An I/O controller for virtual pinball machines: accelerometer nudge sensing, analog plunger input, button input encoding, LedWiz compatible output controls, and more.

Dependencies:   mbed FastIO FastPWM USBDevice

Fork of Pinscape_Controller by Mike R


This is Version 2 of the Pinscape Controller, an I/O controller for virtual pinball machines. (You can find the old version 1 software here.) Pinscape is software for the KL25Z that turns the board into a full-featured I/O controller for virtual pinball, with support for accelerometer-based nudging, a real plunger, button inputs, and feedback device control.

In case you haven't heard of the concept before, a "virtual pinball machine" is basically a video pinball simulator that's built into a real pinball machine body. A TV monitor goes in place of the pinball playfield, and a second TV goes in the backbox to serve as the "backglass" display. A third smaller monitor can serve as the "DMD" (the Dot Matrix Display used for scoring on newer machines), or you can even install a real pinball plasma DMD. A computer is hidden inside the cabinet, running pinball emulation software that displays a life-sized playfield on the main TV. The cabinet has all of the usual buttons, too, so it not only looks like the real thing, but plays like it too. That's a picture of my own machine to the right. On the outside, it's built exactly like a real arcade pinball machine, with the same overall dimensions and all of the standard pinball cabinet hardware.

A few small companies build and sell complete, finished virtual pinball machines, but I think it's more fun as a DIY project. If you have some basic wood-working skills and know your way around PCs, you can build one from scratch. The computer part is just an ordinary Windows PC, and all of the pinball emulation can be built out of free, open-source software. In that spirit, the Pinscape Controller is an open-source software/hardware project that offers a no-compromises, all-in-one control center for all of the unique input/output needs of a virtual pinball cabinet. If you've been thinking about building one of these, but you're not sure how to connect a plunger, flipper buttons, lights, nudge sensor, and whatever else you can think of, this project might be just what you're looking for.

You can find much more information about DIY Pin Cab building in general in the Virtual Cabinet Forum on Also visit my Pinscape Resources page for more about this project and other virtual pinball projects I'm working on.


  • Pinscape Release Builds: This page has download links for all of the Pinscape software. To get started, install and run the Pinscape Config Tool on your Windows computer. It will lead you through the steps for installing the Pinscape firmware on the KL25Z.
  • Config Tool Source Code. The complete C# source code for the config tool. You don't need this to run the tool, but it's available if you want to customize anything or see how it works inside.


The new Version 2 Build Guide is now complete! This new version aims to be a complete guide to building a virtual pinball machine, including not only the Pinscape elements but all of the basics, from sourcing parts to building all of the hardware.

You can also refer to the original Hardware Build Guide (PDF), but that's out of date now, since it refers to the old version 1 software, which was rather different (especially when it comes to configuration).

System Requirements

The new config tool requires a fairly up-to-date Microsoft .NET installation. If you use Windows Update to keep your system current, you should be fine. A modern version of Internet Explorer (IE) is required, even if you don't use it as your main browser, because the config tool uses some system components that Microsoft packages into the IE install set. I test with IE11, so that's known to work. IE8 doesn't work. IE9 and 10 are unknown at this point.

The Windows requirements are only for the config tool. The firmware doesn't care about anything on the Windows side, so if you can make do without the config tool, you can use almost any Windows setup.

Main Features

Plunger: The Pinscape Controller started out as a "mechanical plunger" controller: a device for attaching a real pinball plunger to the video game software so that you could launch the ball the natural way. This is still, of course, a central feature of the project. The software supports several types of sensors: a high-resolution optical sensor (which works by essentially taking pictures of the plunger as it moves); a slide potentionmeter (which determines the position via the changing electrical resistance in the pot); a quadrature sensor (which counts bars printed on a special guide rail that it moves along); and an IR distance sensor (which determines the position by sending pulses of light at the plunger and measuring the round-trip travel time). The Build Guide explains how to set up each type of sensor.

Nudging: The KL25Z (the little microcontroller that the software runs on) has a built-in accelerometer. The Pinscape software uses it to sense when you nudge the cabinet, and feeds the acceleration data to the pinball software on the PC. This turns physical nudges into virtual English on the ball. The accelerometer is quite sensitive and accurate, so we can measure the difference between little bumps and hard shoves, and everything in between. The result is natural and immersive.

