Dave (Curtis):

The AT90USBKEY is a neat and inexpensive board.

> On the subject of hosts -- one thing I am excited to play with but
> haven't had a chance, is the Atmel AT90USBKEY development board.
> This board is $36 at Digi-Key.

I just checked, it seems to be $31.92 at Digi-Key.

> It has an AT90USB processor, some on-board
> dataflash, misc switches and LED's, and the rest of the
> I/O broken out. > It has a USB-On-The-Go connector, so
> it can be either a USB host *or* device. Dean Camera has
> written a project with GPL'ed USB class drivers
> for a bunch of useful devices. See:
>
> http://www.fourwalledcubicle.com/MyUSB.php
>
> There is a broken-out serial port on the AT90USBKEY. I'm thinking a
> nice RoboBricks2 host interface could be built by attaching a CAN
> transceiver as a small daughter board. You could not only interface
> your robot as a USB device, but since it has an OTG connector you could
> plug in a keyboard, joystick, or other standard peripheral.
>
> And... since it comes factory pre-programmed with a bootloader, you
> don't need to buy a development system. All you need is the avr-gcc
> tool chain. (Of course, without at ICE you have to do all your
> debugging with 4 LED's). I'm not sure, but I think a Dragon can debug
> in the first 32K of program flash on the AT90USB, but you should double
> check.

My further comments are:

1) The AT90USBKey has a AT90UBS-1287 part on it. Since it
has 128KB of flash, it is not listed as compatible with
the AVR-Dragon, which is restricted to 32KB of flash.
It *may* be possible to work on the firsth 32KB of memory,
but I do not know one way or the other.

2) The AT90USBKey is debuggable using the AVR-JTAG-ICE.

3) PORTA through PORTF use .050" x .100" connectors. These
connectors have two serious problems:

A) It is very hard to find female sockets at that size.

B) The pins are so tight that the PCB design rules usually
require a manufacturer that can guarantee 5 mil trace
separation. Most Hobby level PCB manufacturers are at
8 or 10 mil trace separation.

I was able to use these connectors once in my life, and
pain was so great that I convinced the gentleman who
designed the original board to switch connectors for
the next board revision.

4) It is probably possible to side step the connector problem
by simply soldering in a solid wire.

5) I really, really want a RoboBrick with USB connectivity,
working with this board looks like a major project. I'm
willing to consider the project only if somebody else is
going to actually help out. This may involve buying an
AVR JTAG ICE Mk II, designing a daughter board etc.

Comments?

-Wayne