Mike R / Mbed 2 deprecated Pinscape_Controller_V2

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 mechanical plunger, button inputs, and feedback device control.

In case you haven't heard of the idea 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 show the backglass artwork. Some cabs also include a third monitor to simulate the DMD (Dot Matrix Display) used for scoring on 1990s machines, or even an original plasma DMD. A computer (usually a Windows PC) 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 trim hardware.

It's possible to buy a pre-built virtual pinball machine, but it also makes a great 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 vpforums.org. Also visit my Pinscape Resources page for more about this project and other virtual pinball projects I'm working on.

Downloads

• 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.

Documentation

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 potentiometer (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 mouser.com 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 Aliexpress.com 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 KL25Z can only run one firmware program at a time, so if you install the Pinscape firmware on your KL25Z, it will replace and erase your existing VirtuaPin proprietary firmware. If you do this, the only way to restore your VirtuaPin firmware is to physically ship the KL25Z back to VirtuaPin and ask them to re-flash it. They don't allow you to do this at home, and they don't even allow you to back up your firmware, since they want to protect their proprietary software from copying. For all of these reasons, if you want to run the Pinscape software, I strongly recommend that you buy a "blank" retail KL25Z to use with Pinscape. They only cost about $15 and are available at several online retailers, including Amazon, Mouser, and eBay. The blank retail boards don't come with any proprietary firmware pre-installed, so installing Pinscape won't delete anything that you paid extra for.

