Re: USB chip

[cas <cas_news@strotmann.de>]

David Murray wrote:

> 
>> On the Atari 8bit (also 6502, 64 KB RAM) we use the Cypress SL811HS USB
>> Controller. There might be better USB Controller available now, but the
>> plus for the Cypress is that for this chip some 6502 Drivers already
>> exist.
> 
> I wonder if it might be possible to integrate to the user-port.  I know
> I have seen some USB chips that converted USB to essentially a serial
> I/O for use in microcontrollers and such.  However, they seem to be
> always designed as a slave device.  I don't think I've come across such
> a device that works as a master.
> 
> The reason I'm interested (of course) is that I've considered trying to
> impliment USB on the DTV.

The reason for us to choose the Cypress SL811HS was

* available in small numbers for a reasonable price (appr. 8 Euro/US$)
* can be (full) master and also slave
* easy to program / Documentation available / Linux Driver available

on the Atari, the SL811HS is mapped with 2 Byte into the Atari Main Memory.
The SL811HS has 256 byte of Controller Memory (16 memory mapped register,
rest is USB packet buffer). The two mapped locations in the Atari Memory
are a memory select and memory read/write. That is from the Atari we select
the Byte inside the SL811HS in the Memory Select and the use the Memory
read/write to read from or write to the USB Controller. The Memory Register
is auto-increment, so when writing or reading a USB Packet, one needs to
set the select register only once and then read or write all packet bytes
from the memory access register.

USB2Serial Devices are a different kind of application, they are USB slave
devices that bridge or tunnel RS232 communication over USB. There is no way
to do USB Storage or HID (Human Interface Device) Communication over a
USB2Serial Device. It's only plain RS232. So no USB Keyboard, Mice or USB
Flashstick can be driven over an USB2Serial Chip (like the Profilic Chips).
We needed 1 year in 2003 to learn all this, and then to throw away the
first version of our hardware because we had choosen the wrong chip back
then.

Carsten