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/main.cpp	Fri Apr 22 17:58:35 2016 +0000
+++ b/main.cpp	Sat Apr 30 17:43:38 2016 +0000
@@ -291,9 +291,9 @@
     for (;;)
         diagLED(1, 0, 0);
-        wait(.2);
+        wait_us(200000);
         diagLED(1, 0, 1);
-        wait(.2);
+        wait_us(200000);
@@ -1713,21 +1713,212 @@
         bool waitForConnect, bool enableJoystick, bool useKB) 
         : USBJoystick(vendor_id, product_id, product_release, waitForConnect, enableJoystick, useKB)
-        suspended_ = false;
+        sleeping_ = false;
+        reconnectPending_ = false;
+        timer_.start();
+    }
+    // show diagnostic LED feedback for connect state
+    void diagFlash()
+    {
+        if (!configured() || sleeping_)
+        {
+            // flash once if sleeping or twice if disconnected
+            for (int j = isConnected() ? 1 : 2 ; j > 0 ; --j)
+            {
+                // short red flash
+                diagLED(1, 0, 0);
+                wait_us(50000);
+                diagLED(0, 0, 0);
+                wait_us(50000);
+            }
+        }
     // are we connected?
     int isConnected()  { return configured(); }
-    // Are we in suspend mode?
-    int isSuspended() const { return suspended_; }
+    // Are we in sleep mode?  If true, this means that the hardware has
+    // detected no activity on the bus for 3ms.  This happens when the
+    // cable is physically disconnected, the computer is turned off, or
+    // the connection is otherwise disabled.
+    bool isSleeping() const { return sleeping_; }
+    // If necessary, attempt to recover from a broken connection.
+    //
+    // This is a hack, to work around an apparent timing bug in the
+    // KL25Z USB implementation that I haven't been able to solve any
+    // other way.
+    //
+    // The issue: when we have an established connection, and the
+    // connection is broken by physically unplugging the cable or by
+    // rebooting the PC, the KL25Z sometimes fails to reconnect when
+    // the physical connection is re-established.  The failure is 
+    // sporadic; I'd guess it happens about 25% of the time, but I 
+    // haven't collected any real statistics on it.  
+    //
+    // The proximate cause of the failure is a deadlock in the SETUP
+    // protocol between the host and device that happens around the
+    // point where the PC is requesting the configuration descriptor.
+    // The exact point in the protocol where this occurs varies slightly;
+    // it can occur a message or two before or after the Get Config
+    // Descriptor packet.  No matter where it happens, the nature of
+    // the deadlock is the same: the PC thinks it sees a STALL on EP0
+    // from the device, so it terminates the connection attempt, which
+    // stops further traffic on the cable.  The KL25Z USB hardware sees
+    // the lack of traffic and triggers a SLEEP interrupt (a misnomer
+    // for what should have been called a BROKEN CONNECTION interrupt).
+    // Both sides simply stop talking at this point, so the connection
+    // is effectively dead.  
+    //
+    // The strange thing is that, as far as I can tell, the KL25Z isn't
+    // doing anything to trigger the STALL on its end.  Both the PC
+    // and the KL25Z are happy up until the very point of the failure 
+    // and show no signs of anything wrong in the protocol exchange.
+    // In fact, every detail of the protocol exchange up to this point
+    // is identical to every successful exchange that does finish the
+    // whole setup process successfully, on both the KL25Z and Windows
+    // sides of the connection.  I can't find any point of difference
+    // between successful and unsuccessful sequences that suggests why
+    // the fateful message fails.  This makes me suspect that whatever
+    // is going wrong is inside the KL25Z USB hardware module, which 
+    // is a pretty substantial black box - it has a lot of internal 
+    // state that's inaccessible to the software.  Further bolstering 
+    // this theory is a little experiment where I found that I could 
+    // reproduce the exact sequence of events of a failed reconnect 
+    // attempt in an *initial* connection, which is otherwise 100% 
+    // reliable, by inserting a little bit of artifical time padding 
+    // (200us per event) into the SETUP interrupt handler.  My
+    // hypothesis is that the STALL event happens because the KL25Z
+    // USB hardware is too slow to respond to a message.  I'm not 
+    // sure why this would only happen after a disconnect and not
+    // during the initial connection; maybe there's some reset work
+    // in the hardware that takes a substantial amount of time after
+    // a disconnect.
+    //
+    // The solution: the problem happens during the SETUP exchange,
+    // after we've been assigned a bus address.  It only happens on
+    // some percentage of connection requests, so if we can simply
+    // start over when the failure occurs, we'll eventually succeed
+    // simply because not every attempt fails.  The ideal would be
+    // to get the success rate up to 100%, but I can't figure out how
+    // to fix the underlying problem, so this is the next best thing.
