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

2015/05/05 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(Teensy2.0):

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.

Build Firmware

Just run make:

$ make

To select keymap:

$ make KEYMAP=[plain|...]

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.