IBM 4704 to USB keyboard converter

This firmware converts IBM 4704 keyboard protocol to USB HID.

Keyboard initialization process takes a few seconds at start up. During that you will hear buzzer from the keyboard. You need to plug USB cable after hooking up your keyboard to the converter.

Update

• 2015/09/07 Added keymap for Alps 102-key. Thanks, tai @ geekhack!
• 2015/05/05 Added keymaps for 107-key, 77-key and 50-key. Thanks, orihalcon @ geekhack!
• 2015/05/19 Fixed a protocol handling bug.

Supported Keyboard

IBM capacitive switch models:

• 6019273 Model 100 50-key (grid layout) http://kishy.ca/?p=894
• 6019284 Model 200 62-key Alpha(60% layout) http://kishy.ca/?p=894
• 6019303 Model 300 77-key Expanded Alpha http://deskthority.net/photos-f62/ibm-6019303-t8502.html
• 6020218 Model 400 107-key Full key http://kishy.ca/?p=894

Alps switch(vintage Green) models:

• 5954339 Japanese 102-key http://deskthority.net/post87127.html#p87127
• 6112883 Japanese 102-key http://geekhack.org/index.php?topic=52888.msg1194489#msg1194489
• 6112884 Japanese 102-key http://geekhack.org/index.php?topic=50437.msg1193047#msg1193047
• 6341739 Chinese 102-key http://geekhack.org/index.php?topic=52888.msg1176566#msg1176566

Connector

Keyboard Plug from front:

DSUB-9
-------------
\ N 2 3 4 5 /
 \ N N N N /
  ---------
2   GND
3   VCC 5V
4   DATA
5   CLOCK
N   No connection/No pin.

Connection

In case of using ATMega32U4/U2

1. Supply power with VCC and GND.
2. Connect CLOCK to PD1 and DATA to PD0. You can change pin with config.h.
3. Optionally you may need pull-up register. 1KOhm probably work.

TMK Converter can supports IBM 4704. https://github.com/tmk/keyboard_converter

Build Firmware

Just run make:

$ make -f <makefile>

For TMK Converter rev.1 use Makefile.tmk_rev1 as makefile:

$ make -f Makefile.tmk_rev1

For TMK Converter rev.2 use Makefile.tmk_rev2 as makefile:

$ make -f Makefile.tmk_rev2

To select keymap:

$ make -f <makefile> KEYMAP=[plain|...]

To indentify your TMK Converter revision see this.

Keymap

Several version of keymap are available in advance but you are recommended to define your favorite layout yourself. To define your own keymap create file named keymap_<name>.c and see keymap document(you can find in top README.md) and existent keymap files.

Use KEYMAP_ALPS102() to define your keymap for Alps models.