RE: wonderboard

Marc;
If I understand correctly, your vision of wonderboard included the ability
to use it for a variety of applications outside of the original scope. This
was to provide a bonehead simple means of interfacing the parallel port to
step drivers, limit switches and four general outputs. To elaborate,
stepper systems are the logical choice for a beginning
experimenter/hobbyist. They are simple, cheap, and plenty of ready to run
software is available (in addition to CNCPro). Wonderboard helps to
eliminate some of the problems beginners face, the biggest of which seems to
be connecting the dots.

Don't misunderstand me. Perhaps it's possible to incorporate the I/O
capabilities you describe without comprimising the original vision. I lack
sufficient knowledge of digital electronics to be the judge of this. Can we
do it?

Doug

> -----Original Message-----
> From: D.F.S. [SMTP:dfs@...]
> Sent: Thursday, February 24, 2000 12:18 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] wonderboard
>

<snip>

> Here is MY take on the interface.
> To give the most flexibility and largest address space to the interface
> We could make access a 1,2 or 3 step process as necessary.
>
> First Write an address and command string, the only command I can
> think of at the moment is read or write.
> Something like:
> 0 1 1 0 1 0 0 1
> ? ^ +-adderess+
> |
> 0 for read 1 for write
> The lower 6 bits are the address for 64 possible locations.
> This would allow 512 bits of input/output.
>
> Watch for a ready signal on one input line(If Appropriate)
> Read or Write the data.
>
> I would suggest presuming a bi-directional interface and not do the
> 4 bit crap.
> The PS/2 type bi-directional interface has ONLY been around for 13 years.
> It SHOULD be supported even in junker type $5.00 hardware.
>
> Use the additional I/O bits on the port for stuff like the ready flag
> mentioned above.
> The only time I can think of right off the ready bit would be used
> would be handshaking for talking to an external CPU or something,
> A delay for an A/D converter to do a conversion after a read request,
> and to sync up to another external action.
>
> Otherwise this thing would run in a latched state and you could set
> up some of the TTL buffers, to pass data straight thru and would
> have any input changes instantly show up at the printer port until
> you set a new address.
>
> Such a system could easily be built with TTL parts, and with a simple
> design based on latches it would be easy to understand and troubleshoot.
> A lot simpler than the 8255 btw.
>
> Adding an Eprom directly wired to a pair of 7 segment displays could
> decode the address at any given instant and show the number of the
> currently active port in decimal digits.
> Then again maybe it would change too fast to bother with...
>
> BG Micro has 7500 V optoisolators for 17 Cents.
>
> Marc
>
>
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