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Internal of HHKB pro
=====================
HHKB pro has MCU and some chips on separate two PCBs.
Controller PCB
--------------
M38K07M4 Renesas MCU with USB function
http://documentation.renesas.com/eng/products/mpumcu/rej03b0192_38k0ds.pdf
(HHKB_controller.jpg)
Keyswitch PCB
-------------
HC4051 Analog Multiplexer: select a row line.
http://www.ti.com/lit/ds/schs122j/schs122j.pdf
LS145 BCD Decoder: select a column line.
http://www.ti.com/lit/ds/symlink/sn74ls145.pdf
BU9831 Non-volatile electronic potentiometer: for calibration?
https://www.spezial.com/doc/rohm-a/bu9831.pdf
TP1683/4 Capacitive Sensing controller: no datasheet available.
(HHKB_keyswitch.jpg)
Topre original chip?
(HHKB_TP1684.jpg)
Connector Cable
---------------
Two PCBs are connected by 15 lines(13 in case of Pro2).
Vcc and GND use 3(2) lines each, other lines are for keyboard signaling.
HHKB connector lines:
JP Pro2 Pro Function Description Teensy++ pins
--------------------------------------------------------------------------------------------
1 Vcc(5V) 5V
1 1 2 Vcc(5V) 5V
2 2 3 Vcc(5V) 5V
3 3 4 TP1684 KEY: Low(0) when key pressed PE6 input(with pullup)
4 4 5 TP1684 KEY_PREV: make threshold PE7 output
5 5 6 HC4051 A(bit0)\ PB0 output
6 6 7 HC4051 B(bit1) > select row 0-7 PB1 output
7 7 8 HC4051 C(bit2)/ PB2 output
8 8 9 LS145 A(bit0)\ PB3 output
9 9 10 LS145 B(bit1) > select column 0-7 PB4 output
10 10 11 LS145 C(bit2)/ PB5 output
11 11 12 LS145 D(enable) Low(0) enables selected column PB6 output
12 12 13 GND GND
13 13 14 GND GND
15 GND
14 HC4051(Z2) ~Enable of Z2 row0-7
15 HC4051(Z3) ~Enable of Z3 row8-15
NOTE: guessing pin5(KEY_PREV) may work for hysteresis of capacitive sensing.
NOTE: 1KOhm didn't work as pullup resistor on KEY. AVR internal pullup or 10KOhm resistor was OK.
NOTE: JP has two HC4051(Z2,Z3) and line 5, 6 and 7 are connected to both of them.
(HHKB_connector.jpg)
Keyswitch matrix
----------------
HHKB switch matrix is ghost-free and bounce-free.
Pro/Pro2(8x8):
COL 0 1 2 3 4 5 6 7
ROW ---------------------------------------------------------------
0| 2 q w s a z x c
1| 3 4 r e d f v b
2| 5 6 y t g h n _NONE_
3| 1 Esc Tab Control LShift LAlt LMeta Space
4| 7 8 u i k j m _NONE_
5| \ ` Delete Return Fn RShift RAlt RMeta
6| 9 0 o p ; l , _NONE_
7| - + ] [ ' / . _NONE_
JP(16x8):
COL 0 1 2 3 4 5 6 7
ROW ---------------------------------------------------------------
0| ESC TAB LFn LShift LCtrl
1| 4 E MuHKN C D
2| 3 W LAlt X S
3| 1 HHK
4|
5| 5 R V F
6| 2 Q LGui Z A
7| 6 T Space B G
8| 9 I Kana , K
9| 8 U Henkan M J
A| 7 Y N H
B| 0 O RAlt . L
C| BS Right RShift Enter
D| \ [ Down Up ]
E| - P RFn / ;
F| ~ @ Left Ro :
Matrix diagram:
Pro/Pro2:
+-------------------------+-+-+-+-+-+-+-+ Vcc
|bias control? - - - - - - - - ---
| 3.9K*8 R R R R R R R R |
+--------^+ +--------+ - - - - - - - - |
| 2| | HC4051 <0-------|-|-|-|-|-|-|-|--|R|-+
| |capa. | <1-------|-|-|-|-|-|-|-|--|R|-+
| TP1684 |sense | <2-------|-|-|-|-|-|-|-|--|R|-+
| 11<------| <3-------|-|-|-|-|-|-|-|--|R|-+
| | | <4-------|-|-|-|-|-|-|-|--|R|-+
| | | <5-------|-|-|-|-|-|-|-|--|R|-+
| <-+ | <6-------|-|-|-|-|-|-|-|--|R|-+
| 1 4 | | | <7-------|-|-|-|-|-|-|-|--|R|-+
+---V---^-+ | +-^-^-^--+ 0 1 2 3 4 5 6 7 33K*8
KEY PREV | A B C +-----------------+
| | +-^----+ | | | | LS145 |
Vcc | | |BU9831| | | | +-^--^--^--^------+
--- | | +------+ | | | A B C D +-------+
| | | | | | | | | | | |
