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-rw-r--r--hhkb/doc/HHKB.txt17
1 files changed, 13 insertions, 4 deletions
diff --git a/hhkb/doc/HHKB.txt b/hhkb/doc/HHKB.txt
index 3ca272c800..e9f41adab0 100644
--- a/hhkb/doc/HHKB.txt
+++ b/hhkb/doc/HHKB.txt
@@ -84,7 +84,7 @@ Two PCBs are connected by 15 lines. Vcc and GND use 3 lines each, other 9 lines
2 Vcc(5V)
3 Vcc(5V)
4 TP1684 KEY: Low(0) when key pressed PE6 input(with pullup)
- 5 TP1684 unknown:how to use PE7 input(with pullup)
+ 5 TP1684 KEY_PREV: assert previous key state??? PE7 output
6 HC4051 A(bit0) select 8 rows(0 to 7) PB0 output
7 HC4051 B(bit1) PB1 output
8 HC4051 C(bit2) PB2 output
@@ -148,9 +148,11 @@ Signals charts:
(HHKB_chart1.jpg)
- Space bar locate at ROW:3 COL:7. Key are selected by HC4051(C,B,A) and LS145(C,B,A).
+ 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 unknown. Key state can be read without using this signal.
+
+ 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)
@@ -162,7 +164,13 @@ Matrix scan pseudo code:
for (col: 0-7) {
SELECT_COL(col); // set LS145(A,B,C)
- _delay_us(50);
+ _delay_us(40);
+
+ if (prev_key_state(row, col)) {
+ KEY_PREV_ON;
+ }
+
+ _delay_us(7);
ENALBLE_COL(); // set LS145(D) to low
@@ -174,6 +182,7 @@ Matrix scan pseudo code:
// not pressed
}
+ KEY_PREV_OFF;
UNALBLE_COL(); // set LS145(D) to high
_delay_us(150);