SternFA

Stern / Bally MPU, based on FPGA

Hardware version 2.0

Software version 5.30

user manual

v1.3 23.10.2026

German version: SternFA_Bedienungsanleitung.html. French version: SternFA_manuel_utilisateur.html. The chapter numbering is the same in all three.

This manual describes hardware version 2.0 (PCB v2.00 to v2.02) with software 5.30. For the older boards (HW 1.0 and HW 1.1) there is a manual of its own, SternFA_HW1_x_user_manual.html (software x.30, it replaces the manual v1.04). What changed between the two board generations is listed in chapter 12.

Important remark
1. Introduction
2. Quickstart
3. Installation
- 3.1. What SternFA replaces and what it does not
- 3.2. What is on the board
4. DIP switch settings
5. Boot sequence
6. Buttons and LEDs on the board
- 6.1. The three status LEDs
- 6.2. The buttons
7. The SD card
8. Credits and high scores
9. The FA-Control interface (ESP32-C3)
10. Programming the FPGA
11. Board variants
12. What is new in hardware 2.0
13. Not implemented yet, and known limitations
Appendix A 'game select'
Appendix B Quick reference

Important remark

By using SternFA it is possible to damage your pinball machine. As this is a private project with NO commercial interest the author accepts no liability for any damage that may arise by using SternFA!

1. Introduction

SternFA uses a (low cost) FPGA which emulates the hardware of a Stern MPU. It rebuilds the MC6800 processor, the two PIA 6821, the 6810 scratchpad ram, the 5101 CMOS ram and the four game roms, and it drives the original display, lamp, switch and solenoid connectors of the machine.

Because the same MPU family sits in Bally machines, SternFA runs Stern MPU-100, Stern MPU-200 and Bally -17/-35 games - 238 game numbers are on the SD card image, see Appendix A. Which one runs is set with the eight switches of DIP bank S1.

SternFA is a 100% hobby project. This makes the solution cheap; depending on where you buy your components it is possible to build your Stern replacement MPU for less than 80.

What do you need?

Basic soldering skills (SMD components can be ordered pre-assembled in most shops)
The possibility to read/write micro SD cards
A PC with a USB port and a USB Blaster in order to be able to program the FPGA

Three things are worth knowing before you begin:

All DIP switches are read once, during boot. Changing one while the game runs has no effect at all - and on hardware 2.0 that is not a convention but a physical fact, see chapter 4.3.
The board needs its SD card - unless the game rom sits on the ESP32 module (chapter 9.7) or in the configuration flash (from 5.30, chapter 5.3). The game roms are loaded anew at every power-up: from the module if it has the selected game, otherwise from the card, and without a card from the flash. If the game is in none of the three places, there is no game.
The version shown at boot starts with a 5 on this board. That digit identifies the board variant - see chapter 11. If it does not say 5, you have the wrong program in the FPGA.

2. Quickstart

Download the latest SD card image and the FPGA program for hardware 2.0 from lisy.dev (chapter 10)
Write the image to a micro SD card and put the card into the board
Program the FPGA - take the 5.xx version
Configure DIP bank S1 'game select' according to your pinball (Appendix A)
Leave DIP bank S2 'options' all OFF for a start
Replace your original Stern/Bally MPU with SternFA
Switch the game ON
Watch the info display for the first few seconds and check that version and game number are what you expect (chapter 5.2)
Enjoy

3. Installation

SternFA boards have the same connectors and the same mounting holes as the original Bally/Stern MPUs, so replacing the board can be done in seconds. Switch the machine off, pull the original MPU, put SternFA in, done.

3.1. What SternFA replaces and what it does not

Replaced: the MPU board - processor, ram, roms, both PIAs and the glue logic around them.

Still needed: everything outside the MPU. SternFA drives the original connectors and expects the original boards behind them:

the lamp driver board (AS-2518-23 or equivalent) with its address decoders,
the solenoid driver board,
the display board(s),
the rectifier / power supply, which also delivers the zero cross signal,
for MPU-200 games, the Stern SB-300 sound board on connector J5.

SternFA does not rebuild any of these. It behaves towards them exactly as the original MPU did.

3.2. What is on the board

FPGA	Cyclone IV E, EP4CE6E22C8, on a `dev_open` development board that plugs onto the SternFA PCB
Clock	50 MHz oscillator on the FPGA board; the emulated 6800 runs at about 446 kHz for Bally / MPU-100 games and about 893 kHz for Stern MPU-200 games - the clock of the original 3.58 MHz crystal divided by 8 and by 4
SD card	micro SD holder, read in raw mode - the game roms come from here
FRAM	FM25CL64B, keeps the CMOS ram content over a power cycle (chapter 8)
ESP32-C3	socket X7 for an ESP32-C3 Super Mini, optional, for the FA-Control test interface (chapter 9)
DIP switches	S1 game select (8), S2 options (6), S9 ESP32 options (4, read by the ESP32, not by the FPGA)
Buttons	SW2 reset and SW3 on the FPGA board, S6 'Bally Test', S33 bookkeeping reset, S8 ESP32 test
LEDs	red 'SD card error', yellow 'zero cross', green 'Bally' - in parallel with the LEDs of the FPGA board

4. DIP switch settings

4.1. DIP switch S1: game select

Here you select which game SternFA should run. This depends on the roms placed on the SD card; Appendix A lists what the current image contains.

The switch pattern is simply the game number in binary, S1 being the lowest bit:

Switch	S1	S2	S3	S4	S5	S6	S7	S8
adds	1	2	4	8	16	32	64	128

ON = the value is added. Game 101 (MATAHARI) is therefore 1 + 4 + 32 + 64 = S1, S3, S6 and S7 ON, everything else OFF. Appendix A spells this out for every game.

Game numbers 0 to 63 are Stern MPU-200 games and run with the higher processor clock. From 64 upwards SternFA runs the Bally / MPU-100 clock. This is derived from the game number alone (switches S7 and S8), which is why option DIP 3 exists - see 4.2.3.

4.2. DIP switch S2: options

Default setting is all OFF.

