Search for PC Game Joystick port technical clarification

Discussion in 'General Electronics Chat' started by rcarabaj, Sep 3, 2009.

  1. rcarabaj

    Thread Starter New Member

    Apr 10, 2005

    I have read the following specifications about PC Game Joystick Port:

    Pin Name Dir Description 1 +5V OUT +5 VDC 2 /B1 IN Button 1 3 X1 IN Joystick 1 - X 4 GND - Ground 5 GND - Ground 6 Y1 IN Joystick 1 - Y 7 /B2 IN Button 2 8 +5V OUT +5 VDC 9 +5V OUT +5 VDC 10 /B3 IN Button 3 11 X2 IN Joystick 2 - X 12 GND - Ground (shared with MIDI_OUT, see PC MIDI + game port) 13 Y2 IN Joystick 2 - Y 14 /B4 IN Button 4 15 +5V OUT +5 VDC (shared with MIDI_IN, see PC MIDI + game port) Axis signals

    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.

    I am a bit confused. :confused: I saw that´s usual Joysticks are connected using 100 Kohms potentiometers, between pins 1 - 3 or 1- 6 . Does the note above mean that I can put any 0-5 Volts source voltage and it will be accepted by the PC interface, and used as legal input ?.
    In others words, is the 100 Kohms specification one way to obtain a signal using the +5 Volts built-in provided by pin 1, but if required, there can be used other outlines ?

    I would appreciate any explanation.:rolleyes:
    My best regards.
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Your question is a bit hard to interpret. Joysticks use 100K potentiometers because it keeps current demands low. The A to D converter has a high enough input impedance that it does not load the signal from the X and Y axis pots. A 1K pot will work the same.

    The 0 - 5 volt signal you ask about will also work, as long as the grounds of the signal source and the computer's joystick port are tied together.