Vcc and GND use 3(2) lines each, other lines are for keyboard signaling.
HHKB connector lines:
- JP Pro2 Pro Function Description Teensy++ pins
+ JP Pro2 Pro Function Description TMK pin usage
--------------------------------------------------------------------------------------------
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
+ 3 3 4 TP1684 ~KEY: Low(0) when key is pressed PD7 input(with pullup)
+ 4 4 5 TP1684 HYS: High(1) when key is pressed PB7 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
+ 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
+ 14 HC4051(Z2) ~Enable of Z2 row0-7 PC6
+ 15 HC4051(Z3) ~Enable of Z3 row8-15 PC7
- NOTE: guessing pin5(KEY_PREV) may work for hysteresis of capacitive sensing.
+ NOTE: Probably HYS changes threshold for upstroke and makes hysteresis in the result.
+ NOTE: HYS should be given High(1) when previous KEY state is Low(0).
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.
|bias control? - - - - - - - - ---
| 3.9K*8 R R R R R R R R |
+--------^+ +--------+ - - - - - - - - |
- | 2| | HC4051 <0-------|-|-|-|-|-|-|-|--|R|-+
- | |capa. | <1-------|-|-|-|-|-|-|-|--|R|-+
+ | 3| | HC4051 <0-------|-|-|-|-|-|-|-|--|R|-+
+ | DIL-20 |capa. | <1-------|-|-|-|-|-|-|-|--|R|-+
| TP1684 |sense | <2-------|-|-|-|-|-|-|-|--|R|-+
- | 11<------| <3-------|-|-|-|-|-|-|-|--|R|-+
+ | 20<------| <3-------|-|-|-|-|-|-|-|--|R|-+
| | | <4-------|-|-|-|-|-|-|-|--|R|-+
| | | <5-------|-|-|-|-|-|-|-|--|R|-+
- | <-+ | <6-------|-|-|-|-|-|-|-|--|R|-+
- | 1 4 | | | <7-------|-|-|-|-|-|-|-|--|R|-+
+ >5~EN <-+ | <6-------|-|-|-|-|-|-|-|--|R|-+
+ | 2 4 | | | <7-------|-|-|-|-|-|-|-|--|R|-+
+---V---^-+ | +-^-^-^--+ 0 1 2 3 4 5 6 7 33K*8
- KEY PREV | A B C +-----------------+
+ KEY HYS | A B C +-----------------+
| | +-^----+ | | | | LS145 |
Vcc | | |BU9831| | | | +-^--^--^--^------+
--- | | +------+ | | | A B C D +-------+
|bias control? - - - - - ---
| 3.9K*5 R R R R R |
+--------^+ +--------+ - - - - - |
- | | | HC4051 <0-----------|-|-|-|-|----|R|-+
+ | 3| | HC4051 <0-----------|-|-|-|-|----|R|-+
| |capa. | Z2 <1-----------|-|-|-|-|----|R|-+
| TP1684 |sense | <2-----------|-|-|-|-|----|R|-+
- | <---+--| <3-----------|-|-|-|-|----|R|-+
+ | 20<---+--| <3-----------|-|-|-|-|----|R|-+
| | | | <4-----------|-|-|-|-|----|R|-+
| | ~En| <5-----------|-|-|-|-|----|R|-+
- | | +----> <6-----------|-|-|-|-|----|R|-+
- | | | | | A B C <7-----------|-|-|-|-|----|R|-+
+ >5~EN | +----> <6-----------|-|-|-|-|----|R|-+
+ | 2 4 | | | | A B C <7-----------|-|-|-|-|----|R|-+
+---V---^-+ | | +-^-^-^--+ | | | | | |
- KEY PREV | | | | | | | | | | |
+ KEY HYS | | | | | | | | | | |
| | | | +--------+ | | | | | |
| | | | | HC4051 <8-----------|-|-|-|-|----|R|-+
| | | | | Z3 <9-----------|-|-|-|-|----|R|-+
+--------------------------------------------------+ |
| connector | ---
+--------------------------------------------------+ GND
+
+TP1684-5(~EN) pin is connected with LS145-D/Connector-11.
Signals charts
(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).
+ Key state can be read on TP1684(4) while asserting low on LS145(D).
(HHKB_chart2.jpg)
0123456701234567 selected column
3) Wait 5us after column select, then set prev, strobe colD to spit out key status and read it.
- prev _~~~~_____ 20us if previous key state is low
+ hys _~~~~_____ 20us if previous key state is low
colD ~~~__~~~~~ 10us strobe
key ~~~____~~~ 22us indicates current state of the key