4.2.1. S2-Dip1 -> zero cross emulator

A Bally/Stern MPU needs a 'zero cross' signal in order to work properly; this signal comes from the 12 volt power supply. The existence of the signal is checked during boot.

With Dip1 ON SternFA generates the signal itself (100 Hz, that is a 50 Hz mains), so for testing on the bench you only need a 5 volt supply. Note that the timing is different with emulated zero cross - use it on the bench, not in the machine.

4.2.2. S2-Dip2 -> save nvram content to FRAM

SternFA uses a FRAM chip to save the nvram content (high scores and extended settings). For bench testing Dip2 can be set momentarily to ON, which makes SternFA save the current nvram content continuously.

During normal gameplay the nvram content is saved automatically anyway - triggered by the test switch, the game over relay and the credit button.

4.2.3. S2-Dip3 -> force Bally game

With SternFA you can also run all games that run on BallyFA, by using the BallyFA rom SD image. Set this option to ON in that case - otherwise all games with a number below 64 would run with the higher MPU-200 processor clock.

The Stern SD image provided includes both Stern and Bally games with the correct numbering, so with that image you do not need this option.

Dip4 and Dip5 swapped places in software 5.06. Anti flicker used to be Dip4 and is Dip5 now; Dip4 is the FA-Control permission, the same switch as on AtariFA. If you move over from an older version with anti flicker in use, move that switch from 4 to 5.

4.2.4. S2-Dip4 -> allow FA-Control to take over

New in hardware 2.0. On the older boards this switch has no function.

ON allows an ESP32-C3 module plugged into socket X7 to take control of the machine for testing - see chapter 9. With the switch OFF the module can only read; it can never drive lamps, coils or displays.

If you have no ESP32 module in the socket, leave this OFF. It changes nothing either way, but OFF is the setting that cannot surprise you.

4.2.5. S2-Dip5 -> anti flicker for games with LEDs

With Dip5 ON SternFA changes the timing of the zero cross signal. Bally games are known for flickering LED replacement lamps; usually each LED needs a resistor in parallel to solve this. With this option the LEDs are flicker free without the additional resistors.

4.2.6. S2-Dip6 -> init nvram

With Dip6 ON SternFA initialises the nvram of the selected game to zero during boot. This is useful if you want to reset all ram content, for example after loading a different game into the same slot.

Set it back to OFF and power cycle afterwards - otherwise the machine will wipe its settings on every start.

4.3. All 14 DIP switches are read once, at boot

Both banks - the eight of S1 and the six of S2 - are read once, in the first moments after power-up, and the values are then held until the next reset. Turning a switch while the machine is running does nothing.

On hardware 2.0 there is a hard reason for this. The two DIP banks and the ESP32-C3 share the same two signal lines into the FPGA, through two multiplexers (U1 and U2). During boot the multiplexers are switched to the DIP banks; as soon as the switches have been read they flip over to the ESP32 and stay there. After boot the FPGA is physically no longer connected to the DIP switches.

The practical consequence: after changing any switch, power off and power on, or press the reset button SW2 on the FPGA board.

This also means the FA-Control permission of 4.2.4 cannot be revoked while a takeover is running - see chapter 9.3.

5. Boot sequence

5.1. Phase 0: reading the DIP switches

Immediately after power-up - or after pressing SW2 - SternFA reads both DIP banks. This takes microseconds and you will not see it. Solenoids and displays are held off during this window.

5.2. Phase 1: the info display

Then the FPGA writes the info display to the displays of your machine, before any game code runs. It stays up for the first few blinks of the green LED:

Display	Shows
Player 1	version of the FPGA program running, e.g. `5 0 6`. The first digit is the board variant (chapter 11)
Player 2	the selected game number from S1, right aligned. A leading `2` on the far left means a Stern MPU-200 game was selected
Player 3	`050963` - the lisy.dev identifier for FPGA based MPUs. It is fixed and only tells you that the display path works
Player 4	the value of the option bank S2 as a number, 0 to 63: Dip1 = 1, Dip2 = 2, Dip3 = 4, Dip4 = 8, Dip5 = 16, Dip6 = 32
Credit / status	a counter, counting down 4, 3, 2, 1, 0 with each blink of the green LED

Check player 1 and player 2 at every first start. They tell you whether the right program is in the FPGA and whether the game select switches are set to what you meant.

5.3. Phase 2: SD card read

Hardware 2.0 only: first SternFA asks the ESP32 module whether it holds a rom for the selected game (chapter 9.7). If it does, the SD card is not read at all and the status display shows 3. Without a module, without a rom there or without an answer, the boot continues as described below; with no module plugged in it takes up to 3 seconds longer.

SternFA reads the rom of the selected game from the SD card. If this fails, the red LED 'SD card error' first blinks a code and then stays lit, and an error digit appears in the status display:

Digit	Meaning
`1`	general problem with the SD card - no data could be read. Card missing, not written raw, or not readable
`2`	CRC error: data was read, but the checksum of the game block does not match. The image is damaged, or the card is unreliable
`3`	no error: the rom came from the ESP32 module (hardware 2.0 only, chapter 9.7)
`4`	no error: no SD card, the rom came from the configuration flash (x.30 and later)
`8`	no SD card, and the selected game is not in the configuration flash (x.30 and later)

If the read succeeds, the red LED stays dark and no error digit appears.

From x.30 on: games without an SD card. When no SD card answers, SternFA loads the game from the configuration flash (EPCS16) of the FPGA board, under the same game number as on the card. The regular release file SternFA_<version>.jic carries no games, for copyright reasons; without a card the boot then ends with digit 8, and the red LED blinks eight times quickly, then pauses. The games get into the flash with a locally built SternFA_<version>_roms.jic (bitstream plus every game of SD card v098). A card with a CRC error (digit 2) is not replaced by the flash, it stays an error.

On hardware 2.0 the order is therefore ESP32 module → SD card → flash. Software 5.30 needs the pin assignment of PCB v2.02 for this. A v2.00 or v2.01 can be modified with two cuts and one wire (chapter 13); left unmodified it loses the connection to the ESP32 module with 5.30 and therefore stays on 5.06.

