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Richard Erlacher
03/09/13 14:48
  03/09/13 14:55

Read: 987 times
Denver, Co

#189558 - the bandwidth is VERY limited for today's MCU's
Responding to: Andy Neil's previous message
MCU users should be aware that if their MCU is running at a higher rate than 6.25 MHz (half the 16-channel sample rate) fewer channels are available. 16 channels can present quite a limitation. Everyone with whom I've interacted in this context over the past 25 years has regretted low bandwidth and bandwidth vs. channel width/sample depth tradeoffs and other aspects of the ways in which the various mfg's of low-cost LA's tend to make their instruments look good. It's pretty cheap buying an older used HP, Tektronix, or other major U.S. made logic analyzer. I still use my 1980's generation TEK 1240, which has only one 100 MHz card and 4 16-channel 50 MHz cards from time to time, despite the fact I have a much more capable but much less portable analyzer on hand.

There are very good low-end analyzers available on eBay, most of which are fully functional, though it's often difficult to find all the necessary components, e.g. probe pods, lead sets, loopback cables (much more important than you might think!) funtional plug-ins, e.g. serial port, etc.) I generally only buy (for myself, friends, colleagues, clients) instruments that are equipped exactly as I want, so there won't be any "pointing down the wire" when something doesn't work. However, once I've got a fully functional main "box" I can verify the functionality of internal components, e.g. sample memories, GPIB modules, etc. and external plug-ins such as cables, pods, lead sets, etc. All it requires is patience when buying. Here's an example of a very good main unit. It even has the external printer port included.

I know this to be a decent unit, as I know the guy who designed it and subsequently sold his product line to Tektronix, as it outperformed the comparable but more costly unit TEK offered. He subsequently bought a Ferrari and retired, actually a few years earlier than I, though he and I are of about the same vintage. Using the purchase price "for seed" and combined with a bit of patience, one can acquire the remaining pieces such as cables, pods, etc. and end up with a good workhorse.

HP and Tek generally had competing systems and each was a reliable workhorse. I had some experience with the HP 1630 series, back in the days when air was clean and sex was dirty, and found it had some very handy features, e.g. plotting a display of parallel output, say, to a DAC, which happened to be my application of it.

There are many used, old but still useful logic analyzers availalble at very reasonable prices, and not all of them are from HP/Agilent or Tektronix. Shipping the mainframe can cost quite a bit. I'd buy one of these old-timers before I'd buy a "gadget" like the subject.


List of 5 messages in thread
a nifty little logic analyzer      Erik Malund      03/08/13 11:12      
   Previously, on      Andy Neil      03/09/13 01:32      
      the bandwidth is VERY limited for today's MCU's      Richard Erlacher      03/09/13 14:48      
         Hardly ever use a LA dispite working with PLD's and MCU's      Jason Arkwright      03/10/13 17:13      
            I don't use it frequently, but when I need it, I NEED it      Richard Erlacher      03/11/13 05:24      

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