1-3 4 5 6 7 8 9 10 11 12 13-15 Pro |
1-2 3 4 5 6 7 8 9 10 11 12-13 Pro2|
+--------------------------------------------------+ |
| connector | ---
+--------------------------------------------------+ GND
JP:
+-----------------------------+-+-+-+-+ Vcc
|bias control? - - - - - ---
| 3.9K*5 R R R R R |
+--------^+ +--------+ - - - - - |
| | | HC4051 <0-----------|-|-|-|-|----|R|-+
| |capa. | Z2 <1-----------|-|-|-|-|----|R|-+
| TP1684 |sense | <2-----------|-|-|-|-|----|R|-+
| <---+--| <3-----------|-|-|-|-|----|R|-+
| | | | <4-----------|-|-|-|-|----|R|-+
| | ~En| <5-----------|-|-|-|-|----|R|-+
| | +----> <6-----------|-|-|-|-|----|R|-+
| | | | | A B C <7-----------|-|-|-|-|----|R|-+
+---V---^-+ | | +-^-^-^--+ | | | | | |
KEY PREV | | | | | | | | | | |
| | | | +--------+ | | | | | |
| | | | | HC4051 <8-----------|-|-|-|-|----|R|-+
| | | | | Z3 <9-----------|-|-|-|-|----|R|-+
| | | +--| <A-----------|-|-|-|-|----|R|-+
| | | | <B-----------|-|-|-|-|----|R|-+
| | | | <C-----------|-|-|-|-|----|R|-+
| | | ~En| <D-----------|-|-|-|-|----|R|-+
| | | +-> <E-----------|-|-|-|-|----|R|-+
| | | | | A B C <F-----------|-|-|-|-|----|R|-+
| | | | +-^-^-^--+ 0 1 2 3 4 5 6 7 33K*8
| | | | | | | +-----------------+
| | | | | | | | LS145 |
Vcc | | | | | | | +-^--^--^--^------+
--- | | | | | | | A B C D +-------+
| | | | | | | | | | | | | |
1-2 3 4 14 15 5 6 7 8 9 10 11 12-13 |
+--------------------------------------------------+ |
| connector | ---
+--------------------------------------------------+ GND
Signals charts
--------------
While pressing space bar, watched HHKB original controller signals by logic analyzer.
Row and column is looping between 0-7 each for selecting a key.
A key is scaned every about 15ms, so scan rate is 66Hz.
(HHKB_chart1.jpg)
Space bar locate at ROW:3 COL:7. A key is selected by HC4051(C,B,A) and LS145(C,B,A).
Key state can be read on TP1684(4/KEY) while asserting low on LS145(D).
Usage of TP1684(5) is not clear. Controller seemed to output previous key state on this line.
However key state can be read without using this signal.
(HHKB_chart2.jpg)
5us after setting colA-C
colA _~~~~~~~~~~~~~~~~~~
prev _~~~~_____ 20us if previous key state is low
colD ~~~__~~~~~ 10us column enabled
key ~~~____~~~ 22us hold state of the key
prev ____~~~~__________ 20us(JP)/17us(Pro2)
key ~~~~~~_____~~~~~~~ 22us
colD ~~~~~~__~~~~~~~~~~ 10us(LS175)
colC ____~~~~____~~~~ 550/410us(JP)
colB __~~__~~__~~__~~ 200/210us(JP)
colA _~_~_~_~_~_~_~_~ 100/110us(JP) 200/210us(Pro2)
0123456701234567 selected column
rowC ____~~~~____~~~~ 3.8/3.8ms(JP) S2 of HC4051
rowB __~~__~~__~~__~~ 1.9/1.9ms(JP) S1 of HC4051
rowA _~_~_~_~_~_~_~_~ 1.0/1.0ms(JP) S0 of HC4051
0123456701234567 selected row(Pro/Pro2)
0123456789ABCDEF selected row(JP)
rowEn0 ________~~~~~~~~ 7.7/7.7ms ~Enable of Z2 HC4051(JP only)
rowEn1 ~~~~~~~~________ 7.7/7.7ms ~Enable of Z3 HC4051(JP only)
NOTE: JP scans twice fast as Pro2 does. So Pro2 scan 8x8 matrix in 15.4ms while JP can 16x8 in that time.
Matrix scan pseudo code
-----------------------
for (row: 0-7) {
SELECT_ROW(row); // set HC4051(A,B,C)
for (col: 0-7) {
SELECT_COL(col); // set LS145(A,B,C)
_delay_us(40);
if (prev_key_state(row, col)) {
KEY_PREV_ON;
}
_delay_us(7);
ENALBLE_COL(); // set LS145(D) to low
_delay_us(10);
if (KEY == 0) { // read TP1684(KEY)
// key pressed
} else {
// not pressed
}
KEY_PREV_OFF;
UNALBLE_COL(); // set LS145(D) to high
_delay_us(150);
}
}
EOF
|
