Mini-PAC Opti

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Integrated Switch/Joystick/Trackball/Spinner Interface with Wiring Harness

No more cutting/stripping/crimping!

Do you regularly build control panels? Even if you have only built one panel, you will know that the novelty of cutting and stripping wires, crimping and connecting very quickly wears off! After all, on a standard panel there are 88 wires to be stripped and 44 crimps! Why not get someone else to do all that and use the time saved for less boring pursuits (such as playing games!). Also, would it not be nice if this could be done for less extra cost than buying all the wire and crimps?
Plus, how about connecting a trackball and a spinner as well, all routed through one board and one cable to the PC, with everything simply a plug-in connection?
The Mini-PAC is a revolutionary combined Switch/Trackball/Spinner Interface with wiring harness. It is designed so that a complete control panel can be wired up in minutes. Ideal for OEM builders of controllers and cabinets but also suitable for the first-time builder

Harness Power!
The wiring harnesses are available for 32 switches (including joysticks and buttons) and with connection for Ultimarc trackballs and spinners. Along with each switch harness is a "daisy chain" ground harness. The total number of individual sections of wire on these harnesses is over 74, with over 144 terminations! Compare the cost of the wire and connectors, plus time saved, with the amazingly low prices of these premade harnesses!
The ground harness has 4 extra terminations, so that if necessary you can span longer distances between switches by "missing out" one connector. Switch connectors are female with option of 0.25 inch (6.3mm) or 4.7mm. These are designed for standard microswitch terminals.

minipac wiring harness

Switch Harness

Panel Sizes
Each switch wire on the harness is 13 inches long (330mm). The Mini-PAC board should be mounted near the center of the panel, giving a span between the furthest switches of 26 inches (660mm). The harnesses are designed to cover almost all standard size 2-player panels but extension kits are available for longer distances. Ground harness "hops" are 5 inches each.
If you are building a 4-player panel you can double up on Mini-PACs and harnesses.

Making your own?
You can make your own wiring harness if you prefer, because the Mini-PAC uses a standard 40-way 0.1 inch pitch pin header which can connect to a standard IDE disk drive cable, so you can use this inexpensive type of cable as the basis of your wiring.

Switch/Joystick Functionality
The Mini-PAC works identically to I-PAC2 board. All programming features identical, same number of inputs (32). Works in PS/2 or USB mode. For PS/2, you will need the optional PS/2 adaptor.

  • Tiny board! Only 2 1/4 X 1 1/2 inches!
  • Fully programmable key code set. Stored even after power off unlike some other interfaces which lose all data when powered off.
  • Dual interface. Full Speed USB or Keyboard - small adaptor plug available for PS/2 mode.
  • Lead plugs into keyboard socket on PC (with adaptor) or direct to USB port.
  • Can be programmed using special utilities (for DOS, Windows, Linux, MAC)
  • Using host software, an unlimited number of keycode configurations can be stored and downloaded on-the-fly. Retained on power off.
  • No separate power needed.
  • Does not use a matrix - no ghost keys.
  • Does not use a scanning method which causes a variable delay. Each input has it's own dedicated connection into the on-board CPU .
  • Fast running gives much better response than a standard keyboard controller. Key transmission and debounce uses a state method for each key. No delays between keys depressed at the same time. (essential for fighting games). No need for a keycode buffer.
  • 2 modes. Either uses standard MAME keys (default) or you can program your own character set.
  • Shift functions. Holding "Start1" and pressing other buttons sends a range of codes for MAME functions such as "escape", "Coin 1", "tab", "enter". This means no extra buttons are needed on the cabinet. In programmable mode any input can be the shift key and all keys can be programmed with a shifted code.
  • Connector for ordinary keyboard which can be used together with the controls if required. No switch-over delays mean you could even play a game using the control panel and keyboard at the same time. Advanced interrupt-driven code means the pass-through uses NO CPU cycles when the keyboard is idle.
  • Supports selective up/down key repeat in PS/2 mode (all keys repeat in USB mode) to give easy scrolling through lists with minimal CPU overhead and interface "clutter".
  • No special drivers needed. USB drivers are generic Windows.
  • Fully compatible with all Apple Macs which have USB ports.
  • Supports the Apple Mac "command" key and the Windows "GUI" keys.
  • Can be paired in any combination to increase the total number of inputs.
  • Keycode programming is integrated directly into many popular MAME front end for seamless launch of emulator or other applications which require different codesets.
  • Self-test LED indicator which shows and wiring or other problems.

