hhkb/doc/HHKB.txt

   1 Alternative Controller for HHKB pro
   2 ===================================
   3 I want to add vi cursor and mouse keys to HHKB. Original HHKB controller is not programmable and
   4 firmware source code is not open. So, customizing HHKB needs to replace original controller with programmable one.
   5 I used Teensy++ as alternative controller. Though a Teensy has enough ports to drive HHKB,
   6 Teensy++ has clean pinout and it makes programing and wiring easier.
   7
   8 This is just a proof of concept for replacing controller of HHKB, not a complete firmware.
   9
  10 My prototype firmware source tree is here:
  11     github(http://github.com/tmk/tmk_keyboard)
  12 This firmware is a port of my previous project:
  13     HHKB style Mod(http://geekhack.org/showwiki.php?title=Island:11930)
  14 PJRC:
  15     Teensy++/Teensy(http://www.pjrc.com/teensy/)
  16
  17
  18 Pros:
  19     * without pattern cutting, case mod  and soldering
  20     * can keep original controller intact
  21     * can change HHKB behaviour as you like(by C programming)
  22
  23 Cons:
  24     * void your warranty
  25     * unavailability of Teensy++/Teensy(because of PS3 cracking boom?)
  26
  27 Features:
  28     * customized keymap
  29     * more keymap layers
  30     * mouse keys for minimum mouse operation(never comfortable for normal use)
  31     * and more...(in the future)
  32
  33 Any suggestions or ideas are welcome.
  34
  35
  36 NOTE:
  37     My HHKB is just "Professional". This means followings may not be applied to "Professional2".
  38
  39 DISCLAIMER:
  40     I'm not a professional for electronics and MCU programming. This may damage your HHKB.
  41     And my English writing is poor, I'm not sure I can convey my notions accurately.
  42
  43
  44 Teensy++ installation
  45 ---------------------
  46 Angled USB mini B adapter is used to install Teensy++ laterally.
  47 (teensy_install.jpg)
  48
  49 Bread baord wires are used to connect Teensy++.
  50 (teensy_wiring.jpg)
  51 (connector_contact.jpg)
  52
  53
  54 HHKB internal
  55 -------------
  56 HHKB pro has some chips on separate two PCBs.
  57
  58 Controller PCB:
  59     M38K07M4    Renesas MCU with USB function
  60                 http://documentation.renesas.com/eng/products/mpumcu/rej03b0192_38k0ds.pdf
  61
  62     (HHKB_controller.jpg)
  63
  64 Keyswitch PCB:
  65     HC4051      Analog Multiplexer: select a row line.
  66                 http://www.alldatasheet.com/datasheet-pdf/pdf/203989/KODENSHI/KK74HC4051A.html
  67     LS145       BCD Decoder: select a column line.
  68                 http://www.alldatasheet.com/datasheet-pdf/pdf/27373/TI/SN74LS145D.html
  69     BU9831      Non-volatile electronic potentiometer: for calibration?
  70                 http://www.alldatasheet.com/datasheet-pdf/pdf/36387/ROHM/BU9831.html
  71     TP1683/4    Capacitive Sensing controller: no datasheet available.
  72
  73     (HHKB_keyswitch.jpg)
  74
  75     Topre original chip?
  76     (HHKB_TP1684.jpg)
  77
  78
  79 Two PCBs are connected by 15 lines. Vcc and GND use 3 lines each, other 9 lines are for keyboard signaling.
  80
  81     Keyswitch PCB connector                                 Teensy++ pins
  82     -------------------------------------------------------------------------------
  83      1  Vcc(5V)                                             5V
  84      2  Vcc(5V)
  85      3  Vcc(5V)
  86      4  TP1684    KEY: Low(0) when key pressed              PE6 input(with pullup)
  87      5  TP1684    KEY_PREV: assert previous key state???    PE7 output
  88      6  HC4051    A(bit0) select 8 rows(0 to 7)             PB0 output
  89      7  HC4051    B(bit1)                                   PB1 output
  90      8  HC4051    C(bit2)                                   PB2 output
  91      9  LS145     A(bit0) select 8 columns(0 to 7)          PB3 output
  92     10  LS145     B(bit1)                                   PB4 output
  93     11  LS145     C(bit2)                                   PB5 output
  94     12  LS145     D(enable) Low(0) enable selected column   PB6 output
  95     13  GND
  96     14  GND
  97     15  GND                                                 GND
  98
  99     (HHKB_connector.jpg)
 100
 101
 102 Keyswitch matrix
 103 ----------------
 104 60 keyswitches in 8*8 matrix. It is ghost-free and bounce-free.
