NOTOC 15 PIN D-SUB FEMALE at the computer
15 PIN D-SUB MALE at the joystick cable
|Joystick 1 - X
|Joystick 1 - Y
|Joystick 2 - X
|Ground (shared with MIDI_OUT, see PC MIDI + game port)
|Joystick 2 - Y
|+5 VDC (shared with MIDI_IN, see PC MIDI + game port)
These pins are analog inputs and must be between 0 and 5 volts, 0 volts represents 0 (00000000 in binary) and 5 volts represents 255 (11111111 in binary). When a digital joystick is used, they generaly send a 2.5 volts signal when no buttons is pressed, go down to 0 volts when the up or left button is pressed and 5 volts when the down or right button is pressed.
These pins are TTL level signals, they are normally high at logical level 1 and when a button is pressed they go low to logical level 0. Note: Direction is Computer relative Joystick.
Types of joystick and actual connection to the port
The original joystick on the PC was an analog joystick, wich is composed of two fire buttons and two potentiometers for each axis (X and Y). The potentiometers used on this type of joystick are linear type with a value of 100 k ohms, and are wired as in figure 1. Figure 1: ANALOG JOYSTICK
A second joystick type started in the early 80’s, it was based on a digital circuit, it replaced the potentiometers with regular digital (on/off) switches, it was also known as an atari style joystick. And when Nintendo came out with the know well known joypad many companies like Gravis came out with PC joypads. These types of joysticks pretty much work all the same and are typically wired as in figure 2. Figure 2: DIGITAL JOYSTICK
The optional part of the above figure should only be connected when a four button joystick is required. If a second joystick is to be connected to the same port, a two button joystick should be used, because the 3rd and 4th buttons are connected to the 1st and 2nd button of the second joystick. If the joystick used has a 3rd or even a fourth button, you could also add a rapid fire repeater to it. An common way to add this feature, if you have the room for it, is to use a simple circuit like in figure 3, it uses a 555 timer to witch is enabled when you press the button, and sends pulses at about 400Hz to the computer input, you could even make an inline box adapter that would add auto repeat fire to the existing buttons of your joystick by simply feeding the signal from the joystick to the 555 timer and sending the output of it to the computer. Figure 3: AUTO REPEAT FIRE
When a second joystick is to be used on a single port, you must first have a port that allows two joysticks to be connected to it and secondly you need a special Y adapter cable witch can be purchased at most computer resellers. For those of you who would like to build there own cable the connections to make one are explained in figure 4. Figure 4: Y CABLE JOYSTICK ADAPTER
This is one way to configure a second joystick and is probably the best way to do it, some people or manufacturers will replace the two blue wires connected to pins 4 & 5 of the Joystick 2 connector and will connect them to pin 12 from the computer and the red wire connected to pin 8 of the joystick 2 connector and will connect it to pin 15 from the computer. This is ok, but if you have a midi enabled connector (mostly found on soundcards), the second way might not work, it could disable the soundcard all together, because these pins (12 & 15) are used for midi input and output. So to be on the safe side, the wiring diagram in figure 4 is probably the safest way to go. If you have already bought a cable and it doesn’t seem to work wright, it might be that the cable is wired to pins 12 & 15. One way to overcome this problem is to build a special adapter wired like in figure 5, this adapter reroutes the two pins to from pin 5 & 9 and thus isolates the two midi pins. Note that on a 3 axis joystick(like with a throttle) the Z axis would go to pin 13 (Y2). The 4th axis, the U axis (like for rudder pedals), would go in pin 11 (X2). Figure 5: MIDI PIN ISOLATOR ADAPTER