with a few predefined setups) and 2 channels of 20mhz analog.

The oscilloscope channels have limited voltage swings, but are good enough for most of the work I have done. You can always build/purchase dividers to measure higher voltages.

If you do get a 1631 or something similar, make sure it has the pods and test clips. They get pretty expensive to purchase/replace.

Dean

Cheapest Logic Analyzer? Heh, got you all beat!

[rfmobile]

With some level shifting circuitry you can turn any common RS232 serial port into a 4 channel logic analyzer. It you've got +5 volt TTL levels, you can probably get away without any extra circuitry.

Say what?!

Yep. Most anyone can do this. In my case, I went so far as to write a device driver that makes it work under Windows NT/2K/XP. It hooks the serial ports interrupt service routine and logs the state of the UART's modem status register or MSR. Four bits from the MSR tell us the state of the CTS, DCD, DST, and RI input pins. I use the RDTSC instruction which offers ridiculous accuracy (theoretically, it's the CPU's clock speed) compared to most other software based solutions - even betten than some coarse-grained hardware solutions.

The same could easily be done under Linux or anything with a serial port and Pentium compatible processor.

I never thought anyone would be interested so no website or anything. Interested persons can send me an email ...

mailto:[e-mail]

-rick