Hi, Tom

>     One little `pet' project is an 8-Bit Logic Analyzer core using the
above
> device. It would allow expansion in banks of 8 channels, each with their
own
> clock source or combined with other banks. The core includes an 8-Bit
> Trigger comparator with Bit-enables, 15-Bit free running SRAM address
> counter, control logic (ARM, TRIG, etc), and a 15-Bit post Trigger
counter.
> It is designed to support fast 32KByte SRAM.

    Yes, Yes, Yes and Yes... That is exactly the kind of thing I would just
love to put my hands on :-) I have to do much debugging in the field and
have had many times where I was inside a train or a bus modifying progams
and would love to have any scope or logic analyser in my hands !! Most
professional instruments are too big and need to be plugged to the AC line.
I have a bitscope that I adapted to be used with batteries but it is still
very ackward to get everything plugged and running. My dream is a small 10
bits scope and 8 or 16 channels logic analyser that I can plug to the
palmtop and see my signals changing all around. It would make life so much
easier !

> There are just too many
> trade-offs to be made and there is a good reason commercial units costs a
> fortune...

    It all depends on the application. I would not learn to live without my
100 megs digital scope but I do not need it most of the time. A small
instrument that I can taylor to my needs would be very welcome. I could
change the program to capture in a different way or show the results upside
down if I needed it ! I cannot do it with my gagescope and it is impossible
to use inside a running bus ! Specially if I make a mistake and cut the
engine suddenly :-) I have done that and my laptop and bitscope flew to the
floor :-(

> However, simple data capture with fairly versatile trigger and
> clock options can go a long ways.

    If we could trigger using 2 words in a sequence it would make the
instrument even more valuable. That would help a lot to debug programs and
get a nice trigger signal for the scope. Not essencial but nice. I would not
mind having the memory as a circular buffer and have the trigger point
always in the middle of the captured memory or have it at a fixed position.
The post trigger size could be fixed to make the design easier. If we have
enough memory the clock options can be simpler also.

>     You mentioned using a "palmtop". One of the advantages of these
devices
> are their low current consumption.

    Small batteries would make it even more usable. I could have the board
with PLD's, analog front end and microcontroller in a small box with some
NiCd's and the palmtop over the serial cable. Wow, that is a dream :-) It
could sit on my desk and I could get the oldie scope and let it sit under
the desk and I could keep both my hands to hold myself when I get inside
moving things !

Best regards,
Alexandre Guimaraes

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