单片机模拟c64key USB键盘

Spaceman Spiff's Commodire 64 USB Keyboard (c64key for short) is is free software; you can redistribute it and/or modify it under the terms of the OBDEV license, as found in the licence.txt file. c64key 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 OBDEV license for further details. This is the README file for Spaceman Spiff's Commodore 64 USB Keyboard. Spaceman Spiff's Commodore 64 USB Keyboard (c64key for short) is a USB HID Keyboard device built into an old Commodore 64 "breadbox", allowing the (rather crappy but highly nostalgic) keyboard of a C64 to be used as an input device for e.g. a PC. Of course this allows the keyboard to be used in conjunction with a C64 emulator to get the right nostalgic feel, but this use has not been tested, and the conversion of scan-codes may result in less optimal results in this case. The basis of the project was Objective Development's HIDkeys demo application, although a great deal of modifications had to be made in order to scan a proper keyboard matrix, as well as report more than one keypress at a time. This also meant the HID report format had to be altered. Two different versions of the hardware can be used. One uses an Atmel ATmega8, whereas the other uses an Atmel ATmega16. For the ATmega 16 version it is the idea to allow the extra I/O-ports to be used for scanning two C64 joysticks connected to these, and reporting these as joystick events. Unfortunately I have not yet been able to get the composite USB device working correctly, so currently the code only supports the keyboard. There is therefore no functional difference between the ATmega8 and ATmega16 versions. The code in m16keyjoy is experimental, and does not currently work. Both configurations use a 12MHz crystal, and USB interfacing implemented with very simple hardware. Apart from that, the microcontroller handles decoding and debouncing of the 66 keys on the C64 keyboard, and using Objective Development's firmware-only USB driver sends decoded scan-codes to the PC over low-speed USB. For the ATmega16 version a composite device is created, allowing the unit to function as both a keyboard and a joystick/gamepad. Objective Development's USB driver is a firmware-only implementation of the low speed USB standard (USB 1.1) which can be used on cheap AVR microcontrollers from Atmel. A detailed description of the features and limitations of OBDEV's AVR-USB can be found in "usbdrv/usbdrv.h". More information is available on Objective Development's homepage: http://www.obdev.at/products/avrusb/ Building the hardware --------------------- The hardware for the c64key is quite simple. Circuit diagrams are included in the directory "circuit" in PDF and PNG formats. The USB interface hardware is based on Mindaugas Milasauskas' MJoy application (http://www.mindaugas.com/projects/MJoy/). Apart from that, the only interesting things are the 12MHz crystal and the connector interfacing to the C64 keyboard matrix. No circuit board layout is published, mainly because the application is so simple that it is easier to realize on a perf-board (strip-board), but the diagram should provide all needed information to create your own implementation, whether on a perf-board or with printed circuit boards. The connector CON1 is used for programming the microcontroller. The connections used are the same as the 6-pin ISP connector used by Atmel, and available on their programmers (such as the STK500 kit). Instead of the old behavior where PD1 could be used for UART debug, it is now used for the caps lock LED (if you want this). Of course this can also be disabled if the UART debugging is needed. Building the firmware --------------------- The c64key firmware requires avr-gcc and avr-libc (see http://www.nongnu.org/avr-libc/ for more details). Before attempting to compile, edit the Makefile to select the desired keyboard mapping and programmer options. For the easiest approach, you can use WinAVR under Windows, which is a bundle of the required libraries and tool-chain packaged for Windows. It even comes with a good editor (Programmers Notepad), which was used for the development throughout this project. WinAVR is available from http://winavr.sourceforge.net/. After installing WinAVR you should be able to run the command "make" from the directory where the source code is located, which will build the firmware. The "Makefile" included with the project is based on an example from the WinAVR distribution, and has support for burning the firmware to an AVR device through a range of different programmers supported by the AVRdude programming utility. With a few modifications to the Makefile it should be possible to accomplish this programming by issuing the command "make program". Of course these commands can also be executed from within Programmers Notepad. Of course you will need some programming hardware to connect between the circuit and the PC. Several possibilities exist (and are supported by AVRdude), including some very simple programmers that can be built on a tight budget. During the experimentation and development of this project, I have used an STK500 development board from Atmel. If you have the possibility of getting one of these, I can highly recommend it, not only as a programmer, but for a wealth of experiments that can be done on the board, before any hardware needs to be built. It is important that the fuses of the microcontroller are set correctly before the application will work. The most important thing is to configure the device to use an external crystal. The AVR device is configured to use the internal RC oscillator from the factory, but this is not sufficiently accurate to handle the delicate timing required for USB communication. Each of the Makefiles have a target called fuses, which uses avrdude to set the fuses for the device (provided the avrdude settings in the Makefile have been configured in an appropriate way). Be aware that the firmware provided here does not use OBDEV's USB vendor ID, since this may not be used for HID devices. Instead John Hyde's VID is used (same as OBDEV's HIDkeys example). John has aggreed that his VID can be used for educational purposes, so please MAKE SURE THIS FIRMWARE DOES NOT ESCAPE YOUR LAB (or get a different VID). Files ----- readme.txt This file. changes.txt What has been changed in the different versions. c64key.ppg Project Group file for Programmers Notepad. doc.txt Further documentation. license.txt The license this project is released under. circuit/ Directory with circuit diagrams in PDF and PNG formats. usbdrv/ Directory with the AVR-USB driver and docs. m8key/ The firmware for the ATmega8 version. m8key/m8key.pnproj Programmers Notepad project file for ATmega8 version. m8key/Makefile Build-file for the GNU Make utility. m8key/main.hex Binary version of the ATmega8 firmware. m8key/main.c The main firmware functions (ATmega8 version). m8key/usbconfig.h Configuration file for the AVR-USB driver (ATmega8). m16key/ The firmware for the ATmega16 version. m16key/m16key.pnproj Programmers Notepad project file for ATmega16 version. m16key/Makefile Build-file for the GNU Make utility. m16key/main.hex Binary version of the ATmega16 firmware. m16key/main.c The main firmware functions (ATmega16 version). m16key/usbconfig.h Configuration file for the AVR-USB driver (ATmega16)