Details
All the buttons can't be read at once. There is a multiplexer inside the control pad.
Reading the 3 buttons pad consist of 5 steps :
- Set the direction of pin 6 to output and all others to input.
- Set TH (pin6) to 1.
- Read the first part of the buttons (UP,DOWN,LEFT,RIGHT,B,C)
- Switch the outputs in the control pad by setting TH (pin6) to 0.
- Read the second part of the buttons (A,START)
| TH State
|
Data
|
| 1
|
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
0 |
TH | C | B | RIGHT | LEFT | DOWN | UP |
|
| 0
|
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Def |
0 |
TH | START | A | 0 | 0 | DOWN | UP |
|
Code
moveq #0, d0
moveq #0, d1
move.b #0x40, (0xA10009) | Set direction
move.b #0x40, (0xA10003) | TH = 1
nop
nop
move.b (a0), d0 | d0.b = X | 1 | C | B | R | L | D | U |
andi.b #0x3F, d0 | d0.b = 0 | 0 | C | B | R | L | D | U |
move.b #0x0, (0xA10003) | TH = 0
nop
nop
move.b (0xA10003), d1 | d1.b = X | 0 | S | A | 0 | 0 | D | U |
andi.b #0x30, d1 | d1.b = 0 | 0 | S | A | 0 | 0 | 0 | 0 |
lsl.b #0x2, d1 | d1.b = S | A | 0 | 0 | D | U | 0 | 0 |
or.b d1, d0 | d0.b = S | A | C | B | R | L | D | U |