With those warnings in mind, if you're absolutely sure that you don't mind permanently erasing your VirtuaPin firmware, it is at least possible to use Pinscape as a replacement for the VirtuaPin firmware. Pinscape uses the same button wiring conventions as the VirtuaPin setup, so you can keep your buttons (although you'll have to update the GPIO pin mappings in the Config Tool to match your physical wiring). As of the June, 2021 firmware, the Vishay VCNL4010 plunger sensor that comes with the VirtuaPin v3 plunger kit is supported, so you can also keep your plunger, if you have that chip. (You should check to be sure that's the sensor chip you have before committing to this route, if keeping the plunger sensor is important to you. The older VirtuaPin plunger kits came with different IR sensors that the Pinscape software doesn't handle.)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Plunger/quadSensor.h	Thu Apr 13 23:20:28 2017 +0000
@@ -0,0 +1,269 @@
+// AEDR-8300-1K2 optical encoder / generic quadrature sensor plunger 
+// implementation
+//
+// This class implements the Pinscape plunger interface for the 
+// AEDR-8300-1K2 optical encoder in particular, and quadrature sensors 
+// in general.  The code was written specifically for the AEDR-8300-1K2,
+// but it should work with any other quadrature sensor that's electrically 
+// compatible and that doesn't exceed the maximum interrupt rate we can 
+// handle on the KL25Z.  To be electrically compatible, the device must 
+// be 3.3V compatible, have logic type outputs (basically square waves
+// for the signals), and provide two outputs 90 degrees out of phase.  
+// The maximum interrupt rate that the KL25Z can handle (with our 
+// FastInterruptIn class) is about 150 kHz.
+//
+// A quadrature sensor works by detecting transitions along a bar-coded 
+// scale.  Most position encoders (including the AEDR-8300) are optical,
+// but the same principle can be used with other technologies, such as
+// magnetic pole strips.  Whatever the underlying physical "bar" type,
+// the device detects transitions between the bars and the spaces between
+// the bars and relays them to the microcontroller via its outputs.  A
+// quadrature device actually consists of two such sensors, slightly offset
+// from each other relative to the direction of motion of the scale, so 
+// that their bar transitions are 90 degrees out of phase.  The phase
+// shift in the two signals is what allows the microcontroller to sense
+// the direction of motion.  The controller figures the current position
+// by counting bar transitions (incrementing the count when moving in one
+// direction and decrement it in the other direction), so it knows the 
+// location at any given time as an offset in units of bar widths from the
+// starting position.  The position reading is always relative, because
+// we can only count up or down from the initial point.
+//
+// In many applications involving quadrature sensors, the relative 
+// quadrature reading is augmented with a separate sensor for absolute 
+// positioning.  This is usually something simple and low-res, like an 
+// end-of-stroke switch or a zero-crossing switch.  The idea is that you 
+// use the low-res absolute sensor to tell when you're at a known reference 
+// point, and then use the high-res quadrature data to get the precise 
+// location relative to the reference point.  To keep things simple, we 
+// don't use any such supplemental absolute sensor.  It's not really 
+// necessary for a plunger, because a plunger has the special property 
+// that it always returns to the same point when not being manipulated.  
+// It's almost as good as having a sensor at the park position, because
+// even though we can't know for sure the plunger is there at any given
+// time, it's a good bet that that's where it is at startup and any time
+// we haven't seen any motion in a while.  Note that we could easily add 
+// support in the software for some kind of absolute sensing if it became 
+// desirable; the only challenge is the complexity it would add to the
+// physical system.
+//
+// The AEDR-8300 lets us collect some very precise data on the 
+// instantaneous speed of the plunger thanks to its high resolution and
+// real-time position updates.  The shortest observed time between pulses 
+// (so far, with my test rig) is 19us.  Pulses are generated at 4 per
+// bar, with bars at 75 per inch, yielding 300 pulses per inch.  The 19us
+// pulse time translates to an instantaneous plunger speed of 0.175 
+// inches/millisecond, or 4.46 mm/ms, or 4.46 m/s, or 9.97 mph.
+//
+// The peak interrupt rate of 19us is well within the KL25Z's comfort
+// zone, as long as we take reasonable measures to minimize latency.  In
+// particular, we have to elevate the GPIO port IRQ priority above all
+// other hardware interrupts.  That's vital because there are some
+// relatively long-running interrupt handlers in the system, particularly
+// the USB handlers and the microsecond timer.  It's also vital to keep
+// other GPIO interrupt handlers very fast, since the ports all share
+// a priority level and thus can't preempt one another.  Fortunately, the
+// rest of the Pinscape system make very little use of GPIO interrupts;
+// the only current use is in the IR receiver, and that code is designed 
+// to do minimal work in IRQ context.
+//
+// We use our custom FastInterruptIn class instead of the original mbed
+// InterruptIn.  FastInterruptIn gives us a modest speed improvement: it
+// has a measured overhead time per interrupt of about 6.5us compared with
+// the mbed libary's 8.9us, which gives us a maximum interrupt rate of
+// about 159kHz vs mbed's 112kHz.  The AEDR-8300's maximum 19us is well
+// within both limits, but FastInterruptIn gives us a little more headroom
+// for substituting other sensors with higher pulse rates.
+//
+
+#ifndef _QUADSENSOR_H_
+#define _QUADSENSOR_H_
+
+#include "FastInterruptIn.h"
+
+class PlungerSensorQuad: public PlungerSensor
+{
+public:
+    // Construct.
+    //
+    // 'dpi' is the approximate number of dots per inch of linear travel
+    // that the sensor can distinguish.  This is equivalent to the number
+    // of pulses it generates per inch.  This doesn't have to be exact,
+    // since the main loop rescales it anyway via calibration.  But it's
+    // helpful to have the approximate figure so that we can scale the
+    // raw data readings appropriately for the interface datatypes.
+    PlungerSensorQuad(int dpi, PinName pinA, PinName pinB) 
+        : chA(pinA), chB(pinB)
+    {   
+        // remember the dpi setting
+        this->dpi = dpi;
+        
