Reading MD3 Joypad: Difference between revisions
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=Code= | =Code= | ||
<syntaxhighlight> | <syntaxhighlight lang="asm"> | ||
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 | | |||
</syntaxhighlight> | </syntaxhighlight> | ||
[[Category:MegaDrive]] | [[Category:MegaDrive]] | ||
[[Category:Code]] | [[Category:Code]] |
Latest revision as of 11:53, 19 January 2017
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 |
| |||||||||||||||||
0 |
|
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 |