[Coco] [Color Computer] USB Anyone?

[James Diffendaffer]

The MicroUSB project is using the same chip.  I think this is a newer
version of the one I looked at using for an Amiga interface... it's
very simple from a software driver standpoint.  

The main drivers would be:
Generic Keyboard
Generic Mouse
Generic Drive
Generic Joystick/Joypad

Too many others are proprietary and printers have changed a lot so
printer drivers would be a little more difficult than they used to be.


Layout is pretty easy.  The interface is very similar to the bubble
memory interface that appeared in Color Computer Magazine... it also
required 2 memory addresses and similar connectivity.

The non CoCo related stuff is right out of the sample design.
D0-D7 go to D0-D7 on the USB chip.
The CoCo R/W line is broken out into separate R and W lines which go
to the USB chip.  The R/W to separate R and W lines fits in one chip.
+5V goes through the VDD power circuit design provided by the
manufacturer.
A0 goes to the chip A0.
RESET goes to RESET. 
NMI to INT.
+5v and GND to the rest of the board.

If I use addresses FF5C-FF5F I can use the bubble memory design
exactly.  Using SCS simplifies address decoding so only A2, A3 and A4
of the address buss need checked.  It *can* be done with one chip and
it's output goes to CE on the USB chip.

I only need 2 or 3 chips to add a 16 bit IDE interface to this and it
sure wouldn't cost over $100.  At most another $10 in parts.

1 PAL/GAL + 2 74HCT373 chips would handle all the logic for USB, IDE
and interfacing a ROM.

My biggest roadblock is having to create a prototype board for the
CoCo connector since that size is rare these days.  I have a board
printing kit but cutting boards/edge connectors is a PITA.


--- In ColorComputer at yahoogroups.com, "John R. Hogerhuis"
<jhoger at p...> wrote:
> On Sat, 2005-04-16 at 03:28 +0000, James Diffendaffer wrote:
> > 
> > Anyone interested in a USB interface?
> 
> 
> FYI James Daggett made a run at this, and I think got as far as layout
> so you might be able to collaborate with him from the hardware angle.
> 
> The starting point was http://microusb.org
> 
> If someone ever comes up with hardware, I'm willing to help with some
> firmware. Plenty of driver work to go around since there are so many
> possible devices.
> 
> -- John.





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