Buttons: You can wire real pinball buttons to the KL25Z, and the software will translate the buttons into PC input. You have the option to map each button to a keyboard key or joystick button. You can wire up your flipper buttons, Magna Save buttons, Start button, coin slots, operator buttons, and whatever else you need.

Feedback devices: You can also attach "feedback devices" to the KL25Z. Feedback devices are things that create tactile, sound, and lighting effects in sync with the game action. The most popular PC pinball emulators know how to address a wide variety of these devices, and know how to match them to on-screen action in each virtual table. You just need an I/O controller that translates commands from the PC into electrical signals that turn the devices on and off. The Pinscape Controller can do that for you.

Expansion Boards

There are two main ways to run the Pinscape Controller: standalone, or using the "expansion boards".

In the basic standalone setup, you just need the KL25Z, plus whatever buttons, sensors, and feedback devices you want to attach to it. This mode lets you take advantage of everything the software can do, but for some features, you'll have to build some ad hoc external circuitry to interface external devices with the KL25Z. The Build Guide has detailed plans for exactly what you need to build.

The other option is the Pinscape Expansion Boards. The expansion boards are a companion project, which is also totally free and open-source, that provides Printed Circuit Board (PCB) layouts that are designed specifically to work with the Pinscape software. The PCB designs are in the widely used EAGLE format, which many PCB manufacturers can turn directly into physical boards for you. The expansion boards organize all of the external connections more neatly than on the standalone KL25Z, and they add all of the interface circuitry needed for all of the advanced software functions. The big thing they bring to the table is lots of high-power outputs. The boards provide a modular system that lets you add boards to add more outputs. If you opt for the basic core setup, you'll have enough outputs for all of the toys in a really well-equipped cabinet. If your ambitions go beyond merely well-equipped and run to the ridiculously extravagant, just add an extra board or two. The modular design also means that you can add to the system over time.

Expansion Board project page

Update notes

If you have a Pinscape V1 setup already installed, you should be able to switch to the new version pretty seamlessly. There are just a couple of things to be aware of.

First, the "configuration" procedure is completely different in the new version. Way better and way easier, but it's not what you're used to from V1. In V1, you had to edit the project source code and compile your own custom version of the program. No more! With V2, you simply install the standard, pre-compiled .bin file, and select options using the Pinscape Config Tool on Windows.

Second, if you're using the TSL1410R optical sensor for your plunger, there's a chance you'll need to boost your light source's brightness a little bit. The "shutter speed" is faster in this version, which means that it doesn't spend as much time collecting light per frame as before. The software actually does "auto exposure" adaptation on every frame, so the increased shutter speed really shouldn't bother it, but it does require a certain minimum level of contrast, which requires a certain minimal level of lighting. Check the plunger viewer in the setup tool if you have any problems; if the image looks totally dark, try increasing the light level to see if that helps.

New Features

V2 has numerous new features. Here are some of the highlights...

Dynamic configuration: as explained above, configuration is now handled through the Config Tool on Windows. It's no longer necessary to edit the source code or compile your own modified binary.

Improved plunger sensing: the software now reads the TSL1410R optical sensor about 15x faster than it did before. This allows reading the sensor at full resolution (400dpi), about 400 times per second. The faster frame rate makes a big difference in how accurately we can read the plunger position during the fast motion of a release, which allows for more precise position sensing and faster response. The differences aren't dramatic, since the sensing was already pretty good even with the slower V1 scan rate, but you might notice a little better precision in tricky skill shots.

Keyboard keys: button inputs can now be mapped to keyboard keys. The joystick button option is still available as well, of course. Keyboard keys have the advantage of being closer to universal for PC pinball software: some pinball software can be set up to take joystick input, but nearly all PC pinball emulators can take keyboard input, and nearly all of them use the same key mappings.

Local shift button: one physical button can be designed as the local shift button. This works like a Shift button on a keyboard, but with cabinet buttons. It allows each physical button on the cabinet to have two PC keys assigned, one normal and one shifted. Hold down the local shift button, then press another key, and the other key's shifted key mapping is sent to the PC. The shift button can have a regular key mapping of its own as well, so it can do double duty. The shift feature lets you access more functions without cluttering your cabinet with extra buttons. It's especially nice for less frequently used functions like adjusting the volume or activating night mode.

Night mode: the output controller has a new "night mode" option, which lets you turn off all of your noisy devices with a single button, switch, or PC command. You can designate individual ports as noisy or not. Night mode only disables the noisemakers, so you still get the benefit of your flashers, button lights, and other quiet devices. This lets you play late into the night without disturbing your housemates or neighbors.