5.4. Phase 3: program execution

The nvram content of the selected game is fetched from the FRAM into the CMOS ram, and the game code from the SD card starts running. This is the normal Bally/Stern boot sequence: the green 'Bally' LED blinks a few times, and when the code is up and the interrupts run regularly the green LED goes and stays ON.

From here on, the machine behaves like the original.

6. Buttons and LEDs on the board

6.1. The three status LEDs

The LEDs on the SternFA PCB are wired in parallel with the LEDs on the FPGA board, so you can read them on either one.

LED	Meaning
red - SD card error	dark is the normal state. Blinking then steady = the SD card could not be read, see 5.3
yellow - zero cross	lit is the normal state. It goes dark when the zero cross signal from the power supply is missing (two or more edges lost in a row). Dark yellow LED and a machine that does nothing = look at the rectifier board, not at SternFA
green - Bally	blinks during the boot sequence of the game code, then stays lit while the game runs. Steady dark or a blink that never stops means the game code is not getting through its start-up

While FA-Control has taken over the machine (chapter 9), the green LED is lit continuously - the CPU is stopped then, so it cannot mean anything else.

6.2. The buttons

Button	Where	Function
SW2	on the FPGA board	reset. Restarts the whole boot sequence including the DIP read. Use it after changing a switch
S6 'Bally Test'	on the SternFA PCB	wired in parallel to the self test switch in the coin door. Puts the game into its self test, so you can run switch, lamp, solenoid and display tests on the bench without a coin door
S33	on the SternFA PCB	the S33 bookkeeping reset of the original MPU (it triggers the NMI). Same function as on the original board
S8 'Test'	next to socket X7	belongs to the ESP32-C3, not to the FPGA. See 9.6
SW3	on the FPGA board	no function so far. It is wired to the FPGA but not used - see chapter 13

7. The SD card

The game roms live on the SD card, and SternFA reads them at every power-up. The card is read raw - there is no file system on it. Write the downloaded image to the card with a raw imaging tool (for example Win32DiskImager, balenaEtcher or dd); simply copying a file onto a formatted card will not work.

Each game occupies a block of 64 KB on the card, and the blocks are laid out in the order of the game numbers of Appendix A. The FPGA calculates the position from the S1 switches alone, which is why the game number and the image version have to match - the game numbers in Appendix A are those of image v0.98.

The image also contains a checksum per game block. That is what error code 2 in 5.3 refers to; it catches a damaged download or a failing card before the game starts behaving strangely.

Any ordinary micro SD card works. Size does not matter - the image is small - but a card that has been in service for years is exactly the kind of part that starts producing error 2.

8. Credits and high scores

The original MPU keeps its CMOS ram alive with batteries, which is what eventually destroys so many of these boards. SternFA has no battery. Instead it copies the nvram content into the FRAM chip on the board and reads it back at the next start.

You do not have to do anything for this. Saving is triggered automatically by the test switch, the game over relay and the credit button - the same events at which the original board would have settled down. Option Dip2 (4.2.2) forces continuous saving for bench testing, and option Dip6 (4.2.6) wipes the content.

FRAM needs no battery, has no write cycle limit worth thinking about, and does not leak.

9. The FA-Control interface (ESP32-C3)

New in hardware 2.0. The board has a socket - X7 - prepared for an ESP32-C3 Super Mini. It runs FA-Control, a small firmware that opens a WLAN and serves a test interface in your browser: switch every lamp individually, pulse every coil, watch all switches live, write digits to the displays.

This is a tool for the bench and for fault finding, not an accessory for normal play. If you plug nothing into X7, you will never notice this interface - the board behaves exactly as it does without.

This feature has been tried on the bench, but not yet in a real machine. It is new in software 5.04; with 5.06 connecting, the board report, handing control back and the watchdog worked on the bench. Treat the first takeover in a machine as an experiment, with the machine you can afford to switch off. Chapter 13 lists what to look at first.

9.1. The permission: option DIP 4

A test tool must not be able to interfere with a running game unasked. So two things have to come together:

The ESP32 module actively asks ("I would like to take over").
Option DIP 4 is ON.

With option 4 OFF, the web interface refuses to take over with the message "DIP 4", and the game carries on undisturbed. Reading is still allowed: you can follow switch states during a running game without giving anything up.

Up to the first 5.06 build the permission was on option DIP 5, and the message named the wrong switch. Since 5.06 it is DIP 4, as on AtariFA, and the message is right.

9.2. What happens while it has control

The game is stopped. The processor is held in reset, and lamps, coils and displays now come from the web interface. It has to work that way: if the game kept running it would overwrite every lamp you set by hand within a few milliseconds.

The green 'Bally' LED is lit continuously while this lasts.

The game then starts over. It cannot be paused and resumed. A game in progress is lost, so only take control in attract mode or on the bench.

9.3. How control is handed back

In the web interface, press "hand back control".
Do nothing. If the module goes quiet for two seconds, SternFA hands back by itself. That is the safety net for a module that locks up, reboots or loses contact - the machine does not stay stuck in the handover, it comes back as an ordinary pinball.
Switch the machine off and on, or press SW2.

The option DIP is not an emergency stop on SternFA. Unlike AtariFA, where option 4 is read continuously, DIP 4 here is the value latched at boot - after boot the DIP lines are physically switched over to the ESP32 (chapter 4.3). Setting DIP 4 to OFF during a takeover does nothing until the next reset. Pulling the module, using the web interface, or resetting are the ways out.

9.4. What the web interface learns from the board

On connecting, FA-Control asks the board what it is made of and configures itself - nothing has to be typed in. SternFA answers:

Identification	`SternFA`
Software version	the same one the info display shows, e.g. `5.0.6`
Lamps	60
Solenoids	19
Switches	40
Sounds	0 - see below
Displays	5, six digits each (status/credit plus four players)

The numbering follows the Bally/Stern hardware and is the same one LISY uses:

Lamps 0 to 59 of the main lamp board (AS-2518-23). The number is address + 15 x data line, that is: lamps 0-14 are the first group, 15-29 the second, 30-44 the third and 45-59 the fourth.
Solenoids 1 to 19. 1 to 15 are the momentary solenoids, exactly the numbers the game's own self test uses. 16 to 19 are the four continuous outputs, among them the coin lockout and the flipper enable.
Switches 0 to 39, strobe x 8 + return. Strobe 1 return 1 is switch 0.

