[sdiy] Slightly OT, Logic Analyzers...

[trevor at resonance.fsnet.co.uk]

Hi,

Maybe use a combination of comparators of some sort? Use a common low threshold, high threshold reference to all of them. 

Just a silly thought. 

Trev



> 
> From: The Proteus <proteus at ugwarehouse.org>
> Date: Mon 05/Aug/2002 10:44 CEST
> To: Synthesizer DIY List <synth-diy at dropmix.xs4all.nl>
> Subject: [sdiy] Slightly OT, Logic Analyzers...
> 
> All,
> 
> 	I've been contemplating designing a very small logic analyzer with
> some Linux software to run it. One of the features I'd like to have is
> support for multiple logic types (TTL, CMOS, LVTTL, etc...). Now, from
> what I'd assume, the logic capture hardware is basically a latch being
> driven at high frequencies, and then that latch data is being stored in a
> buffer memory somewhere. That's all simple to me... the question I'm
> kicking around currently is how to get the input voltages in line with the
> latch. If you've got a 5V latch and the input is a LVTTL signal, how do
> you translate the high, low, and threshold voltages appropriately? This
> isn't a big deal for basic TTL<->LVTTL or CMOS<->TTL type circuitry, but
> when you get down to 1.8V and 1.5V Vcc rails, the appropriate level
> translator could get quite tricky to design - especially in commercial
> logic analyzers where there are 128+ channels. 
> 	Does anyone have any ideas on a good, low-cost level shifter I
> just described? Yes, my goals are lofty to top out at commercial analyzer
> channel counts, but hey... let a young kid have his dream. ;-)
> 
> Regards,
> 
> Prot
> 
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> 
> 


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