+    //
+    // We can detect when the failure occurs by noticing when a SLEEP
+    // interrupt happens while we have an assigned bus address.
+    //
+    // To start a new connection attempt, we have to make the *host*
+    // try again.  The logical connection is initiated solely by the
+    // host.  Fortunately, it's easy to get the host to initiate the
+    // process: if we disconnect on the device side, it effectively
+    // makes the device look to the PC like it's electrically unplugged.
+    // When we reconnect on the device side, the PC thinks a new device
+    // has been plugged in and initiates the logical connection setup.
+    // We have to remain disconnected for a macroscopic interval for
+    // this to happen - 5ms seems to do the trick.
+    // 
+    // Here's the full algorithm:
+    //
+    // 1. In the SLEEP interrupt handler, if we have a bus address,
+    // we disconnect the device.  This happens in ISR context, so we
+    // can't wait around for 5ms.  Instead, we simply set a flag noting
+    // that the connection has been broken, and we note the time and
+    // return.
+    //
+    // 2. In our main loop, whenever we find that we're disconnected,
+    // we call recoverConnection().  The main loop's job is basically a
+    // bunch of device polling.  We're just one more device to poll, so
+    // recoverConnection() will be called soon after a disconnect, and
+    // then will be called in a loop for as long as we're disconnected.
+    //
+    // 3. In recoverConnection(), we check the flag we set in the SLEEP
+    // handler.  If set, we wait until 5ms has elapsed from the SLEEP
+    // event time that we noted, then we'll reconnect and clear the flag.
+    // This gives us the required 5ms (or longer) delay between the
+    // disconnect and reconnect, ensuring that the PC will notice and
+    // will start over with the connection protocol.
+    //
+    // 4. The main loop keeps calling recoverConnection() in a loop for
+    // as long as we're disconnected, so if the new connection attempt
+    // triggered in step 3 fails, the SLEEP interrupt will happen again,
+    // we'll disconnect again, the flag will get set again, and 
+    // recoverConnection() will reconnect again after another suitable
+    // delay.  This will repeat until the connection succeeds or hell
+    // freezes over.  
+    //
+    // Each disconnect happens immediately when a reconnect attempt 
+    // fails, and an entire successful connection only takes about 25ms, 
+    // so our loop can retry at more than 30 attempts per second.  
+    // In my testing, lost connections almost always reconnect in
+    // less than second with this code in place.
+    void recoverConnection()
+    {
+        // if a reconnect is pending, reconnect
+        if (reconnectPending_)
+        {
+            // Loop until we reach 5ms after the last sleep event.
+            for (bool done = false ; !done ; )
+            {
+                // If we've reached the target time, reconnect.  Do the
+                // time check and flag reset atomically, so that we can't
+                // have another sleep event sneak in after we've verified
+                // the time.  If another event occurs, it has to happen
+                // before we check, in which case it'll update the time
+                // before we check it, or after we clear the flag, in
+                // which case it will reset the flag and we'll do another
+                // round the next time we call this routine.
+                __disable_irq();
+                if (uint32_t(timer_.read_us() - lastSleepTime_) > 5000)
+                {
+                    connect(false);
+                    reconnectPending_ = false;
+                    done = true;
+                }
+                __enable_irq();
+            }
+        }
+    }
-    virtual void suspendStateChanged(unsigned int suspended)
-        { suspended_ = suspended; }
-    // are we suspended?
-    int suspended_; 
+    // Handle a USB SLEEP interrupt.  This interrupt signifies that the
+    // USB hardware module hasn't seen any token traffic for 3ms, which 
+    // means that we're either physically or logically disconnected. 
+    //
+    // Important: this runs in ISR context.
+    //
+    // Note that this is a specialized sense of "sleep" that's unrelated 
+    // to the similarly named power modes on the PC.  This has nothing
+    // to do with suspend/sleep mode on the PC, and it's not a low-power
+    // mode on the KL25Z.  They really should have called this interrupt 
+    virtual void sleepStateChanged(unsigned int sleeping)
+    { 
+        // note the new state
+        sleeping_ = sleeping;
+        // If we have a non-zero bus address, we have at least a partial
+        // connection to the host (we've made it at least as far as the
+        // SETUP stage).  Explicitly disconnect, and the pending reconnect
+        // flag, and remember the time of the sleep event.
+        if (USB0->ADDR != 0x00)
+        {
+            disconnect();
+            lastSleepTime_ = timer_.read_us();
+            reconnectPending_ = true;
+        }
+    }
+    // is the USB connection asleep?