Trackball/Spinner Functionality

In USB mode only. No extra PC connections are needed, all

communications go through one USB cable. Inputs for one 2-axis device

(trackball) and one single-axis device (spinner).

minipac trackball harness
Trackball/Spinner Harness

Important Legal Note.

For legal reasons we must state here that the Mini-PAC is not designed to be used in revenue-earning applications where a credit mechanism is used. The Mini-PAC contains no specific interface functionality for any credit device. Although it has inputs labelled "COIN", these are labelled as such because activating a switch connected to them causes the MAME "coin" keycodes (5 or 6) to be sent. These are designed to be used with panel pushbuttons not coin doors or note acceptors.

Recommended Wiring Procedure

Arrange the large switch connector on your left with the wires running towards the right, as shown in the right side of the diagram above, with the white polarising key at the bottom.
Working from the bottom of the connector, first connect the BLACK wire to the male connector on the ground harness.
Separate the rest of the wires into 4 groups. Start each group with the brown and red wires (bottom) and end with the purple and grey wires (top). You can ty-wrap the 4 groups close to the connector if you wish, or just lay the groups across the panel.
Now the wires from each group can be connected to the correct switches as shown on the diagram above. The table below may help, as this presents the connections in switch order and shows only the commonly-used switches
Then connect the ground harness to the other contact of each switch. Run along the controls in the most convenient path. You can miss out a connector if you need a longer routing as there are spares. Cut off the extra length.
If you are using the trackball/spinner harness connect the three other plugs to the trackball and spinner as shown and connect this to the board.
Ty-Wrap all wiring for neatness.

Reversing Trackball Axis
If you find one of the trackball axes moves "backwards", the resolution is to swap the X1 and X2 wires over (or Y1 and Y2). To do this, consult the diagram above and locate the correct pair of wires, at the main 30 way plug. The wire and contact can be removed from the black housing by carefully lifting the small tab on the side of the housing and pulling out. Swapping the pair of wires will reverse the direction of that axis.

Connecting Mouse Buttons
Mouse buttons can be connected to the trackball/spinner harness connector. These are not fitted as standard. They should be located as shown in the diagram above. You can swap over two spare wires from your switch harness. The wire and contact can be removed from the black housing by carefully lifting the small tab on the side of the housing and pulling out. Alternatively use two wires from the optional extension wire pack.
Keycodes, Programming and other Information.
All of the information on the I-PAC applies to the Mini-PAC. The default keycodes are the same, all programming information applies inclusing use of the WinIPAC utility, so check out the I-PAC pages for further information.

Troubleshooting Tips
All of the information on the I-PAC applies to the Mini-PAC. The LED indications are the same, all troubleshooting information applies, so check out the I-PAC pages for further information.

I-PAC Firmware version 50 Enhanced Modes

  • Traditional I-PAC keyboard mode unaffected. This is still the default.
  • Device mode can also be switched to Dual Directinput Game Controller or Dual Xinput Game Controller.
  • These modes appear as entirely different USB devices so there is no mixed-device confusion which causes issues in Retropie.
  • Selected mode is maintained after power off/on.
  • Standard Dinput and Xinput Game Controller modes are preset for ease of use without any configuration.
  • For advanced users who wish to create custom Game Controller configurations there are customisable game controller modes.
  • Modes can be switched by pressing Start1 (or user-set alternate I-PAC shift) and holding this, and Player 1 button 1 through 5, for 10 seconds.
  • Modes can also be switched by loading an appropriate config file using WinIPAC including “invisibly” via a command line.

