[Coco] [Color Computer] FYI: USB Modules & Add-Ons
John R. Hogerhuis
jhoger at pobox.com
Mon Sep 4 13:26:40 EDT 2006
On Sun, 2006-09-03 at 15:06 -0400, jdaggett at gate.net wrote:
> On 2 Sep 2006 at 23:30, Gene Heskett wrote:
> > And this is the major advantage over the FTDI devices shown on the same
> > web page as it appears these might be usable with nothing more than chip
> > select logic, and possibly a byte wide fifo for rx buffering. The cheaper
> > FTDI devices would also need an rs232 type uart, raising the
> > implementation cost considerably.
> The FT245B/R devices interface to a parallel 8 bit data buss. Same function as
> the FT232. The FT245B is $6.33 in unit cost and the FT245R is $4.94 unit cost.
> Like the Cypress SH811 device, someone has to write drivers for DEB/OS9 to
> make them useable. From best I can tell the FT245 would be a better solution
> than the Cypress chip due to errata and the lack of Cypress to correct some
> issues in the chip design.
I guess I missed the application being considered here?
The Cypress SL811HS is an embedded USB host controller which can be
interfaced to an 8-bit bus. That means you could hook arbitrary usb
devices to the coco (usb keys, usb storage (basically, SCSI-over-USB),
usb serial ports, etc. The FT245 is a usb device, you might use it to
interface a RS232 chip to a PC's usb host controller. Since a Coco has
no USB host controller, it has no obvious application for the Coco
unless you want to turn the coco into some kind of USB device.
What kind of slave device could one turn the coco into? Well, presumably
one could make the keyboard, joystick ports, cassette interface, etc.
available to a host PC. Might be interesting as a super emulator
interface. Would require a lot of hardware work. You wouldn't want the
6809 taking control of the bus ever, I guess.
When I think of adding USB to coco, I think of adding a USB host
The driver issue for Cypress part isn't a huge hurdle considering that
drivers already exist in C (from Cypress), 6502 assembly and in high
level Forth as well. Now if there is a serious functional issue with the
Cypress part that would be of concern but they seem to be doing ok with
the Cypress chip at http://microusb.org.
Are there any equivalent parts to the Cypress chip that implement a USB
Host Controller that can be interfaced to an 8-bit bus? Or perhaps just
use a PC USB host controller and add a CPLD to do the interface logic
that glues everything together.
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