[Noisebridge-discuss] arduino usb host shield - seeking help or advice for project

[Jonathan Foote]

The USB stack is really complex, and the host side particularly so as
it must support a huge range of devices. Since you ultimately want to
talk to a serial device, using USB is pretty much overkill IMHO. It
may work, but if it doesn't it's going to be a bear to debug.  In
particular the MAX3421E may not recognize the PID/VID  for your
particular flavor of USB->serial.

If you can get to the Tx and Rx on your device, the easiest solution
*by far* is to interface that directly with the UART on the AVR. If
the voltages are compatible (5V? 3V3?) you should be able to directly
connect Tx, Rx, and ground and it will work.

As you know, the AVR UART is very capable and can easily handle most
baud rate and stop bit configurations.

If you really want to use USB, another option is to use the ATMega8U2
on board the Uno, and reprogram it with the LUFA stack as a virtual
serial host. In this case you can poke at the code and make sure it
enumerates your devices' PID/VID.

HTH.





On Mon, May 9, 2011 at 1:09 AM, Steve Castellotti <sc at puzzlebox.info> wrote:
> Hey all--
>
>
>     I want to be able to shoot fireballs with my mind.
>
>
>     (...now that I have your attention...)
>
>
>     I've run into difficulty working on an Arduino project and was hoping
> someone might be able to lend a hand or point me in the right direction.
>
>     Long story short, I have a USB dongle which appears as a serial device
> to Linux and I would like to control it from an Arduino (without a PC). To
> this end I have picked up one of these shields from SparkFun to make my UNO
> look snazzy:
>
> http://www.sparkfun.com/products/9947
>
>
>     I have working code and good experience with the hardware (and serial
> devices in general) on the Linux side, and if I could get to the point where
> I can write a single hex packet to the Rx port of this USB device and read
> back the result, I could take everything from there.
>
>     I even have schematics for the USB dongle from the manufacturer and a
> walkthrough from someone who's cut the traces and used a SparkFun Level
> Converter to talk to the hardware directly. I figure the USB Host shield is
> far less invasive and would provide good experience for future projects.
>
>     There's a reasonable degree of information about the USB Host shield (or
> at least a compatible model) online:
>
> http://www.circuitsathome.com/usb-host-shield-hardware-manual
>
> http://www.circuitsathome.com/mcu/ps3-and-wiimote-game-controllers-on-the-arduino-host-shield-part-1
>
> https://github.com/felis/USB_Host_Shield
>
> http://www.circuitsathome.com/mcu/arduino/usb-shield/troubleshooting-arduino-usb-host-shield
>
>
>
>     Is anyone around either tomorrow (for Circuit Hacking Monday) or Tuesday
> (before/after the meeting) who might have a few minutes to take a look? I've
> started to have a play, reviewing and experimenting with the example
> libraries, but its all a bit of a strain on my (limited) electronics
> knowledge.
>
>
>     Oh, and the end goal really is to shoot fireballs with the mind. But
> more on that another time... (c:
>
>
>
> Cheers
>
> Steve
>
>
>
>
>
>
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>