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?"

Re:Ask a better question...

[Rorschach1]

Nothing terribly fancy. Say 16 channels and 50mhz. Much of what I'm doing is SPI bus and only needs a few channels, but I do sometimes find myself needing more than the 8 provided by the BitScope.

Something that could look at a data line and clock line and give me a hex dump of the data would be nice, but I don't really need any more intelligence than that.

You can do your own with a FPGA easy

[xtal]

I jerry rigged something "good enough" awhile back with a Xilinx 4000 series FPGA and a microcontroller. I might clean it up and release it if there's any demand, but it's pretty simple to implement a basic one.. you just need a bunch o latches synced to a clock.

Anything more than 10-20mhz you are going to have to buy something though.. although I never did tests to see how fast or reliable my hacked apparatus was.

Go ebay hunting. Lots of deals on there.

Re:Timing?

[martinde]

> You'll probably only be able to get timing resolution near that of the OS tick interrupt interval, right?

Only if you do it using a hardware resource under control of the OS and do polling. Even the parallel port can generate interrupts to the OS. Add a microcontroller and/or some custom hardware and the OS doesn't come into play except for display.