Sound is reported as 0 and the sound buttons stay empty. The Stern SB-300 sound board hangs on the processor bus, and during a takeover the processor is stopped - driving it would mean faking bus cycles. That is not implemented; sound commands are accepted and do nothing.

9.5. Connecting it

The ESP32 module simply plugs into X7; there is nothing to solder. The board powers it - no USB cable is needed in normal operation. You only plug one in to load the FA-Control firmware or to read the boot log. For the initial WLAN setup FA-Control opens its own access point on first start; see the FA-Control documentation for that.

Three signals run between the module and the FPGA: the two serial lines and one line with which the module asks for control. All three are already on the PCB, nothing has to be wired.

9.6. The ESP32 button S8 and DIP bank S9

These two belong to the ESP32 module, not to the FPGA. The FPGA neither sees nor cares about them, and they have no effect if the socket is empty.

S8 'Test'	push button on GPIO9 of the module. What it does is defined by the FA-Control firmware
S9, 4 switches	DIP1 = module on/off (OFF puts the ESP into deep sleep), DIP2 = switch the blinking status LED off, DIP3 and DIP4 = free

The exact meaning can change with the FA-Control firmware version - the FA-Control documentation is the reference, not this manual.

9.7. Game rom from FA-Control instead of the SD card

From software 5.0.6 on the ESP32 module can hold game roms, and SternFA then boots without an SD card. They are managed in menu 08 GAME ROMS of the web interface (FA-Control 1.21 or newer):

Upload: device SternFA, the game number (the one set on the game select DIPs and shown on the boot display) and the game image that also goes onto the SD card: exactly 65,536 bytes per game, with its checksum at the end. An image with a wrong checksum is rejected.
Load from lisy.dev: the images are in swrep/misc/FA_Control/roms/SternFA/, named nnn.bin or nnn_Title.bin, nnn being the three-digit game number, e.g. 012_Stars.bin. On the module the game is then kept as SternFA/012.

At power on:

SternFA reads the DIP switches (phase 1).
Right after that it asks the module for the selected game, repeating the question for up to 3 seconds.
If the rom is there, it is transferred (less than a second) and checked. The status display shows 3, the SD card is not touched.
If it is not there, the module says "no" at once and SternFA reads the SD card as usual. The same happens if no answer comes or the transfer was faulty.

Keep in mind:

The module has to be awake at power on (S9-DIP1 ON). In deep sleep it does not answer, and SternFA takes the SD card after 3 seconds.
Option DIP 4 plays no part here. It only permits the takeover (9.1); loading the game through the module works without it.
The nvram stays in the board's FRAM, exactly as with an SD card boot. Credits and high scores belong to the game number, not to where the rom came from.
The module needs a storage area of its own for this, which only a full installation of FA-Control over USB sets up. Without it there is no tile 08 and the module says "no" at once. About 60 games fit.
Which request came last and what the module answered is shown at the top of menu 08 under LAST BOOT REQUEST - a missing rom can be fetched from lisy.dev right there.
Since 5.0.6 the web interface learns the full game number. Before, SternFA reported the units digit only, so naming files for games 5, 15 and 105 fell together. Now they are named like the roms: SternFA/012.cfg.

10. Programming the FPGA

Everything you need to get the software onto the board is described on my website, and it is kept up to date there:

https://lisy.dev/documentation-01.html

You will find there which programmer software you need, how to install the driver for the USB Blaster, and how to program the FPGA.

The FPGA program itself and the SD card image are in the SternFA software repository:

https://lisy.dev/swrep/SternFA

Make sure you take the version for your board - see chapter 11. For hardware 2.0 that is the file whose name starts with SternFA_5, for example SternFA_530.jic. A PCB v2.00/v2.01 that has not been modified as described in chapter 13 stays on SternFA_506.jic.

The FPGA on this board is configured from a serial configuration device, so the program stays in place after a power cycle. You program it once, not at every start.

11. Board variants

The same design runs on several boards, and the FPGA program is not interchangeable between them - the pin assignment differs, and a wrong program will at best show nothing and at worst drive the wrong pins.

Version starts with	Board
1	SternFA PCB v1.0 with the Cyclone IV v4 FPGA board - see the hardware 1.x manual
3	SternFA PCB v1.1 with the Cyclone IV v4 FPGA board - see the hardware 1.x manual
4	SternFA PCB v1.1 with the Cyclone 10 FPGA board - see the hardware 1.x manual
5	SternFA PCB v2.0 with the `dev_open` Cyclone IV board - this manual

Within the 5 series: from 5.30 on, only PCB v2.02 or a modified v2.00/v2.01 (chapter 13).

The info display tells you which program is running: the first of the three version digits on player display 1 is the board number. If you loaded the wrong one, the displays will most likely stay dark or show nonsense - check that digit first.

12. What is new in hardware 2.0

If you know the older boards, this is the short list:

A different FPGA board. Hardware 2.0 uses the dev_open Cyclone IV board. The FPGA chip is the same EP4CE6E22 as on the v1.1 Cyclone IV board, but the pin assignment is completely different - hence the new version series 5.xx.
Reset and the second button moved onto the FPGA board. What used to be S8 and S9 on the SternFA PCB is now SW2 and SW3 on the FPGA board.
A socket for an ESP32-C3 (X7) with its own test button S8 and a 4 way DIP bank S9, plus the two multiplexers U1 and U2 that hand the two DIP return lines over to the module after boot. This is what makes chapter 9 possible - and what makes chapter 4.3 a physical fact rather than a convention.
Option DIP 4 is the FA-Control permission, and anti flicker moved to DIP 5 (from 5.06, on all boards). Up to 5.05 it was the other way round.
Game roms can come from the ESP32 (from 5.0.6, chapter 9.7), so the SD card is no longer required.
Two pull-up resistors on the DIP return lines are missing on PCB v2.00 and have to be added by hand (chapter 13). From v2.01 on they are fitted.
From PCB v2.02 on, ESP32_RX and SB_IRQ/ have swapped their FPGA pins. Software 5.30 needs this for the games from the configuration flash. A v2.00/v2.01 can be modified (chapter 13).
The unused SB_IRQ input is still routed on the board but is not evaluated, as before.

