aqui hay uno muy bueno! si alguien lo puede traducir y que se entienda!
Version 64 pin
I made a quick & dirty usb dongle board for running psgroove, so if anyone find it useful then here you go..
Made with freeware Eagle 5.9
The board should be pretty easy to manufacture since only one layer is required(with one jumper, the second layer in the brd file is only GND and can be left out).
The BOM count is minimal, with no "hard to find" parts.
I think all 64pin AVR's with USB should work, but I have only tried the AT90USB1287
Tested with psgroove and the default "USER" layout
BOM:
IC1 AT90USB1287 or similar
C1,C2 15p(10p-30p should be ok)
C3 1u(from atmel datasheet)
C4 1u(not a critical value, can live without it)
C5 0.1u(not a critical value)
LED1,LED2 SMD 1206
Q1 16Mhz OR 8Mhz
R1,R2 500 (about)
R3,R4 27 (about)
R5 2k (anything in 100-100k range)
EDIT:
The chips comes with an preprogrammed USB bootloader, use FLIP from atmel.com for programming
To enter bootloader mode, short the 2pin header, insert the dongle to the PC, force a reset(by shorting the reset TP to ground with a small screwdriver).
After programming remove the short on the header
To test the dongle after programming, insert into a pc and led2 should turn on. If it doesn't then hard force a reset(..by shorting the reset TP to ground..) I had to do this on 1 out of 3 tested pc's. You should now get a USB connection with ID aaaa:5555




Version 32pin
I made a version for 32pin devices - AT90CAN162, ATMEGA32U2 etc
note, ATMEGA32U4 is a 48 pin device, will not work..
BOM is about the same as the other version.
This design did come out much nicer but I will not be able to test it until late next week, but it _should_ work (I hope )
So if anyone want to beat me to it then here you go..
Flashing is a bit different:
-plug into pc
-short HWB tp to gnd (and hold it)
-momentarily short RST tp to gnd
-release HWB
Now you should get into the atmel bootloader
The board should work with the standard teensy board layout, but if you want to use both leds you have to modify the board file.


Este esta muy currado y ademas es pequeñisimo. A ver si alguien se anima y lo intenta.
Fuente: http://psx-scene.com/forums/showthread.php?t=65258