+        // Use 1" as the reference park position
+        parkPos = dpi;
+        
+        // Figure the scale factor for reports.  We want a 3" range to
+        // mostly cover the 16-bit unsigned range (0..65535) of the read()
+        // reports.  To leave a little cushion to avoid overflow, figure
+        // the actual factor using a 4" range.
+        posScale = 65535/(dpi*4);
+        
+        // start at the park position
+        pos = parkPos;
+          
+        // get the initial pin states
+        st = (chA.read() ? 0x01 : 0x00) 
+             | (chB.read() ? 0x02 : 0x00);
+        
+        // set up the interrupt handlers
+        chA.rise(&PlungerSensorQuad::aUp, this);
+        chA.fall(&PlungerSensorQuad::aDown, this);
+        chB.rise(&PlungerSensorQuad::bUp, this);
+        chB.fall(&PlungerSensorQuad::bDown, this);
+
+        // start our sample timer with an arbitrary zero point of now
+        timer.start();
+    }
+    
+    // Auto-zero.  Return to the park position
+    virtual void autoZero()
+    {
+        pos = parkPos;
+    }
+        
+    // Begin calibration.  We can assume that the plunger is at the
+    // park position when calibration starts.
+    virtual void beginCalibration()
+    {
+        pos = parkPos;
+    }
+    
+    // read the sensor
+    virtual bool read(PlungerReading &r)
+    {
+        // Return the current position, adjusted for our dpi scaling
+        r.pos = uint16_t(pos * posScale);
+        
+        // Set the timestamp on the reading to right now.  Our internal
+        // position counter reflects the position in real time, since it's
+        // updated in the interrupt handlers for the change signals from
+        // the sensor.
+        r.t = timer.read_us();
+        
+        // success
+        return true;
+    }
+    
+    // figure the average scan time in microseconds
+    virtual uint32_t getAvgScanTime() 
+    { 
+        // we're updated by interrupts rather than scanning, so our
+        // "scan time" is exactly zero
+        return 0;
+    }
+        
+private:
+    // interrupt inputs for our channel pins
+    FastInterruptIn chA, chB;
+    
+    // "Dots per inch" for the sensor.  This reflects the approximate
+    // number of quadrature transition pulses we expect per inch of
+    // physical travel.  This is usually a function of the "scale" 
+    // (the reference guide that the sensor moves across to sense
+    // its motion).  Quadrature sensors usually generate four pulses
+    // per "bar/window pair" on the scale, and the scale is usually
+    // measured in terms of "lines per inch" (or something analogous
+    // for non-optical sensors, such as "poles per inch" for a magnetic 
+    // sensor).  So the effective "dots per inch" is usually equal to
+    // 4x the scale marks per inch.  It's not critical for us to know
+    // the exact dpi rating, since the main loop rescales the raw 
+    // readings via its calibration mechanism, but it's helpful to
+    // know at least an approximate dpi so that the raw readings fit
+    // in the interface datatypes.
+    int dpi;
+    
+    // Position report scaling factor.  The read() interface uses 16-bit
+    // ints, so we need to report positions on a 0..65535 scale.  For
+    // maximum precision in downstream calculations, we should use as
+    // much of the range as possible, so we need to rescale our raw
+    // readings to fill the range.  We figure this based on our sensor
+    // dpi.
+    int posScale;
+    
+    // current position - this is the cumulate counter for all
+    // transitions so far
+    int pos;
+    
+    // Park position.  This is essentially arbitrary, since our readings
+    // are entirely relative, but for interface purposes we have to keep 
+    // our raw readings positive.  We need an initial park position that's
+    // non-zero so that plunger motion forward of the park position remains
+    // positive.
+    int parkPos;
+    
+    // Channel state on last read.  This is a bit vector combining
+    // the two channel states:
+    //   0x01 = channel A state
+    //   0x02 = channel B state
+    uint8_t st;
+    
+    // interrupt handlers
+    static void aUp(void *obj) { 
+        PlungerSensorQuad *self = (PlungerSensorQuad *)obj; 
+        self->transition(self->st | 0x01); 
+    }
+    static void aDown(void *obj) { 
+        PlungerSensorQuad *self = (PlungerSensorQuad *)obj; 
+        self->transition(self->st & 0x02); 
+    }
+    static void bUp(void *obj) {
+        PlungerSensorQuad *self = (PlungerSensorQuad *)obj; 
+        self->transition(self->st | 0x02); 
+    }
+    static void bDown(void *obj) { 
+        PlungerSensorQuad *self = (PlungerSensorQuad *)obj; 
+        self->transition(self->st & 0x01); 
+    }
+    
+    // Transition handler.  The interrupt handlers call this, so
+    // it's critical that this run as fast as possible.  The observed
+    // peak interrupt rate is one interrupt per 19us.  Fortunately, 
+    // our work here is simple:  we just have to count the pulse in 
+    // the appropriate direction according to the state transition 
+    // that the pulse represents.  We can do this with a simple table 
+    // lookup.
+    inline void transition(int stNew)
+    {
+        // Transition matrix: this gives the direction of motion
+        // when we switch from state dir[n] to state dir[n][m].
+        // The state number is formed by the two-bit number B:A,
+        // where each bit is 1 if the channel pulse is on and 0
+        // if the channel pulse is off.  E.g., if chA is OFF and 
+        // chB is ON, B:A = 1:0, so the state number is 0b10 = 2.
+        // Slots with 'NV' are Not Valid: it's impossible to make 
+        // this transition (unless we missed an interrupt).  'NC'
+        // means No Change; these are the slots on the matrix
+        // diagonal, which represent the same state on both input
+        // and output.  Like NV transitions, NC transitions should
+        // never happen, in this case because no interrupt should
+        // be generated when nothing has changed.
+        const int NV = 0, NC = 0;
+        static const int dir[][4] = {
+            { NC,  1, -1, NV },
+            { -1, NC, NV,  1 },
+            {  1, NV, NC, -1 },
+            { NV, -1,  1, NC }
+        };
+        
+        // increment or decrement the position counter by one notch, 
+        // according to the direction of motion implied by the transition
+        pos += dir[st][stNew];
+
+        // the new state is now the current state
+        st = stNew;
+    }
+    
+    // timer for input timestamps
+    Timer timer;
+};
+
+#endif