[Coco] RPi DriveWire Success!

[Aaron Wolfe]

On Tue, Jan 14, 2014 at 3:13 PM, Joel Ewy <jcewy at swbell.net> wrote:
>
> Last spring I designed a CoCo cartridge housing in OpenSCAD and made one
> unsuccessful attempt to print it on my Thing-O-Matic.  It's almost too big
> to fit on the build platform, but I think I can make it work if I put a
> little more effort into it.  I did successfully print a case for the
> Raspberry Pi that I downloaded off of Thingiverse, so I know I can print
> something big enough to house the Pi.  The only problem with the PiPak would
> be that you'd have to have external cabling, unless you somehow run DW over
> the cartridge port.  Is that what you had in mind?

Well... it's in my mind, but I lack the hardware skill to do it :)

It would be neat to just house the Pi in a standalone rompak and
connect the various cables between that and the CoCo, so still using
bitbanger etc.

But.. The ultimate would be a pak that contained a Pi (or anything
similar, there are quite a few similar options out now) and interfaced
to the coco over the bus connector.

I know the Pi has GPIO pins and SPI etc, and the CoCo has... whatever
the bus connector provides.  From various conversations I know that
while it is theoretically possible to make the two talk, you need some
bits in between.

This could possibly be done with a chip that basically contains a
bunch of latches and speaks SPI, that was an idea that I think came
from John Kent (sorry if I've misplaced the credit/blame).  This was
interesting because the SPI interface meant the "adapter" would not be
tied to only the Pi, anything that speaks SPI could talk to it and
through it the CoCo bus.  There was a specific chip (I have in my
notes somewhere) that was fast enough and had enough latches to
probably work well on the coco bus.

I think some form of coco bus <-> modern protocol interface would
enable lots of fun projects, far beyond just the Pi in a Pak.  Maybe
SPI is good, maybe something else... unfortunately I am just not the
guy who is going to  figure that out.  I'll be the one writing
software to simulate all kinds of classic and new "peripherals" once
such an interface exists, though :)

-Aaron