Re: Freed Z80 USB port - Success!

[Alex Freed <alex_news@mirrow.com>]

Steven Hirsch wrote:
> All,
>
> Can't keep this to myself :-)  About 10 minutes ago, I was able to 
> successfully transfer files back and forth between minicom on my Linux 
> box and the ZMP comm program on the Freed Z180 card.

That is a z80 card. Works well enough so there may not be a pressing 
need for a z180 card now :)

> Getting USB working was quite a battle, complicated by the fact that the 
> base circuit board did not connect everything that was needed.  I assume 
> because this functionality was in a prototype phase.

Yes. FTDI module is only one possibility for the board expansion.


> I have a configured ZMP that I will be glad to make available to anyone 
> that's following in my footsteps.  The I/O routines are quite stupid at 
> the moment and are doing everything in "byte at a time" mode, perhaps 
> the most inefficient way to use the packet-based USB bus.  

It's not all that bad if you consider that the FTDI chip has a 128 byte 
receive FIFO and a 384 byte transmit FIFO and the USB transactions 
usually happen on 64 byte blocks. No real need for another buffer IMHO.


> Next round I 
> will implement a receive buffer to drain incoming data a block at a 
> time.  Should speed things up considerably (even though it's not too bad 
> now).

Will be an interesting experiment.

-Alex.