 105
 106   COL 0     1       2       3       4       5       6       7
 107 ROW ---------------------------------------------------------------
 108   0|  2     q       w       s       a       z       x       c
 109   1|  3     4       r       e       d       f       v       b
 110   2|  5     6       y       t       g       h       n       _NONE_
 111   3|  1     Esc     Tab     Control LShift  LAlt    LMeta   Space
 112   4|  7     8       u       i       k       j       m       _NONE_
 113   5|  \     `       Delete  Return  Fn      RShift  RAlt    RMeta
 114   6|  9     0       o       p       ;       l       ,       _NONE_
 115   7|  -     +       ]       [       '       /       .       _NONE_
 116
 117
 118 Matrix diagram:
 119              +-------------------------+-+-+-+-+-+-+-+     Vcc
 120              |bias control?            - - - - - - - -     ---
 121              |                  3.9K*8 R R R R R R R R      |
 122     +--------^+      +--------+        - - - - - - - -      |
 123     |        2|      | HC4051 <0-------|-|-|-|-|-|-|-|--|R|-+
 124     |         |capa. |        <1-------|-|-|-|-|-|-|-|--|R|-+
 125     | TP1684  |sense |        <2-------|-|-|-|-|-|-|-|--|R|-+
 126     |       11<------|        <3-------|-|-|-|-|-|-|-|--|R|-+
 127     |         |      |        <4-------|-|-|-|-|-|-|-|--|R|-+
 128     |         |      |        <5-------|-|-|-|-|-|-|-|--|R|-+
 129     |         <-+    |        <6-------|-|-|-|-|-|-|-|--|R|-+
 130     |   1   4 | |    |        <7-------|-|-|-|-|-|-|-|--|R|-+
 131     +---V---^-+ |    +-^-^-^--+        0 1 2 3 4 5 6 7  33K*8
 132        KEY PREV |      A B C         +-----------------+
 133         |   | +-^----+ | | |         |      LS145      |
 134     Vcc |   | |BU9831| | | |         +-^--^--^--^------+
 135     --- |   | +------+ | | |           A  B  C  D   +------+
 136      |  |   |          | | |           |  |  |  |   |      |
 137     1-3 4   5          6 7 8           9 10 11 12 13-15    |
 138     +--------------------------------------------------+   |
 139     |                connector                         |  ---
 140     +--------------------------------------------------+  GND
 141                     to controller
 142
 143
 144 Signals charts:
 145     While pressing space bar, watched HHKB original controller signals by logic analyzer.
 146     Row and column is looping between 0-7 each for selecting a key.
 147     A key is scaned every about 15ms, so scan rate is 66Hz.
 148
 149     (HHKB_chart1.jpg)
 150
 151     Space bar locate at ROW:3 COL:7. A key is selected by HC4051(C,B,A) and LS145(C,B,A).
 152     Key state can be read on TP1684(4/KEY) while asserting low on LS145(D).
 153
 154     Usage of TP1684(5) is not clear. Controller seemed to output previous key state on this line.
 155     However key state can be read without using this signal.
 156
 157     (HHKB_chart2.jpg)
 158
 159
 160 Matrix scan pseudo code:
 161     for (row: 0-7) {
 162         SELECT_ROW(row);        // set HC4051(A,B,C)
 163
 164         for (col: 0-7) {
 165             SELECT_COL(col);    // set LS145(A,B,C)
 166
 167             _delay_us(40);
 168
 169             if (prev_key_state(row, col)) {
 170                 KEY_PREV_ON;
 171             }
 172
 173             _delay_us(7);
 174
 175             ENALBLE_COL();      // set LS145(D) to low
 176
 177             _delay_us(10);
 178
 179             if (KEY == 0) {     // read TP1684(KEY)
 180                 // key pressed
 181             } else {
 182                 // not pressed
 183             }
 184
 185             KEY_PREV_OFF;
 186             UNALBLE_COL();      // set LS145(D) to high
 187
 188             _delay_us(150);
 189         }
 190     }
 191
 192
 193 Keymap layers
 194 -------------
 195 Followings are added layers with additional Fn keys.
 196
 197 see keymap.c
 198
 199 EOF