Open Pinball Project

The Open Pinball Project (OPP) was started in 2012 as a resource for pinball makers to have an inexpensive, fully open sourced project for controlling custom pinball machines. It is currently on a second generation design and has had a successful Kickstarter run of boards and components currently in the hands of makers all over the world.

Hardware

The OPP hardware is made up of three main components:

The Processor board is a Cypress Semiconductor CY8CKIT-049-42XX PSoC prototyping board that can be purchased from Mouser or Digikey.
The Interface board allows communications between Processor boards via a custom serial communications protocol.
The Wing boards allow the control of solenoids, lamps, LEDs or input from switches.

The following is an example of some fully assembled and wired OPP Processors with Wing boards.

Processor Boards

The Processor board can have up to four Wing boards controlling solenoids, incandescent lamps, or allowing input for switches. The Wing boards themselves can be combined in any configuration, so a single Processor board can support up to 16 solenoids, 32 switch inputs or 32 lamps. Each Wing board uses eight pins while the Interface board uses four.

All other pins are unused, except on the first board in the chain where the USB plug from the host controller is connected to the Interface board to provide power and serial connections for the other Processors in the chain.

The Processor itself does not run game rules or other game logic - a Controller like Mission Pinball running on a separate PC is still required to handle scoring and other game logic and to fire coils and light lamps as needed. The Processor simply provides the physical connection to playfield devices.

Serial Link

The 8-pin ribbon cable serial link between boards works in a similar fashion to a Token Ring network, where each Processor receives messages via the serial line, looks for commands addressed to its ID, removes that command from the message and then passes the remaining message to the next Processor in the chain. The Processor then performs the requested action such as firing a solenoid or turning on a lamp. Switch events are passed back to the primary board and up to the host controller.

The following image gives a visual idea of how messages flow between the Processors:

Like in the above image, each Processor assigns itself an ID on power-up based on its position in the serial chain, so boards do not need to be pre-programmed with IDs and can be placed anywhere in the chain, with the caveat that inserting a new card in the middle of a chain will change the ID of every board after it, which will change the hard-coded numbering in controllers like MPF.

Solenoid Wing

The Solenoid wing uses FQP13N06L MOSFETs to control up to four individual coils via a ground sink method, where the coils themselves are wired to the positive side of the high voltage power supply and the MOSFET provides a ground path when activated, firing the coil.

Standard coil voltages are 24V to 48V and upwards of 10A of current.

There are two connectors on the Solenoid wing - the larger 6-pin has four pins for the coil connections and two for ground. The 4-pin connector is for direct control switch inputs, for devices like slingshots or pop bumpers that require fast response to switch hits in order to fire coils.

Note that the OPP boards support direct control switch programming, so that such devices can be configured in the firmware itself, and the 4-pin connector can cause some packaging issues, so it is recommended to leave the 4-pin connector out when building the boards unless you need it specifically.

However, using the direct switches allows the game to be tested without a host controller, since pop bumpers, slingshots and flippers will work without it.

Incandescent Wing

The Incandescent wing uses 2N7000 MOSFETs to control up to eight direct wired incandescent lamps via the same ground sink method as the coils.

Lamps require a high current 12V power supply as each 6.3V bulb needs about a 1/4A to fully light.

Direct wired means that each lamp is wired up and controlled individually via the 8-pin connector, rather than in the Matrix style that most commercial pinball machines used until recently.

The other 2-pin connector is for the Ground connection.

Switch Wing

Switches are wired directly to the Processor board via an 8-pin 2.54mm locking header.

Unlike the Solenoid and Incandescent wings, the Switch wing is set up as High-side, where the switch pins are at 5V and playfield and cabinet switches are tied to Ground, so that when a switch is activated, the pins are grounded and the switch is considered 'closed'. It is set up this way since the Processor pins have a Pull-Up resistor on them that is tied to 5V.

So instead of providing a ground path, switches are proving a positive voltage path.

Interface Wing

The Interface wing has no transistors or other electronic parts on it other than connectors. Its purpose is to distribute low voltage power (primarily 5V) and serial connections between each Processor board.

Before You Start

Determine Your Board Layout

Prior to sourcing and purchasing the OPP boards and components, you need to know how many solenoids, lamps and switches you need to support, and a general layout of where you will put boards and how they will be mounted.

For example, a custom game might require 31 inputs, 10 solenoids (with 10 direct inputs), and 43 incandescent bulbs. This could be accomplished with four Processor boards with four Interface wings, three Solenoid wings, six Incandescent wings and five Switch wings. Technically this is more than strictly required as the Processor boards could handle a denser configuration, but it cuts down on the total wiring required, saving significant time and money.

Alternatively, if you're converting a Williams Jokerz machine, It has 19 solenoids (includes direct inputs), 39 inputs and 63 incandescent bulbs (which includes 9 flashers). A possible layout for that is five Processor boards with five Interface wings, four Solenoid wings, eight Incandescent wings and five Switch wings.

Once the total number of Processor and Wing boards has been determined, parts can be ordered.

Power Supply Needs

When running solenoids and lamps, you'll need three voltages: 5V 3A for logic, 12V 10A for lamps and 24V to 48V 10A for solenoids. See the Power Supply section for details of what is available.

Getting Blank Boards

The OPP site itself does not sell blank boards and there currently is no one selling fully populated and tested boards. However, given the open source nature of the project, there are multiple ways to get the blanks.

The easiest is to order boards from MezelMods as they offer blanks for a very reasonable $1US per board.

The next option is to create Gerber files from the KiCad files located in the OPP SVN repository. For this you'll need to download KiCad, which is a printed circuit board design tool that was used to create the OPP boards. Once you have the Gerber files, they can be uploaded to a number of low-cost PCB manufacturers such as:

Each PCB maker has plusses and minuses that are too involved to go into in this wiki, but SeeedStudio has good prices and fast shipping.

Getting PCBs made can be a fairly advanced process, so it is recommended to simply purchase the already-made boards via MezelMods. They also offer additional parts that are less expensive than purchasing through Digikey or Mouser such as the FC-8P connectors and the 1x40 2.54 mm headers.

Getting Components

Once you have the bare boards, they will need to be fully populated with components, which are not included - they will need to be sourced separately. The following is a Bill of Materials for each Processor and Wing board.

Processor Board

Quantity	Mouser Part #	Description	Price Est.
1	727-CY8CKIT-049-42XX	Cypress Semiconductor PSoC 4200 Prototyping Kit	$3.98/ea
1	649-68602-108HLF	2 x 4 position 2.54 mm Header	$0.45/ea
2	571-9-146278-0	40-pin 2.54 mm Header	$2.51/ea
2	SX1100-B	2.54 mm Jumper	$0.10/ea

Note: The 40-pin header is available much cheaper in larger quantities from eBay - search for "1x40 2.54mm header".