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A-PAC analog gamepad interface

32 Button Interface which can also handle up to 4 pots.

The A-PAC is an analog/digital interface which emulates two gamepads. It can be used for buttons only, or various combinations of buttons and analog potentiometer (pot) devices. It can be used in any of these configurations::
32 Buttons
One analog axis and 30 buttons
Two analog axes and 28 buttons
Three analog axes and 26 buttons
Four analog axes and 24 buttons
Inputs auto-detect whether pots or buttons.are connected. One button (Start1) is a shift button which enables another set of shifted buttons. This gives a maximum of 62 logical buttons.


  • Emulates not one but TWO gamepad devices. Most gaming apps will work“out of the box” since they will see one gamepad for each player.
  • Shift function. The “Start1” button input on each side be haves as a regular button but also when pressed changes the buttons in use to numbers13-28.
  • Easy connection via screw connectors. Inputs are labelled for convenience but are universal.
  • Can use 1,2,3 or 4 analog axes, or the directions can be digital,using buttons.
  • All button inputs (including any direction inputs used with buttons)are fully de bounced with individual state counters for maximum key roll-over performance.
  • Logical board layout with one gamepad device on each side of the board.
  • One-to-one-one mapping means that connecting pots or buttons for the player 1 and 2 directions is easy. You can make a direct swap from direction switches to direction pots.
  • Super-fast Full-Speed USB technology..
  • 12-Bit analog to digital conversion.
  • Can use any pot values and different value pots can be used on each side of the board.
  • Precision analog conversion is immune to variations in pot resistance, owing to the ratio comparison method used, so no calibration of the center position will normally be needed for analog joysticks.
  • Uses interrupt triggering rather than polling for maximum accuracy and speed.
  • As well as using analog joysticks, any other pot devices can be used such as pedals, steering wheels etc.
  • As many boards as required can be added for more devices. Perfect for large flight-sim panels.
  • Shift function adds extra buttons. Also ideal for flight-sim panels which require a large number of control-type buttons.
  • No drivers needed. Windows recognizes two gamepads, Device #1 and#2.

    INSTALLATION The picture below shows wiring of the maximum number of pots, ie 4pots. It also shows an example 4 switches. Note that not all four pot positions need to be used for pots. You can connect buttons instead to any input. The direction of the pot control depends on the wiring of the two outer connections on the pot. If the pot works "backwards",then swap these over. Note Mame can also be configured to reverse analog control directions.
    A-PAC step1
    The "Start1" input changes the selected buttons to the shifted set, buttons 13-28 in Windows.This behaves in exactly the same way as the I-PAC shift button. All the other inputs are ordinary buttons.

    If you are not using analog controls, but using a regular micro-switch joystick, simply connect the 4 joystick switches to UP, DOWN, LEFT and RIGHT in the same way as the I-PAC boards.
    The button assignment is shown below, which is a screen capture from Control Panel, Game Devices in Windows.Open Control Panel, Game Devices. You will see two A-PAC Gamepad devices shown.Select each one and check for correct operation. The top one in the list is the player 1 side, the lower one is player 2. This capture below shows the display for ONE SIDE of the board , ie one gamepad device.The button display for the other device is identical.
    gamepad devices
    The above controls are duplicated for the Player 2 side of the board
    If you are using controls which don't cover the entire range of travel of the pot, you will need to calibrate the control. All you need to do is click on "Control Panel", "Game Controllers", and then highlight the upper or lower entry for "A-PAC Interface", and follow the instructions. This will ensure that a full movement of the control device corresponds to a full movement in the game.
    "Trick" Calibration.
    You might want to calibrate so that analog control produces full movement in the game over a small movement of the control. You can easily do this. During the calibration process, when it asks you to move the control to the limits of movement, if you only move it to, for example 50% of the travel, this will be logged as the full-travel position, so you will get a full game movement over 50% of the actual control motion.
    Other Settings
    MAME has a setting for "Joystick Dead Zone". This is useful when you are using an analog control in a digital game, as you can tweak the "travel" of the control, ie how far you have to move it before it registers as an emulated switch press.

    Using with MAME
    To use this device with MAME,all you need to do is enable joystick support in MAME.INI. The play buttons and joysticks are then automatically assigned in MAME because this device is seen as two gamepads which MAME expects. You may need to assign COIN and START buttons. If you start with a digital (switch) joystick and then re-wire to analog stick, there is no need to change any settings.

  • I am using a driving control such as a pedal, this has no "left,right". How do I connect it?
    You can simply wire the ends of the pot to"left, right" or to "up, down" and then in the game, assign the control to suit. Normally you select the direction you want to assign, and then move the control (pedal) in that direction to set the control. MAME references analog axes as "+" and "-" to determine the direction. For this purpose, "+" is equivalent to "UP" or "RIGHT" and "-" is equivalent to "DOWN" or"LEFT".
  • Can I use more that 4 axes on one board?
    With this board 4 analog axes is the maximum, but if there is a requirement for more , check out the U-HID series of boards
  • Can I connect analog and digital controls to the same input?This will work but we don't recommend it because switch-specific functionality such as de-bounce will not be enabled. Better to use a different input for switches.
  • Why does the PCB have "I-PAC" printed on it?
    This is a universal board which was designed for several variants, and is used for our I-PAC VE product. This keeps costs down .
  • What software can I use?
    You can use any O/S and game which is compatible with a gamepad. device.
  • What types of control can I use?
    For analog you can use any controls which contain potentiometers. These include steering wheels,pedals, analog joysticks, flight yokes etc. You don't need to stick to the markings on the board but can wire to any convenient analog axis and configure the game to match. All 32 inputs will also accept switch controls such as pushbuttons, joysticks.