Everything that mattered to the player is unchanged: same connectors, same mounting holes, same game list, same SD card image, same options 1 to 3 and 6 - option 4 (anti flicker) now sits on DIP 5.

13. Not implemented yet, and known limitations

PCB v2.00 needs two extra pull-up resistors. The return lines of the two DIP banks (GS_Dips and Opt_Dips) have no pull-up on this board: on v1.x the FPGA's internal pull-up did the job, but on v2.0 the multiplexers U1/U2 sit between the DIP banks and the FPGA, and the internal pull-up ends up on the wrong side. Without the two resistors the board reads no DIP switch at all - the info display shows game 255 and the boot stops with an SD card error. Fit a 10 kOhm resistor from each of the two lines to +3V (3.3 V). From PCB v2.01 on they are part of the assembly.
PCB v2.00 and v2.01 need a modification for software 5.30. From 5.30 on the FPGA uses four pins of the configuration flash after boot, to load games from it (5.3). Right next to the flash clock pin there must then be no output - and that is exactly where, on FPGA PIN_11, the transmit line to the ESP32 module used to be. From PCB v2.02 on it therefore swaps places with the unused SB_IRQ/ line. On a v2.00/v2.01:
1. cut the connection FPGA PIN_11 ↔︎ ESP32_RX
2. cut the connection FPGA PIN_119 ↔︎ SB_IRQ/
3. add a wire from FPGA PIN_119 to ESP32_RX (socket X7, GPIO6 of the module)
4. optionally add a wire from SB_IRQ/ to FPGA PIN_11 (the software does not read it so far)
The modification has been tried on a v2.00. If you do not want to modify your board, stay on SternFA_506.jic.
FA-Control has run on the bench, not yet in a machine. Software 5.04 was the first version with it; with 5.06 the web interface connects and shows SternFA / 5.0.6 with 60 lamps, 19 coils, 40 switches, 5 displays, handing control back restarts the game and pulling the module falls back through the watchdog. Still open, in this order: do the displays show what you type - does a single lamp light the lamp you asked for - does a coil pulse the right coil. If a lamp or a coil is off by a group, that is a mapping detail and it is fixable in one place; report what you saw.
Sound cannot be driven by FA-Control - see 9.4.
Loading the game rom from the ESP32 has been tried on the bench, not yet in a machine (new in 5.0.6). If the status display shows no digit instead of 3, the SD card was read after all; menu 08 then shows what the module answered last.
The option DIP is not an emergency stop during a takeover - see 9.3.
SW3 on the FPGA board does nothing. It is wired to the FPGA and reserved; no software version has used it so far. The self test is on S6 'Bally Test' and in the coin door.
Option DIP 4 and 5 changed meaning. Up to 5.05 (and in all older manuals) DIP 4 was anti flicker and DIP 5 unused or the FA-Control permission. Since 5.06 DIP 4 is the FA-Control permission and DIP 5 anti flicker. If you move a board from an older manual's settings, check both switches.

Appendix A 'game select'

Game numbers of SD card image v0.98. ON = switch closed. The pattern is the game number in binary with S1 as the lowest bit, see 4.1.

