Dreamcast Programming - Controllers

Controllers

The Dreamcast Controller (HKT-7700) has five buttons, one directional
pad, one analogue joystick, and two analogue triggers.  In order to be
able to provide feedback for all these actuators, the controller speaks
with the Dreamcast unit using a serial protocol.  The serial connection
is bi-directional, which allows the Dreamcast to upload data into
docked VMS units.

All the logic of the controller is contained in a single chip (IC1)
which is labled as follows:

+--------------+
| SEGA         |
| E2 MAPLE BUS |
| 315-6125-AB  |
| 841A2A20     |
+--------------+

Male connector pinout:

[ 5 3 1 ]
[  4 2  ]

The plate on top of the connector is for the cable shield.  It is
internally connected to pin 3 (GND).

Internal connector inside controller pinout:

[1 2 3 4 5]

1	red	serial data
2	blue	+5V
3	black	GND
4	green	sense (connected to GND inside controller/keyboard)
5	white	serial data

Gamepad Condition structure

The current state of a gamepad is queried with the Get condition
request.  The condition stucture for the Controller function code
($001) is as follows:

int16 buttons	; digital buttons bitfield (little endian)
int8 rtrigger	; right analogue trigger (0-255)
int8 ltrigger	; left analogue trigger (0-255)
int8 joyx	; analogue joystick X (0-255)
int8 joyy	; analogue joystick Y (0-255)
int8 joyx2	; second analogue joystick X (0-255)
int8 joyy2	; second analogue joystick Y (0-255)

The buttons bitfield contains zeroes for pressed buttons, and ones for
unpressed buttons.

0	C
1	B
2	A
3	START
4	UP
5	DOWN
6	LEFT
7	RIGHT
8	Z
9	Y
10	X
11	D
12	UP 2
13	DOWN 2
14	LEFT 2
15	RIGHT 2

Gamepad Function data bitfield

The function_data for the Controller function code is a bitfield
describing which controls are present on the particular device (zero =
not present, one = present):

0	C
1	B
2	A
3	START
4	UP
5	DOWN
6	LEFT
7	RIGHT
8	Z
9	Y
10	X
11	D
12	UP 2
13	DOWN 2
14	LEFT 2
15	RIGHT 2
16	Analog R trigger
17	Analog L trigger
18	Analog horizontal
19	Analog vertical
20	Analog horizontal 2
21	Analog vertical 2