This firmware converts the protocol of Apple Macintosh keyboard M0110, M0110A and M0120 into USB. Target of this project is USB AVR controller ATmega32U4. Using this converter you can revive these retro keyboards with modern computer.

Pictures of M0110 + M0120 and M0110A.

M0110A support was contributed by skagon@github.
M0120 also is supported. keys(+ * / and ,) on M0120 are recognized as cursor keys.

Update

2013/08: Change port for signals PF to PD
2013/09: Change port again, it uses inversely PD0 for data and PD1 for clock line now.

Building Hardware

You need 4P4C cable and ATMega32U4 board like PJRC Teensy. Port of the MCU PD1 is assigned to CLOCK line and PD0 to DATA by default, you can change pin configuration with editing config.h.

4P4C phone handset cable

Note that original cable used with Mac is straight while phone handset cable is crossover.

http://en.wikipedia.org/wiki/Modular_connector#4P4C

Close-up picture of handset cable. You can see one end of plug has reverse color codes against the other. Click to enlarge.

Socket Pinout

http://pinouts.ru/Inputs/MacKeyboard_pinout.shtml

Pull-up Resistor

You may need pull-up resistors on signal lines(CLOCK, DATA) in particular when you have long or coiled cable. 1k-10k Ohm will be OK for this purpose. In that case the converter may not read signal from keyboard correctly without pull-up resistors.

Building Firmware

To compile firmware you need AVR GCC. You can edit Makefile and config.h to change compile options and pin configuration.

$ git clone git://github.com/tmk/tmk_keyboard.git (or download source)
$ cd m0110_usb
$ make -f Makefile clean
$ make -f Makefile

and program your Teensy with PJRC Teensy loader.

Keymap

You can change keymaps by editing keymap.c.

M0110 & M0120

Default Layer

,---------------------------------------------------------.     ,---------------.
|  `|  1|  2|  3|  4|  5|  6|  7|  8|  9|  0|  -|  =|Backs|     |Clr|  -|Lft|Rgt|
|---------------------------------------------------------|     |---------------|
|Tab  |  Q|  W|  E|  R|  T|  Y|  U|  I|  O|  P|  [|  ]|  \|     |  7|  8|  9| Up|
|---------------------------------------------------------|     |---------------|
|Caps  |  A|  S|  D|  F|  G|  H|  J|  K|  L|  ;|  '|Enter |     |  4|  5|  6| Dn|
|---------------------------------------------------------|     |---------------|
|Shift   |  Z|  X|  C|  V|  B|  N|  M|  ,|  ,|  /|Shift   |     |  1|  2|  3|   |
`---------------------------------------------------------'     |-----------|Ent|
     |Ctl|Gui |         Space               |Alt |Ctl|          |      0|  .|   |
     `-----------------------------------------------'          `---------------'

Space and Enter also work as Fn layer switch key when holding down.

Function Layer(WASD/HHKB)

,---------------------------------------------------------.     ,---------------.
|Esc| F1| F2| F3| F4| F5| F6| F7| F8| F9|F10|F11|F12|Delet|     |Nlk|  -|Lft|Rgt|
|---------------------------------------------------------|     |---------------|
|Caps |Hom| Up|PgU|   |   |   |   |Psc|Slk|Pau|Up |Ins|  \|     |  7|  8|  9| Up|
|---------------------------------------------------------|     |---------------|
|Caps  |Lef|Dow|Rig|   |   |   |   |Hom|PgU|Lef|Rig|Enter |     |  4|  5|  6| Dn|
|---------------------------------------------------------|     |---------------|
|Shift   |End|   |PgD|   |   |   |   |End|PgD|Dow|Shift   |     |  1|  2|  3|   |
`---------------------------------------------------------'     |-----------|Ent|
     |Ctl|Gui |         Space               |Alt |Ctl|          |      0|  .|   |
     `-----------------------------------------------'          `---------------'

M0110A

Default Layer

,---------------------------------------------------------. ,---------------.
|  `|  1|  2|  3|  4|  5|  6|  7|  8|  9|  0|  -|  =|Backs| |Clr|  =|  /|  *|
|---------------------------------------------------------| |---------------|
|Tab  |  Q|  W|  E|  R|  T|  Y|  U|  I|  O|  P|  [|  ]|   | |  7|  8|  9|  -|
|-----------------------------------------------------'   | |---------------|
|Caps  |  A|  S|  D|  F|  G|  H|  J|  K|  L|  ;|  '|Enter | |  4|  5|  6|  +|
|---------------------------------------------------------| |---------------|
|Shift   |  Z|  X|  C|  V|  B|  N|  M|  ,|  ,|  /|Shft| Up| |  1|  2|  3|   |
|---------------------------------------------------------| |-----------|Ent|
|Ctrl |Gui    |         Space             |  \|Lft|Rgt|Dwn| |      0|  .|   |
`---------------------------------------------------------' `---------------'

Space and Enter also work as Fn layer switch key when holding down.
Backslash(\) also works as Alt when holding down.

Function Layer(WASD/HHKB)

,---------------------------------------------------------. ,---------------.
|Esc| F1| F2| F3| F4| F5| F6| F7| F8| F9|F10|F11|F12|Delet| |Nlk|  =|  /|  *|
|---------------------------------------------------------| |---------------|
|Caps |Hom| Up|PgU|   |   |   |   |Psc|Slk|Pau|Up |Ins|   | |  7|  8|  9|  -|
|-----------------------------------------------------'   | |---------------|
|Caps  |Lef|Dow|Rig|   |   |   |   |Hom|PgU|Lef|Rig|Enter | |  4|  5|  6|  +|
|---------------------------------------------------------| |---------------|
|Shift   |End|   |PgD|   |   |   |   |End|PgD|Dow|Shif|PgU| |  1|  2|  3|   |
|---------------------------------------------------------| |-----------|Ent|
|Ctrl |Gui    |         Space             |  \|Hom|End|PgD| |      0|  .|   |
`---------------------------------------------------------' `---------------'

Debug

You can use PJRC HID listen to see debug output. The converter has some functions for debug, press <Command>+H simultaneously to get help.

Command: Shift+Option+Command(Shift+Alt+Gui or Shift+Alt+Control)