No	S1	S2	S3	S4	S5	S6	S7	S8	Game	Remark
0	off	off	off	off	off	off	off	off	Meteor	Stern MPU-200
1	on	off	off	off	off	off	off	off	Galaxy	Stern MPU-200
2	off	on	off	off	off	off	off	off	Ali	Stern MPU-200
3	on	on	off	off	off	off	off	off	Big Game	Stern MPU-200
4	off	off	on	off	off	off	off	off	Seawitch	Stern MPU-200
5	on	off	on	off	off	off	off	off	Cheetah	Stern MPU-200
6	off	on	on	off	off	off	off	off	Quicksilver	Stern MPU-200
7	on	on	on	off	off	off	off	off	Stargazer	Stern MPU-200
8	off	off	off	on	off	off	off	off	Nine Ball	Stern MPU-200
9	on	off	off	on	off	off	off	off	Iron Maiden	Stern MPU-200
10	off	on	off	on	off	off	off	off	Viper	Stern MPU-200
11	on	on	off	on	off	off	off	off	Dragonfist	Stern MPU-200
12	off	off	on	on	off	off	off	off	Cue	Stern MPU-200
13	on	off	on	on	off	off	off	off	Flight 2000	Stern MPU-200
14	off	on	on	on	off	off	off	off	Freefall	Stern MPU-200
15	on	on	on	on	off	off	off	off	Lightning	Stern MPU-200
16	off	off	off	off	on	off	off	off	Split Second	Stern MPU-200
17	on	off	off	off	on	off	off	off	Catacomb	Stern MPU-200
18	off	on	off	off	on	off	off	off	Orbitor 1	Stern MPU-200
19	on	on	off	off	on	off	off	off	Meteor	Stern MPU-200 Freeplay
20	off	off	on	off	on	off	off	off	Galaxy	Stern MPU-200 Freeplay
21	on	off	on	off	on	off	off	off	Ali	Stern MPU-200 Freeplay
22	off	on	on	off	on	off	off	off	Big Game	Stern MPU-200 Freeplay
23	on	on	on	off	on	off	off	off	Seawitch	Stern MPU-200 Freeplay
24	off	off	off	on	on	off	off	off	Cheetah	Stern MPU-200 Freeplay
25	on	off	off	on	on	off	off	off	Quicksilver	Stern MPU-200 Freeplay
26	off	on	off	on	on	off	off	off	Stargazer	Stern MPU-200 Freeplay
27	on	on	off	on	on	off	off	off	Nine Ball	Stern MPU-200 Freeplay
28	off	off	on	on	on	off	off	off	Iron Maiden	Stern MPU-200 Freeplay
29	on	off	on	on	on	off	off	off	Viper	Stern MPU-200 Freeplay
30	off	on	on	on	on	off	off	off	Dragonfist	Stern MPU-200 Freeplay
31	on	on	on	on	on	off	off	off	Cue	Stern MPU-200 Freeplay
32	off	off	off	off	off	on	off	off	Flight 2000	Stern MPU-200 Freeplay
33	on	off	off	off	off	on	off	off	Freefall	Stern MPU-200 Freeplay
34	off	on	off	off	off	on	off	off	Lightning	Stern MPU-200 Freeplay
35	on	on	off	off	off	on	off	off	Split Second	Stern MPU-200 Freeplay
36	off	off	on	off	off	on	off	off	Catacomb	Stern MPU-200 Freeplay
37	on	off	on	off	off	on	off	off	Orbitor 1	Stern MPU-200 Freeplay
38	off	on	on	off	off	on	off	off	NOT USED	–
39	on	on	on	off	off	on	off	off	NOT USED	–
40	off	off	off	on	off	on	off	off	NOT USED	–
41	on	off	off	on	off	on	off	off	NOT USED	–
42	off	on	off	on	off	on	off	off	NOT USED	–
43	on	on	off	on	off	on	off	off	NOT USED	–
44	off	off	on	on	off	on	off	off	NOT USED	–
45	on	off	on	on	off	on	off	off	NOT USED	–
46	off	on	on	on	off	on	off	off	NOT USED	–
47	on	on	on	on	off	on	off	off	NOT USED	–
48	off	off	off	off	on	on	off	off	NOT USED	–
49	on	off	off	off	on	on	off	off	NOT USED	–
50	off	on	off	off	on	on	off	off	NOT USED	–
51	on	on	off	off	on	on	off	off	NOT USED	–
52	off	off	on	off	on	on	off	off	NOT USED	–
53	on	off	on	off	on	on	off	off	NOT USED	–
54	off	on	on	off	on	on	off	off	NOT USED	–
55	on	on	on	off	on	on	off	off	NOT USED	–
56	off	off	off	on	on	on	off	off	NOT USED	–
57	on	off	off	on	on	on	off	off	NOT USED	–
58	off	on	off	on	on	on	off	off	NOT USED	–
59	on	on	off	on	on	on	off	off	NOT USED	–
60	off	off	on	on	on	on	off	off	NOT USED	–
61	on	off	on	on	on	on	off	off	NOT USED	–
62	off	on	on	on	on	on	off	off	NOT USED	–
63	on	on	on	on	on	on	off	off	NOT USED	–
64	off	off	off	off	off	off	on	off	Pinball	Stern
65	on	off	off	off	off	off	on	off	Stingray	Stern
66	off	on	off	off	off	off	on	off	Stars	Stern
67	on	on	off	off	off	off	on	off	Memory Lane	Stern
68	off	off	on	off	off	off	on	off	Lectronamo	Stern
69	on	off	on	off	off	off	on	off	Wild Fyre	Stern
70	off	on	on	off	off	off	on	off	Nugent	Stern
71	on	on	on	off	off	off	on	off	Dracula	Stern
72	off	off	off	on	off	off	on	off	Trident	Stern
73	on	off	off	on	off	off	on	off	Hot Hand	Stern
74	off	on	off	on	off	off	on	off	Magic	Stern
75	on	on	off	on	off	off	on	off	Cosmic Princess	Stern
76	off	off	on	on	off	off	on	off	Pinball	Stern Freeplay
77	on	off	on	on	off	off	on	off	Stingray	Stern Freeplay
78	off	on	on	on	off	off	on	off	Stars	Stern Freeplay
79	on	on	on	on	off	off	on	off	Memory Lane	Stern Freeplay
80	off	off	off	off	on	off	on	off	Lectronamo	Stern Freeplay
81	on	off	off	off	on	off	on	off	Wild Fyre	Stern Freeplay
82	off	on	off	off	on	off	on	off	Nugent	Stern Freeplay
83	on	on	off	off	on	off	on	off	Dracula	Stern Freeplay
84	off	off	on	off	on	off	on	off	Trident	Stern Freeplay
85	on	off	on	off	on	off	on	off	Hot Hand	Stern Freeplay
86	off	on	on	off	on	off	on	off	Magic	Stern Freeplay
87	on	on	on	off	on	off	on	off	Cosmic Princess	Stern Freeplay
88	off	off	off	on	on	off	on	off	NOT USED	–
89	on	off	off	on	on	off	on	off	NOT USED	–
90	off	on	off	on	on	off	on	off	NOT USED	–
91	on	on	off	on	on	off	on	off	NOT USED	–
92	off	off	on	on	on	off	on	off	NOT USED	–
93	on	off	on	on	on	off	on	off	NOT USED	–
94	off	on	on	on	on	off	on	off	NOT USED	–
95	on	on	on	on	on	off	on	off	NOT USED	–
96	off	off	off	off	off	on	on	off	FREEDOM	Bally
97	on	off	off	off	off	on	on	off	NIGHTRIDER	Bally
98	off	on	off	off	off	on	on	off	EVELKNIEVEL	Bally
99	on	on	off	off	off	on	on	off	EIGHTBALL	Bally
100	off	off	on	off	off	on	on	off	POWERPLAY	Bally
101	on	off	on	off	off	on	on	off	MATAHARI	Bally
102	off	on	on	off	off	on	on	off	BLACKJACK	Bally
103	on	on	on	off	off	on	on	off	STRIKES_SPARES	Bally
104	off	off	off	on	off	on	on	off	LOSTWORLD	Bally
105	on	off	off	on	off	on	on	off	6MILLIONMAN	Bally
106	off	on	off	on	off	on	on	off	PLAYBOY	Bally
107	on	on	off	on	off	on	on	off	VOLTAN	Bally
108	off	off	on	on	off	on	on	off	SUPERSONIC	Bally
109	on	off	on	on	off	on	on	off	STARTREK	Bally
110	off	on	on	on	off	on	on	off	KISS	Bally
111	on	on	on	on	off	on	on	off	PARAGON	Bally
112	off	off	off	off	on	on	on	off	HARLEMGLOBE	Bally
113	on	off	off	off	on	on	on	off	DOLLYPARTON	Bally
114	off	on	off	off	on	on	on	off	FUTURESPA	Bally
115	on	on	off	off	on	on	on	off	NITROGROUND	Bally
116	off	off	on	off	on	on	on	off	SILVERBALLMANIA	Bally
117	on	off	on	off	on	on	on	off	SPACEINVADERS	Bally
118	off	on	on	off	on	on	on	off	ROLLINGSTONES	Bally
119	on	on	on	off	on	on	on	off	MYSTIC	Bally
120	off	off	off	on	on	on	on	off	HOTDOGGIN	Bally
121	on	off	off	on	on	on	on	off	VIKING	Bally
122	off	on	off	on	on	on	on	off	SKATEBALL	Bally
