From: Marko Mäkelä (msmakela_at_gmail.com)
Date: 2008-03-05 14:41:07
On Wed, Mar 05, 2008 at 02:08:05PM +0100, Antitrack@networld.at wrote:
>
> Quoting Spiro Trikaliotis <ml-cbmhackers@trikaliotis.net>:
>
> > Hello Alex,
> >
> > You need to be able to gather (and send) data at 1.5 Mbit/s for USB 1.1
> > low speed.
>
> Ouch, such a high speed is really required? What is my USB mouse doing, then?
> Is it also sending the x/y coordinates data at _that_ speed?
Yes, when the host polls it for data. USB is a packet-oriented
master-slave serial bus with a tree topology.
> And there is no "inofficial" trick to circumvent the speed problem in sight?
Not that I know. Besides, Christian Starkjohann from obdev.at (the guy
behind the AVR-USB bitbanging driver for Atmel AVR microcontrollers,
http://www.obdev.at/products/avrusb/index.html) wrote me some time ago:
>> Es gibt zwar eine Low Speed USB Host Implementation in Firmware fuer
>> den AVR, aber es gibt keine USB memory sticks in low speed und das GPS
>> ist sicher auch Full Speed.
I was interested in implementing a data logger that would talk to a GPS
receiver and a USB Storage device. According to him, these devices
most likely except the host to do 12 Mb/s or 480 Mb/s, which requires
dedicated hardware. (For the record, I decided to wait for a decent
programmable GPS-enabled mobile phone.)
There are some USB host interface chips that could be useful. Some time
ago, I read that there is a USB HID (keyboard and mouse) driver for the
Atari 8-bit computers. Probably it was using some parallel-to-USB or
SPI-to-USB chip, such as the MAX3421E. (Please don't confuse these with
the likes of the FTDI FT232 or FT245; they are for USB devices.)
Marko
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