Gamma correction: you can designate individual output ports for gamma correction. This adjusts the intensity level of an output to make it match the way the human eye perceives brightness, so that fades and color mixes look more natural in lighting devices. You can apply this to individual ports, so that it only affects ports that actually have lights of some kind attached.

IR Remote Control: the controller software can transmit and/or receive IR remote control commands if you attach appropriate parts (an IR LED to send, an IR sensor chip to receive). This can be used to turn on your TV(s) when the system powers on, if they don't turn on automatically, and for any other functions you can think of requiring IR send/receive capabilities. You can assign IR commands to cabinet buttons, so that pressing a button on your cabinet sends a remote control command from the attached IR LED, and you can have the controller generate virtual key presses on your PC in response to received IR commands. If you have the IR sensor attached, the system can use it to learn commands from your existing remotes.

Yet more USB fixes: I've been gradually finding and fixing USB bugs in the mbed library for months now. This version has all of the fixes of the last couple of releases, of course, plus some new ones. It also has a new "last resort" feature, since there always seems to be "just one more" USB bug. The last resort is that you can tell the device to automatically reboot itself if it loses the USB connection and can't restore it within a given time limit.

More Downloads

  • Custom VP builds: I created modified versions of Visual Pinball 9.9 and Physmod5 that you might want to use in combination with this controller. The modified versions have special handling for plunger calibration specific to the Pinscape Controller, as well as some enhancements to the nudge physics. If you're not using the plunger, you might still want it for the nudge improvements. The modified version also works with any other input controller, so you can get the enhanced nudging effects even if you're using a different plunger/nudge kit. The big change in the modified versions is a "filter" for accelerometer input that's designed to make the response to cabinet nudges more realistic. It also makes the response more subdued than in the standard VP, so it's not to everyone's taste. The downloads include both the updated executables and the source code changes, in case you want to merge the changes into your own custom version(s).

    Note! These features are now standard in the official VP releases, so you don't need my custom builds if you're using 9.9.1 or later and/or VP 10. I don't think there's any reason to use my versions instead of the latest official ones, and in fact I'd encourage you to use the official releases since they're more up to date, but I'm leaving my builds available just in case. In the official versions, look for the checkbox "Enable Nudge Filter" in the Keys preferences dialog. My custom versions don't include that checkbox; they just enable the filter unconditionally.
  • Output circuit shopping list: This is a saved shopping cart at with the parts needed to build one copy of the high-power output circuit for the LedWiz emulator feature, for use with the standalone KL25Z (that is, without the expansion boards). The quantities in the cart are for one output channel, so if you want N outputs, simply multiply the quantities by the N, with one exception: you only need one ULN2803 transistor array chip for each eight output circuits. If you're using the expansion boards, you won't need any of this, since the boards provide their own high-power outputs.
  • Cary Owens' optical sensor housing: A 3D-printable design for a housing/mounting bracket for the optical plunger sensor, designed by Cary Owens. This makes it easy to mount the sensor.
  • Lemming77's potentiometer mounting bracket and shooter rod connecter: Sketchup designs for 3D-printable parts for mounting a slide potentiometer as the plunger sensor. These were designed for a particular slide potentiometer that used to be available from an seller but is no longer listed. You can probably use this design as a starting point for other similar devices; just check the dimensions before committing the design to plastic.

Copyright and License

The Pinscape firmware is copyright 2014, 2021 by Michael J Roberts. It's released under an MIT open-source license. See License.

Warning to VirtuaPin Kit Owners

This software isn't designed as a replacement for the VirtuaPin plunger kit's firmware. If you bought the VirtuaPin kit, I recommend that you don't install this software. The VirtuaPin kit uses the same KL25Z microcontroller that Pinscape uses, but the rest of its hardware is different and incompatible. In particular, the Pinscape firmware doesn't include support for the IR proximity sensor used in the VirtuaPin plunger kit, so you won't be able to use your plunger device with the Pinscape firmware. In addition, the VirtuaPin setup uses a different set of GPIO pins for the button inputs from the Pinscape defaults, so if you do install the Pinscape firmware, you'll have to go into the Config Tool and reassign all of the buttons to match the VirtuaPin wiring.