123	on	on	off	on	on	on	on	off	FRONTIER	Bally
124	off	off	on	on	on	on	on	off	XENON	Bally
125	on	off	on	on	on	on	on	off	FLASHGORDON	Bally
126	off	on	on	on	on	on	on	off	8BALLDELUXE	Bally
127	on	on	on	on	on	on	on	off	FIREBALLII	Bally
128	off	off	off	off	off	off	off	on	EMRYRON	Bally
129	on	off	off	off	off	off	off	on	FATHOM	Bally
130	off	on	off	off	off	off	off	on	MEDUSA	Bally
131	on	on	off	off	off	off	off	on	CENTAUR	Bally
132	off	off	on	off	off	off	off	on	ELEKTRA	Bally
133	on	off	on	off	off	off	off	on	VECTOR	Bally
134	off	on	on	off	off	off	off	on	MR_MRSPACMAN	Bally
135	on	on	on	off	off	off	off	on	SPECTRUM	Bally
136	off	off	off	on	off	off	off	on	SPEAKEASY	Bally
137	on	off	off	on	off	off	off	on	BMX	Bally
138	off	on	off	on	off	off	off	on	GRANDSLAM	Bally 2 player
139	on	on	off	on	off	off	off	on	GOLDBALL	Bally
140	off	off	on	on	off	off	off	on	XandOs	Bally
141	on	off	on	on	off	off	off	on	SPYHUNTER	Bally
142	off	on	on	on	off	off	off	on	KINGSOFSTEEL	Bally
143	on	on	on	on	off	off	off	on	BLACKPYRAMID	Bally
144	off	off	off	off	on	off	off	on	FIREBALCLASSIC	Bally
145	on	off	off	off	on	off	off	on	CYBERNAUT	Bally
146	off	on	off	off	on	off	off	on	NIGHTRIDER	Bally Freeplay
147	on	on	off	off	on	off	off	on	EVELKNIEVEL	Bally Freeplay
148	off	off	on	off	on	off	off	on	EIGHTBALL	Bally Freeplay
149	on	off	on	off	on	off	off	on	POWERPLAY	Bally Freeplay
150	off	on	on	off	on	off	off	on	MATAHARI	Bally Freeplay
151	on	on	on	off	on	off	off	on	BLACKJACK	Bally Freeplay
152	off	off	off	on	on	off	off	on	STRIKES_SPARES	Bally Freeplay
153	on	off	off	on	on	off	off	on	LOSTWORLD	Bally Freeplay
154	off	on	off	on	on	off	off	on	6MILLIONMAN	Bally Freeplay
155	on	on	off	on	on	off	off	on	PLAYBOY	Bally Freeplay
156	off	off	on	on	on	off	off	on	VOLTAN	Bally Freeplay
157	on	off	on	on	on	off	off	on	SUPERSONIC	Bally Freeplay
158	off	on	on	on	on	off	off	on	STARTREK	Bally Freeplay
159	on	on	on	on	on	off	off	on	KISS	Bally Freeplay
160	off	off	off	off	off	on	off	on	PARAGON	Bally Freeplay
161	on	off	off	off	off	on	off	on	HARLEMGLOBE	Bally Freeplay
162	off	on	off	off	off	on	off	on	DOLLYPARTON	Bally Freeplay
163	on	on	off	off	off	on	off	on	FUTURESPA	Bally Freeplay
164	off	off	on	off	off	on	off	on	NITROGROUND	Bally Freeplay
165	on	off	on	off	off	on	off	on	SILVERBALLMANIA	Bally Freeplay
166	off	on	on	off	off	on	off	on	SPACEINVADERS	Bally Freeplay
167	on	on	on	off	off	on	off	on	ROLLINGSTONES	Bally Freeplay
168	off	off	off	on	off	on	off	on	MYSTIC	Bally Freeplay
169	on	off	off	on	off	on	off	on	HOTDOGGIN	Bally Freeplay
170	off	on	off	on	off	on	off	on	VIKING	Bally Freeplay
171	on	on	off	on	off	on	off	on	SKATEBALL	Bally Freeplay
172	off	off	on	on	off	on	off	on	FRONTIER	Bally Freeplay
173	on	off	on	on	off	on	off	on	XENON	Bally Freeplay
174	off	on	on	on	off	on	off	on	FLASHGORDON	Bally Freeplay
175	on	on	on	on	off	on	off	on	8BALLDELUXE	Bally Freeplay
176	off	off	off	off	on	on	off	on	FIREBALLII	Bally Freeplay
177	on	off	off	off	on	on	off	on	EMRYRON	Bally Freeplay
178	off	on	off	off	on	on	off	on	FATHOM	Bally Freeplay
179	on	on	off	off	on	on	off	on	MEDUSA	Bally Freeplay
180	off	off	on	off	on	on	off	on	CENTAUR	Bally Freeplay
181	on	off	on	off	on	on	off	on	ELEKTRA	Bally Freeplay
182	off	on	on	off	on	on	off	on	VECTOR	Bally Freeplay
183	on	on	on	off	on	on	off	on	MR_MRSPACMAN	Bally Freeplay
184	off	off	off	on	on	on	off	on	SPECTRUM	Bally Freeplay
185	on	off	off	on	on	on	off	on	SPEAKEASY	Bally Freeplay
186	off	on	off	on	on	on	off	on	BMX	Bally Freeplay
187	on	on	off	on	on	on	off	on	GOLDBALL	Bally Freeplay
188	off	off	on	on	on	on	off	on	XandOs	Bally Freeplay
189	on	off	on	on	on	on	off	on	SPYHUNTER	Bally Freeplay
190	off	on	on	on	on	on	off	on	KINGSOFSTEEL	Bally Freeplay
191	on	on	on	on	on	on	off	on	BLACKPYRAMID	Bally Freeplay
192	off	off	off	off	off	off	on	on	FIREBALCLASSIC	Bally Freeplay
193	on	off	off	off	off	off	on	on	CYBERNAUT	Bally Freeplay
194	off	on	off	off	off	off	on	on	6MILLIONMAN	Bally 7digit mod
195	on	on	off	off	off	off	on	on	PLAYBOY	Bally 7digit mod
196	off	off	on	off	off	off	on	on	VOLTAN	Bally 7digit mod
197	on	off	on	off	off	off	on	on	SUPERSONIC	Bally 7digit mod
198	off	on	on	off	off	off	on	on	STARTREK	Bally 7digit mod
199	on	on	on	off	off	off	on	on	KISS	Bally 7digit mod
200	off	off	off	on	off	off	on	on	PARAGON	Bally 7digit mod
201	on	off	off	on	off	off	on	on	HARLEMGLOBE	Bally 7digit mod
202	off	on	off	on	off	off	on	on	DOLLYPARTON	Bally 7digit mod
203	on	on	off	on	off	off	on	on	FUTURESPA	Bally 7digit mod
204	off	off	on	on	off	off	on	on	NITROGROUND	Bally 7digit mod
205	on	off	on	on	off	off	on	on	SILVERBALLMANIA	Bally 7digit mod
206	off	on	on	on	off	off	on	on	SPACEINVADERS	Bally 7digit mod
207	on	on	on	on	off	off	on	on	ROLLINGSTONES	Bally 7digit mod
208	off	off	off	off	on	off	on	on	MYSTIC	Bally 7digit mod
209	on	off	off	off	on	off	on	on	HOTDOGGIN	Bally 7digit mod
210	off	on	off	off	on	off	on	on	VIKING	Bally 7digit mod
211	on	on	off	off	on	off	on	on	8BALLDELUXE	Special
212	off	off	on	off	on	off	on	on	EMBRYON	Special
213	on	off	on	off	on	off	on	on	VECTOR	Special
214	off	on	on	off	on	off	on	on	FATHOM	Special
215	on	on	on	off	on	off	on	on	NITROGROUND	Special w. Sirene Patch
216	off	off	off	on	on	off	on	on	Pinball	Stern
217	on	off	off	on	on	off	on	on	Stingray	Stern
218	off	on	off	on	on	off	on	on	Stars	Stern
219	on	on	off	on	on	off	on	on	Memory Lane	Stern
220	off	off	on	on	on	off	on	on	Pinball	Stern Freeplay
221	on	off	on	on	on	off	on	on	Stingray	Stern Freeplay
222	off	on	on	on	on	off	on	on	Stars	Stern Freeplay
223	on	on	on	on	on	off	on	on	Memory Lane	Stern Freeplay
224	off	off	off	off	off	on	on	on	Tigerrag	Bell Games
225	on	off	off	off	off	on	on	on	8BALLDELUXE	V32
226	off	on	off	off	off	on	on	on	SPEAKEASY 4Player	–
227	on	on	off	off	off	on	on	on	SPEAKEASY 4Player	Freeplay
228	off	off	on	off	off	on	on	on	Saturn2	Bell Games
229	on	off	on	off	off	on	on	on	Lectronamo	Stern
230	off	on	on	off	off	on	on	on	Lectronamo	Stern Freeplay
231	on	on	on	off	off	on	on	on	World Defender	Bell Games
232	off	off	off	on	off	on	on	on	World Defender	Bell Games Freeplay
233	on	off	off	on	off	on	on	on	Baby Pacman	–
234	off	on	off	on	off	on	on	on	Baby Pacman	Okaegi version
235	on	on	off	on	off	on	on	on	GRANDSLAM	4 player
236	off	off	on	on	off	on	on	on	GRANDSLAM	2 player freeplay
237	on	off	on	on	off	on	on	on	GRANDSLAM	4 player freeplay

