I plan on ordering an AT90USBKEY today. Thanks to all who share here.

Looking in the message list under #339 and following there was
http://tech.groups.yahoo.com/group/chordite/message/353

Which asks, "What hardware in total is needed?"

It would seem some 7 switches, and a ribbon cable (and maybe a
pin & socket header pair in the middle of the ribbon cable),
that is enough.

For software it is all free with the AT90USBKEY package,
or downloadable from Atmel, and load John's Hex file...

You buy the board, wire the switches to it and then use the
free Atmel Flex programmer to program it. It's a slam dunk.

which will be clear once I have the AT90' plugged into the port.

So, if the above is all true, how does one wire any and all
accessories?

In the Hardware User's Guide schematic, Jack 6 has as inputs:
Pin 1 = Vcc
Pin 2 - Gnd
Pin 3-10 are inputs (7->0).

Also shown is the Joystick interface which uses Port B 5,6,7
and Port E 4,5.

Minor point: so we can't use the joystick here as that
leaves only 5 inputs available.

Having figured that out, How are the switches wired?
(There are 7, among 4 fingers, and distal and proximal placement. )
I am assuming we have a common connection (either +Vcc or ground)
among them and pull them High or Low via switch closure.

Given the Joystick configuration, I bet they get pulled to ground
via the switches, and have pullup resistors (or current sources)
that are already part of the AT90.

Then which switch goes to which pin on Jack 6? (Or to which
port of port B?)


I can't seem to find the Marquardt 6450(?) switches in less
than quantities of 24. Anybody have an idea?

The other switches are findable in small quantity I suspect.

The tiny 0.050 pin spacing seems tough to find a header for,
at lesat in small quantities. A shame. I saw the AVR
discussion about them. Seems to have petered out.

Thanks,
-Sandy