These modes apply to Player 1 and 2 controls.

I-PAC Connection

Mode 2

Mode 3

Mode Switching
Hold Start1 and this
Button for 10 seconds with no other key activity:
Start1+P1SW1 > Mode 1
Start1+P1SW2 > Mode 2
Start1+P1SW3 > Mode 3
Start1+P1SW4 > Mode 4

Start1+P1SW5 > Mode 5


Dpad Left

Dpad Left


Dpad Right

Dpad Right


Dpad Up

Dpad Up


Dpad Down

Dpad Down

SW 1

Button 1


Mode 1 (Keyboard User Set)

SW 2

Button 2


Mode 2 (Dinput Preset)

SW 3

Button 3


Mode 3 (Xinput Preset)

SW 4

Button 4


Mode 4 (Dinput User Set)

SW 5

Button 5

Left Rear

Mode 5 (Xinput User Set)

SW 6

Button 6

Right Rear

SW 7

Z Left

Left Trig

SW 8

Z Right

Right Trig


Button 7



Button 8





Button 7






Customising the board

WinIPAC can only be used for customizing when in Mode 1 but changes made will also apply when switched to modes 4 and 5.

Chosen mode is maintained after power off/on.

Using WinIPAC, any input can be configured to any control including keys, power/volume, gamepad (Xinput or Dinput) across both players.
When this is done, keys configured as keyboard keys will respond in Mode 1, Keys configured as gamepad keys respond in modes 4 and 5.
Note this feature allows the entire 2-player panel to be configured as a one-player game controller if required, implementing every possible control.

Using WinIPAC, any key can be configured as mouse left or right button, Sleep, Wake, Vol Up, Vol Down. These will function in modes 1 and 4.

On Board LED

When powered on, the LED will stay lit once the board has passed self-test and detected by the host system.

When switching modes, the LED will flash off, the number of times according to the mode number selected, after the 10 second period.

Automatic Mode Switching

This is intended for use when WinIPAC is used for downloading configurations on the fly.

Mode will switch automatically under the following conditions:

  • If a keyboard-only configuration is downloaded and the board is currently in gamepad custom mode 4 it will switch to keyboard mode 1.
  • If a gamepad-only configuration is downloaded and the board is currently in keyboard mode 1, it will switch to gamepad custom mode 4.
  • If a gamepad-only configuration which includes an Xbox Home key is downloaded and the board is currently in keyboard mode 1, it will switch to gamepad custom mode 5.
  • If Winipac is started when the board is in Xinput mode it will switch automatically to keyboard mode. Note WinIPAC will self-close after switching.

Xinput Mode Notes

Owing to the limitations imposed by the Xinput protocol, the following are not supported in Xinput modes but are supported in keyboard and Directinput modes:

Mouse buttons

Volume up and down buttons

Power, sleep, wake buttons

LED control (I-PAC Ultimate I/O only)

WinIPAC for configuration

No trackball/spinner support

Additional Info

Note that a mode switch is essentially the same as unplugging a USB device and plugging in a different one, into the same port. It will take the host PC up to 30 seconds to notice this and initialize the new device.

The mode switching can be confirmed by observing the on-board LED or “Devices and Printers” , the USB connect sound or other indication on the host.

If mode switching fails to work, check that Start1 (or another connection) is configured as an I-PAC shift control. If this feature has been removed in WinIPAC, mode switching will not work. Any stuck/shorted controls will also inhibit mode switching.

“Backdoor” Reset

The board can be rest back into keyboard Mode 0 by pressing and holding the Start1 button on power up. This will work irrespective of the current board mode or input configuration. Note it must be a hard power-up or plug-in of the USB cable.