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.
8 This is just a proof of concept for replacing controller of HHKB, not a complete firmware.
10 My prototype firmware source tree is here:
11 branch: hhkb(http://github.com/tmk/tmk_keyboard/tree/hhkb)
12 This firmware is a port of my previous project:
13 HHKB style Mod(http://geekhack.org/showwiki.php?title=Island:11930)
15 Teensy++/Teensy(http://www.pjrc.com/teensy/)
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)
25 * unavailability of Teensy++/Teensy(because of PS3 cracking boom?)
30 * mouse keys for minimum mouse operation(never comfortable for normal use)
31 * and more...(in the future)
33 Any suggestions or ideas are welcome.
37 My HHKB is just "Professional". This means followings may not be applied to "Professional2".
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.
46 Angled USB mini B adapter is used to install Teensy++ laterally.
49 Bread baord cables used for connect Teensy++.
51 (connector_contact.jpg)
56 HHKB pro has two PCBs and some chips.
59 M38K07M4 Renesas MCU with USB function
60 http://documentation.renesas.com/eng/products/mpumcu/rej03b0192_38k0ds.pdf
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 TP1684 Capacitive Sensing controller: no datasheet available.
79 Two PCBs are connected by 15 lines. Vcc/GND uses 3 lines each, 9lines for keyboard signaling.
81 Keyswitch PCB connector Teensy++ pins
82 -------------------------------------------------------------------------------
86 4 TP1684 KEY: Low(0) when key pressed PE6 input(with pullup)
87 5 TP1684 unknown:how to use PE7 input(with pullup)
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
104 60 keyswitches in 8*8 matrix. ghost free. bounce free.
107 ROW ---------------------------------------------------------------
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_
119 +-------------------------+-+-+-+-+-+-+-+ Vcc
120 |bias control? - - - - - - - - ---
121 | 3.9K*8 R R R R R R R R |
122 +--------^+ +--------+ - - - - - - - - |
123 | TP 1684 | | HC4051 <0-------|-|-|-|-|-|-|-|--|R|-+
124 | |capa. | <1-------|-|-|-|-|-|-|-|--|R|-+
125 | |sense | <2-------|-|-|-|-|-|-|-|--|R|-+
126 | <------| <3-------|-|-|-|-|-|-|-|--|R|-+
127 | | | <4-------|-|-|-|-|-|-|-|--|R|-+
128 | | | <5-------|-|-|-|-|-|-|-|--|R|-+
129 | |calib.| <6-------|-|-|-|-|-|-|-|--|R|-+
130 | <-+? | <7-------|-|-|-|-|-|-|-|--|R|-+
131 +---V-----+ | +-^-^-^--+ 0 1 2 3 4 5 6 7 33K*8
132 KEY ??? | 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 +--------------------------------------------------+ |
140 +--------------------------------------------------+ GND
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.
151 Space bar locate at ROW:3 COL:7. Key are 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 Usage of TP1684(5) is unknown. Key state can be read without using this signal.
158 Matrix scan pseudo code:
160 SELECT_ROW(row); // set HC4051(A,B,C)
163 SELECT_COL(col); // set LS145(A,B,C)
167 ENALBLE_COL(); // set LS145(D) to low
171 if (KEY == 0) { // read TP1684(KEY)
182 Followings are added layers with additional Fn keys. They are not final decision.