USB Caps Locker

[highwayman]

So.... I have wanted to make this project for a while:
http://macetech.com/blog/?q=node/46
And April 1 is approaching. I made some boards with the ATTiny 85, resistors, capacitor, no zener, no crystal. I flashed the hex into the chip. Plug it into a USB port.

USB Device not recognized
Device Status: Windows has stopped this device because it has reported problems. (Code 43)

It shows as an Unknown Device. Do I need specific drivers (that can be installed quickly)? Are there certain fuse settings? I think that I read somewhere about setting the fuses for the PLL of the ATTiny85?

Any further assistance would be greatly appreciated.

[blargg]

Correct me if I'm wrong, but doesn't this put 5V signals over the USB data lines? I don't see anything to drop the +5V from USB that powers the '85 I wouldn't connect this to anything I cared about. I'm amazed that the author of this project would remove the zener diodes just to save a few components (as stated on the page), while making it violate the USB spec and possibly damage the USB port.

[Guest]

Good call blargg!

Restarted a new project (codeandlife.com with ATTiny2313). Able to install the hardware driver and communicate with the 2313 when it was powered at 3.3V. Same set-up gives "USB Device not recognized" when powered at 5V.

Again...Thanks!

[horo]

Hi,

Another solution would be to cut the connection to USB pin 1 (Vcc) and insert either a red SMD LED or two normal SMD diodes in series to drop the voltage from 5V down to about 3.5V - that's close enough to the 3.3V from the specs. I never had problems with the two-diodes-solution.

Ciao, Martin