[Coco] [Color Computer] USB Anyone?

[Phill Harvey-Smith]

James Diffendaffer wrote:
> 
> --- In ColorComputer at yahoogroups.com, Phill Harvey-Smith <dragon at a...>
> wrote:
[Snip!]

>>Had you considderd using something like one of the Xilinx CPLDs, 
>>something like an XC9572XL, this chip runs on 3.3v so will interface 
>>directly to the usb chip, but has 5V tollerent IO, so will also 
>>interface directly to the CoCo/Dragon bus without level shifters.
> 
> No need, the USB chip is 5V tolerant (See section 4.3.2 of the
> SL811HS.pdf file).  

Ok, that's an advantage.

>			The only reason I'd go with a PLD of any kind
> would be to reduce the board size.  I was thinking adding the IDE
> might require 2 extra chips for address decoding, bringing the total
> chip count 6 + USB + IDE connector.  That wouldn't fit in a small
> cartrige easily.  Now I think I can reduce that and get it to fit if
> the USB part isn't too big.

But also as I said in another post using programable logic has the major
advantage that if you make mistakes in the logic, you can reprogram the
device without having to rip tracks and rewire.

>> > My biggest roadblock is having to create a prototype board for the
> 
>>Depending on what PCB software you are using I have a library that I 
>>made that contains the Dragon/CoCo edge connector. 
> 
> Well, I have been trying to decide between FreePCB, Eagle, and PCB
> 123.  (No matter what program I use I seem to run into bugs)
> I'm sure I could find a way to convert it no matter what format it's in.

I'm using the hobby version of Eagle which IIRC cost $120ish, and allows 
me to do up to 4 layers up to eurocard size. I believe the free version 
will do half eurocard and 2 layers. My library is in Eagle format of course.

Phill.



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