--- a/Plunger/plunger.h	Fri Apr 14 17:56:54 2017 +0000
+++ b/Plunger/plunger.h	Fri Apr 21 18:50:37 2017 +0000
@@ -33,7 +33,20 @@
 class PlungerSensor
-    PlungerSensor() { }
+    PlungerSensor(int nativeScale)
+    {
+        // use the joystick scale as our native scale by default
+        this->nativeScale = nativeScale;
+        // figure the scaling factor
+        scalingFactor = (65535UL*65536UL) / nativeScale;
+        // presume no jitter filter
+        jfWindow = 0;
+        // initialize the jitter filter
+        jfLo = jfHi = jfLast = 0;
+    }
     // ---------- Abstract sensor interface ----------
@@ -62,40 +75,52 @@
     // Read the sensor position, if possible.  Returns true on success,
     // false if it wasn't possible to take a reading.  On success, fills
-    // in 'r' with the current reading.
+    // in 'r' with the current reading and timestamp and returns true.
+    // Returns false if a reading couldn't be taken.
-    // r.pos is set to the current raw sensor reading, normalized to the
-    // range 0x0000..0xFFFF.  r.t is set to the timestamp of the reading,
-    // in microseconds.
+    // r.pos is set to the normalized position reading, and r.t is set to
+    // the timestamp of the reading.
-    // Also sets r.t to the microsecond timestamp of the reading, if a
-    // reading was successfully taken.  This timestamp is relative to an
-    // arbitrary zero point and rolls over when it overflows its 32-bit
-    // container (every 71.58 minutes).  Callers can use this to calculate
-    // the interval between two readings (e.g., to figure the average 
-    // velocity of the plunger between readings).
+    // The normalized position is the sensor reading, corrected for jitter,
+    // and adjusted to the abstract 0x0000..0xFFFF range.
+    // 
+    // The timestamp is the time the sensor reading was taken, relative to
+    // an arbitrary zero point.  The arbitrary zero point makes this useful
+    // only for calculating the time between readings.  Note that the 32-bit
+    // timestamp rolls over about every 71 minutes, so it should only be
+    // used for time differences between readings taken fairly close together.
+    // In practice, the higher level code only uses this for a few consecutive
+    // readings to calculate (nearly) instantaneous velocities, so the time
+    // spans are only tens of milliseconds.
     // Timing requirements:  for best results, readings should be taken
-    // in well under 5ms.  There are two factors that go into this limit.
-    // The first is the joystick report rate in the main loop.  We want
-    // to send those as fast as possible to avoid any perceptible control 
-    // input lag in the pinball emulation.  "As fast as possible" is about
-    // every 10ms - that's VP's approximate sampling rate, so any faster
-    // wouldn't do any good, and could even slow things down by adding CPU 
-    // load in the Windows drivers handling the extra messages.  The second
-    // is the speed of the plunger motion.  During release events, the
-    // plunger moves in a sinusoidal pattern (back and forth) as it reaches
-    // the extreme of its travel and bounces back off the spring.  To
-    // resolve this kind of cyclical motion accurately, we have to take
-    // samples much faster than the cycle period - otherwise we encounter
-    // an effect known as aliasing, where we mistake a bounce for a small
-    // forward motion.  Tests with real plungers indicate that the bounce
-    // period is on the order of 10ms, so ideally we'd like to take
-    // samples much faster than that.
-    //
-    // Returns true on success, false on failure.  Returning false means
-    // that it wasn't possible to take a valid reading.
-    virtual bool read(PlungerReading &r) = 0;
+    // in well under 5ms.  The release motion of the physical plunger
+    // takes from 30ms to 50ms, so we need to collect samples much faster
+    // than that to avoid aliasing during the bounce.
+    bool read(PlungerReading &r)
+    {
+        // get the raw reading
+        if (readRaw(r))
+        {
+            // process it through the jitter filter
+            //$$$ r.pos = jitterFilter(r.pos);
+            // adjust to the abstract scale via the scaling factor
+            r.pos = uint16_t(uint32_t((scalingFactor * r.pos) + 32768) >> 16);
+            // success
+            return true;
+        }
+        else
+        {
+            // no reading is available
+            return false;
+        }
+    }
+    // Get a raw plunger reading.  This gets the raw sensor reading with
+    // timestamp, without jitter filtering and without any scale adjustment.
+    virtual bool readRaw(PlungerReading &r) = 0;
     // Begin calibration.  The main loop calls this when the user activates
     // calibration mode.  Sensors that work in terms of relative positions,
