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TTL Logic Analyzer Recommendations?

mmruzek

mmruzek

Experienced Member
Joined
Sep 28, 2011
Messages
227
Location
Michigan, USA
Hello, I am working on a homebrew TTL stack computer design using 74LS series chips. I recently created a single board version of the computer with an integral 50 channel bus. My computer is clocked at 1 MHZ. I have made provision for a bus-out connector, anticipating that I might want to hookup a logic analyzer.

Logic analyzers are a whole new ball game for me. I see a mountain of used equipment on EBAY, much of it is priced very reasonably, around $100, etc. Older equipment is A-OK with me, but USB stuff is fine too... if it gets the job done. Looking for guidance and suggestions from those that know! Thanks. Michael
 

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Higher end are the Saleae LA's, but they are pricey. They stream over USB so no sample buffer limit to worry about. The software requires a modern PC with lots of processing power and their USB3 solutions are the best ones.
www.saleae.com

Saleae Logic Analyzers

Effortlessly decode protocols like SPI, I2C, Serial, and many more. Leverage community created analyzers or build your own low-level or high-level protocol analyzer.
www.saleae.com www.saleae.com

A bit long in the tooth is a LogicPort, you can see them here - its big limitation is the number of samples it has memory for (2K), but it does support compression to make that value larger. It captures, then transfers over USB. If you are running on a slower PC, their software is efficient and fast. It will require much more fiddling with triggers to capture what you want as opposed to a Saleae where you capture all the data you want and just go digging through it. You can often find these for a lesser price on eBay if you look. If you download the software and think it is for you (it has a demo mode) and want one, let me know as I might have a 3rd one that I could part with.

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www.pctestinstruments.com

I'll let others chime in about a dedicated LA like the HP ones; I don't have any experience with those. There are also MSO's which have LA capability built in, but I've always found the USB models to be easier to deal with.
 
Haven't bought stuff recently but can give a little info on things to investigate. Name brand older equipment can have better flexability on display and triggering than some of the modern equipment. Old equipment has limited memory depth. Some only stored changes which could make the limited memory more useful. Need to make sure old equipment has all the cables and accessories you need since they can be expensive or difficult to find. Old equipment may be slow if it does have deeper memory and saving and exporting the capture may be slow or require floppies.

I need non TTL levels for some of my stuff which lowest end modern stuff doesn't do. I have HP and Philips old logic analyzers. I have Rigol scope with 16 logic channels and Saleae logic pro 16. If I want to look at address and data bus at once I have to use the older equipment. With your easy hookup provisions I assume you are looking for 64 channels. The Saleae was purchased for analog capture also and capture limit of memory in your host computer. The Rigol user interface is very poor compared to the older equipment and other than convenient for having one small portable unit somewhat disappointed by the purchase of that option. The Saleae was better but neither can do something simple like bus together a set of signals and display as hex and not display the individual signals. For the Saleae a third party plugin may be available to do that. Feature request for this has been in there system for years.
 
Thank You both for that great information! Gives me a good direction to proceed and explore. Much appreciated. Michael
 
Those cheap $10 USB logic analyzers are very useful for troubleshooting. They work great with sigrok PulseView or Saleae Logic. Great way to get started and identify what you need for long term.
 
Last edited:
djg said:
Need to make sure old equipment has all the cables and accessories you need since they can be expensive or difficult to find.
Click to expand...
This is a very important point with old logic analyzers. The prices can look very affordable, but without all the cables, pods and flying lead sets, they are useless.
 
I've seen how this stuff gets disposed of.
The instruments are stacked on a pallet. The cables/pods go in a big box.
The pallets get sold (cheap). Nobody bids on a box of random cables.
They never go the same direction after that.

Sad really.
 
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