Keypad
The WonderSwan SoC features a 4 by 3 keypad matrix.
Scanning
Scanning is done via writing to and reading from port $B5.
7 bit 0 ---- ---- .iii oooo ||| ++++- Output rows (0-3) +++------ Input rows (4-6)
The standard procedure is to read rows 4, 5 and 6 in order, shifting their values into one twelve-bit mask like so:
15 bit 0 ---- ---- ---- ---- .... 4444 5555 6666
Typical keypad scanning implementations introduce a delay between writing to and reading from the matrix, allowing the scanned values to stabilize. For example, one can use the DAA opcode for doing so.
Startup override
On startup, the boot ROM checks whether or not certain output rows are forced high when all input rows are disabled. This triggers a startup override:
- Input row 0 - jump to 4000:0000,
- Input row 1 - jump to 4000:0010.
As this override is done before boot ROM lockout, it can be used to dump the boot ROM.
Keypad arrangement
WonderSwan
Layout
Y1
Y4 Y2
Y3
X1
X4 X2 A
X3 Sound Start Power B
(St)
Sound and Power buttons are not exposed directly to software.
Matrix
Bit O 3 2 1 0
I | | | |
| | | |
4--- Y4 - Y3 - Y2 - Y1 -
| | | |
5--- X4 - X3 - X2 - X1 -
| | | |
6--- B - A - St ---+--
| | | |
Bit mask
15 bit 0
---- ---- ---- ----
.... yyyy xxxx bas.
|||| |||| ||+- Start
|||| |||| |+-- A
|||| |||| +--- B
|||| ++++----- X4, X3, X2, X1
++++---------- Y4, Y3, Y2, Y1
Pocket Challenge V2
Layout
Power
Esc
View
Up Clear
(Clr)
Lft Rgh Circle
(Crc)
Dwn Pass
(Pas)
The Power switch is not exposed directly to software.
Matrix
Bit O 3 2 1 0
I | | | |
| | | |
4--- Pas Crc --+-- Clr -
| | | |
5--- Rgh Esc --+- View -
| | | |
6--- Up - Dwn --+-- Lft -
| | | |
[1]
Bit mask
15 bit 0
---- ---- ---- ----
.... pc1C re1v ud1l
|| | || | || +- Left
|| | || | |+--- Down
|| | || | +---- Up
|| | || +------ View
|| | |+-------- Esc
|| | +--------- Right
|| +----------- Clear
|+------------- Circle
+-------------- Pass
