This is a Rotary-Dial-to-USB-Interface, based on the USB AVR Lab (http://www.ullihome.de/wiki/USBAVRLab/index). For the schematics of the USB AVR Lab, see http://www.ullihome.de/wiki/USBAVRLab/Download This is a tiny board with an ATMEGA8 speaking USB using the V-USB library. It features a 10-pin-port with some AVR pins routed out, and also has a bootloader, so it can be programmed without an ISP adapter, using USB. The Rotary-Dial-to-USB-Interface expects a rotary dial to be attached against PB4/5. When you look at the front of the connector: ____ ____ | 9 7 . . . | Attach the two cables for the idle switch at 9 and 0. | 0 8 . . . | Attach the two cables for the dial pulse switch at 7 and 8. ----------- (0 and 8 are routed to GND, 9 and 7 to PB4 and PB5.) The program expects the "idle"-switch to be open when the dial is idle, and to be closed when the rotary dial is not in its idle position. The "pulse" switch is expected to be closed most of the time, and to be only opened shortly for each pulse. (This can be adapted easily). When attached to a computer, the device acts like a USB HID keyboard, no additional drivers are needed. If you want to enter the bootloader, then generate more than 17 dial pulses by dialing a zero, not letting the dial return fully into idle position yet, and pulling it to zero again. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . For details, see main.c