Appendix B Quick reference

The 14 configuration switches of SternFA

 S1  game select                       S2  options
  1  + 1                                1  zero cross emulator
  2  + 2                                2  save nvram continuously
  3  + 4                                3  force Bally clock
  4  + 8                                4  allow FA-Control to take over
  5  + 16                               5  anti flicker for LEDs
  6  + 32                               6  init nvram at boot
  7  + 64
  8  + 128                             default: all OFF

 both banks are read ONCE, at boot - after changing anything: power off, power on

S9, the 4 way bank next to socket X7, belongs to the ESP32 module, not to the FPGA (9.6).

The info display, first seconds after power on

Player 1      5 0 6     version, first digit = board variant (chapter 11)
Player 2   2    1 0 1    game select; leading 2 = Stern MPU-200 clock
Player 3   0 5 0 9 6 3   lisy.dev identifier, fixed
Player 4        3 2      value of the option bank S2 (Dip1=1 ... Dip6=32)
Credit              4    counts down 4, 3, 2, 1, 0

LEDs: red SD card error (dark = good) · yellow zero cross (lit = good) · green Bally (blinks at start, then lit while the game runs; lit continuously during an FA-Control takeover)

SD card error digit in the status display: 1 = card not readable · 2 = checksum of the game block wrong · 3 = rom came from the ESP32 (no error, HW 2.0 only) · 4 = rom from the configuration flash, no card (no error, x.30 and later) · 8 = no card, game not in the flash

Buttons: SW2 reset (FPGA board) · S6 'Bally Test' = self test · S33 bookkeeping reset · S8 belongs to the ESP32 · SW3 has no function

FPGA program for this board: SternFA_5xx - a version not starting with 5 is the wrong board. From 5.30 on only PCB v2.02 or a modified v2.00/v2.01 (chapter 13).