On 11/23/05, David P Harris <dpharris@telus.net> wrote:
> I have been following the discussion on scopes on the PICLIST.
> MultiAnalyser@yahoogroups.com is the off-shoot group discussing
> developing a Multianalyzer, ie an oscilloscope and logic analyzer.
>
> In the meantime, I had another look at my Spartan-3 development board
> that I bought.
> <http://www.xilinx.com/xlnx/xebiz/designResources/ip_product_details.jsp?key=HW-SPAR3-CPLD-DK>
>
> I have decided to develop a (rudimentary) logic analyzer with it.  It
> includes a Spartan-3 FPLA (200,000 gate) with a 50MHz clock, 2 x 256k x
> 16 SRAM, and RS232, PS/2 mouse/keyboard and VGA ports, 4 buttons, 8
> slide switches, and 4 digits of 7-segment.  They include a demo with a
> 640x480 VGA display with 8x8 characters of 16 colours with a PicoBlaze
> microprocessor core implementation.
>
> My plan is to suck 16 channels of digital data into the SRAM with the
> FPGA hardware and then display it to VGA with the microprocessor core,
> and use the pushbuttons/switches for a UI.
>
> Now my questions:
>
> 1. Should I sample at some suitable sample rate (<50MHz) directly into
> the (up to) 512k x 16 SRAM?  Display would be to scan through the array
> and plot the results into VGA RAM.
> 2. Should I sample at 50 MHz and save the time of the transitions into
> (up to) 256k x 32 SRAM?
> 3. Should I  implement  triggers (or cursors) in software, indicating
> where they are by pattern matching .  Conversely, 1-8 triggers could be
> implemented in hardware, using 1-4 bits to indicate the active cursor.
> 4. How are glitches usually handled?  It would appear #2 would pick
> these up.
> 5. Drawing the display might be slow -- could be implemented in
> hardware, too.
>
> Anyway, I figure its a good project to learn VHDL :-) -- the demo
> already blinky de lights.
>
> Any words of advice or ideas would be welcome :-)
>
> David
> PS- perhaps with the addition of a front end and a coupla ADCs, it could
> become an oscilloscope, too.
> It is possible to increase the clock rate with another crystal, as it
> has a socket for this.
>
>
>
>
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