PC Gameport+MIDI connector

Pin	Name	Dir	Description
1	+5V		+5 VDC
2	/B1		Button 1
3	X1		Joystick 1 - X
4	GND		Ground
5	GND		Ground
6	Y1		Joystick 1 - Y
7	/B2		Button 2
8	+5V		+5 VDC
9	+5V		+5 VDC
10	/B4		Button 4
11	X2		Joystick 2 - X
12	MIDITXD		MIDI Transmit
13	Y2		Joystick 2 - Y
14	/B3		Button 3
15	MIDIRXD		MIDI Receive

About MIDI Signals

How this document describe signals

MIDI Signals are like ASM instructions :
First a byte gives the instruction, if there is parameters, they follow the instruction byte using data bytes.

For exemple, "Note off event (Key, Velocity)" for channel 0 will be send as "Note off event" byte, then Key data byte, then Velocity data byte: "1000 0000 - 0kkk kkkk - 0vvv vvvv"
where kkkkkkk is the Key value and vvvvvvv is the Velocity value.
Data are always 7 bits, to allow the 0 beginning the data byte, when a parameter need more than 7 bits, it uses 2 data bytes, again like in ASM: LSB followed by MSB.

Bytes table

Channel Signals

The 4 highest bits of a channel status byte is the instruction, the 4 lowest ones is the channel number.

Note off event (key, velocity)
Note on event (key, velocity)
Polyphonic key pressure (key, after-touch)
Control change (command address, command value)
Program change (program number)
Channel pressure (after-touch)
Pitch wheel change (value lsb, value msb)

System Exclusive

These two instructions are used to send special instructions to a MIDI device, the instruction is made of a 2 bytes header, followed by data block(s) (as many as needed) and then finish by an end of block byte.

System Exclusive Header + Data (Identification code) + Data block(s) + System Exclusive End of block

System Real Time

Instructions for synchronisation and rythm boxes control, send for all channels.

Timing Clock In Play
This clock is send while the system is in "play" mode.
There are 24 clock impulsions for 1 black note.

Measure End
Replace the Timing Clock In Play signal at the end of every measure.

Start From 1st Measure
This signal is send when the master "play" key is pressed.
The first Timing Clock In Play must be send in the next 5ms following this signal.

Continue Start
This signal is send directly when the master "continue" key is pressed.
The next Timing Clock In Play must be send in the next 5ms following this signal.

Timing Clock In End
This signal is send when the master is in wait-mode and is used to lock a PLL during a pause.

Active Sensing
no information available.

System Common

Measure Information (measure number lsb, measure number msb)
Song Select (song number)
Tune Request

System Reset

System Reset
Restart the whole system.

Parameters

Channel
Channel number from 0 to 15.

Key
Key number from 0 to 127, the central A is always number 60.

Velocity
Velocity from 0 to 127 (0=Note off).
If the keyboard doesn"t have velocity, 64 is send as default.

After touch
After-touch from 0 to 127.

Command address
Address from 0 to 127.
Except for the "Pitch bender", which is 0, there is no specification for these.

Command value
For controllers, from 0 to 127.
For switches, 0=off, 127=on (other ore ignored).

Program number
Program number from 0 to 127.

Identification code
Society code from 0 to 127.

Note: Direction is Computer relative Joystick.
Note: Use 100 kohm resistor.