@@ -138,28 +163,105 @@
         // read the current position
         int pos = 0xFFFF;
         PlungerReading r;
-        if (read(r))
+        if (readRaw(r))
-            // success - scale it to 0..4095 (the generic scale used
-            // for non-imaging sensors)
-            pos = int(r.pos*4095L / 65535L);
+            // success - apply the jitter filter
+            pos = jitterFilter(r.pos);
         // Send the common status information, indicating 0 pixels, standard
         // sensor orientation, and zero processing time.  Non-imaging sensors 
-        // usually don't have any way to detect the orientation, so they have 
-        // to rely on being installed in a pre-determined direction.  Non-
-        // imaging sensors usually have negligible analysis time (the only
-        // "analysis" is usually nothing more than a multiply to rescale an 
-        // ADC sample), so there's no point in collecting actual timing data; 
-        // just report zero.
-        js.sendPlungerStatus(0, pos, 1, getAvgScanTime(), 0);
+        // usually don't have any way to detect the orientation, so assume
+        // normal orientation (flag 0x01).  Also assume zero analysis time,
+        // as most non-image sensors don't have to do anything CPU-intensive
+        // with the raw readings (all they usually have to do is scale the
+        // value to the abstract reporting range).
+        js.sendPlungerStatus(0, pos, 0x01, getAvgScanTime(), 0);
+        js.sendPlungerStatus2(nativeScale, jfLo, jfHi, r.pos, 0);
     // Get the average sensor scan time in microseconds
     virtual uint32_t getAvgScanTime() = 0;
+    // Apply the jitter filter
+    int jitterFilter(int pos)
+    {
+        // Check to see where the new reading is relative to the
+        // current window
+        if (pos < jfLo)
+        {
+            // the new position is below the current window, so move
+            // the window down such that the new point is at the bottom 
+            // of the window
+            jfLo = pos;
+            jfHi = pos + jfWindow;
+            jfLast = pos;
+            return pos;
+        }
+        else if (pos > jfHi)
+        {
+            // the new position is above the current window, so move
+            // the window up such that the new point is at the top of
+            // the window
+            jfHi = pos;
+            jfLo = pos - jfWindow;
+            jfLast = pos;
+            return pos;
+        }
+        else
+        {
+            // the new position is inside the current window, so repeat
+            // the last reading
+            return jfLast;
+        }
+    }
+    // Set the jitter filter window size.  This is specified in native
+    // sensor units.
+    void setJitterWindow(int w)
+    {
+        // set the new window size
+        jfWindow = w;
+        // reset the running window
+        jfHi = jfLo = jfLast;
+    }
+    // Native scale of the device.  This is the scale used for the position
+    // reading in status reports.  This lets us report the position in the
+    // same units the sensor itself uses, to avoid any rounding error 
+    // converting to an abstract scale.
+    //
+    // Image edge detection sensors use the pixel size of the image, since
+    // the position is determined by the pixel position of the shadow in
+    // the image.  Quadrature sensors and other sensors that report the
+    // distance in terms of physical distance units should use the number
+    // of quanta in the approximate total plunger travel distance of 3".
+    // For example, the VL6180X uses millimeter quanta, so can report
+    // about 77 quanta over 3"; a quadrature sensor that reports at 1/300"
+    // intervals has about 900 quanta over 3".  Absolute encoders (e.g., 
+    // bar code sensors) should use the bar code range.
+    //
+    // Sensors that are inherently analog (e.g., potentiometers, analog
+    // distance sensors) can quantize on any arbitrary scale.  In most cases,
+    // it's best to use the same 0..65535 scale used for the regular plunger
+    // reports.
+    uint16_t nativeScale;
+    // Scaling factor to convert native readings to abstract units on the
+    // 0x0000..0xFFFF scale used in the higher level sensor-independent
+    // code.  Multiply a raw sensor position reading by this value to
+    // get the equivalent value on the abstract scale.  This is expressed 
+    // as a fixed-point real number with a scale of 65536: calculate it as
+    //
+    //   (65535U*65536U) / (nativeScale - 1);
+    uint32_t scalingFactor;
+    // Jitter filtering
+    int jfWindow;                // window size, in native sensor units
+    int jfLo, jfHi;              // bounds of current window
+    int jfLast;                  // last filtered reading
 #endif /* PLUNGER_H */