+    volatile bool sleeping_; 
+    // flag: reconnect pending after sleep event
+    volatile bool reconnectPending_;
+    // time of last sleep event while connected
+    volatile uint32_t lastSleepTime_;
+    // timer to keep track of interval since last sleep event
+    Timer timer_;
 // ---------------------------------------------------------------------------
@@ -3003,18 +3194,6 @@
     inline void firingMode(int m) 
         firing = m;
-#if 0 // $$$   
-        lwPin[3]->set(0);
-        lwPin[4]->set(0);
-        lwPin[5]->set(0);
-        switch (m)
-        {
-        case 1: lwPin[3]->set(255); break;       // red
-        case 2: lwPin[4]->set(255); break;       // green
-        case 3: lwPin[5]->set(255); break;       // blue
-        case 4: lwPin[3]->set(255); lwPin[5]->set(255); break;   // purple
-        }
-#endif //$$$
     // Find the most recent local maximum in the history data, up to
@@ -3290,13 +3469,14 @@
 // Reboot - resets the microcontroller
-void reboot(USBJoystick &js)
+void reboot(USBJoystick &js, bool disconnect = true, long pause_us = 2000000L)
     // disconnect from USB
-    js.disconnect();
+    if (disconnect)
+        js.disconnect();
     // wait a few seconds to make sure the host notices the disconnect
-    wait(2.5f);
+    wait_us(pause_us);
     // reset the device
@@ -3734,11 +3914,10 @@
     // enable the 74HC595 chips, if present
-    // Initialize the LedWiz ports.  Note that it's important to wait until
-    // after initializing the various off-board output port controller chip
-    // sybsystems (TLC5940, 74HC595), since pins attached to peripheral
-    // controllers will need to address their respective controller objects,
-    // which don't exit until we initialize those subsystems.
+    // Initialize the LedWiz ports.  Note that the ordering here is important:
+    // this has to come after we create the TLC5940 and 74HC595 object instances
+    // (which we just did above), since we need to access those objects to set
+    // up ports assigned to the respective chips.
     // start the TLC5940 clock
@@ -3767,13 +3946,14 @@
             // short yellow flash
             diagLED(1, 1, 0);
-            wait(0.05);
+            wait_us(50000);
             diagLED(0, 0, 0);
             // reset the flash timer
+    connected = true;
     // Last report timer for the joytick interface.  We use the joystick timer 
     // to throttle the report rate, because VP doesn't benefit from reports any 
@@ -3781,8 +3961,6 @@
     Timer jsReportTimer;
-    Timer plungerIntervalTimer; plungerIntervalTimer.start(); // $$$
     // Time since we successfully sent a USB report.  This is a hacky workaround
     // for sporadic problems in the USB stack that I haven't been able to figure
     // out.  If we go too long without successfully sending a USB report, we'll
@@ -3826,7 +4004,11 @@
     // set up the ZB Launch Ball monitor
     ZBLaunchBall zbLaunchBall;
-    Timer dbgTimer; dbgTimer.start(); // $$$  plunger debug report timer
+    // enable the peripheral chips
+    if (tlc5940 != 0)
+        tlc5940->enable(true);
+    if (hc595 != 0)
+        hc595->enable(true);
     // we're all set up - now just loop, processing sensor reports and 
     // host requests
@@ -4006,12 +4188,6 @@
             // rotate X and Y according to the device orientation in the cabinet
             accelRotate(x, y);
-#if 0
-            // $$$ report velocity in x axis and timestamp in y axis
-            x = int(plungerReader.getVelocity() * 1.0 * JOYMAX);
-            y = (plungerReader.getTimestamp() / 1000) % JOYMAX;
             // send the joystick report
             jsOK = js.update(x, y, zrep, jsButtons, statusFlags);
@@ -4050,12 +4226,12 @@
         // check for connection status changes
-        bool newConnected = js.isConnected() && !js.isSuspended();
+        bool newConnected = js.isConnected() && !js.isSleeping();
         if (newConnected != connected)
-            // give it a few seconds to stabilize
+            // give it a moment to stabilize
-            if ( > 3)
+            if (connectChangeTimer.read_us() > 100000)
                 // note the new status
                 connected = newConnected;
@@ -4064,34 +4240,10 @@
-                // adjust to the new status
-                if (connected)
+                // if we're newly disconnected, clean up for PC suspend mode or power off
+                if (!connected)
-                    // We're newly connected.  This means we just powered on, we were
-                    // just plugged in to the PC USB port after being unplugged, or the
-                    // PC just came out of sleep/suspend mode and resumed the connection.
-                    // In any of these cases, we can now assume that the PC power supply
-                    // is on (the PC must be on for the USB connection to be running, and
-                    // if the PC is on, its power supply is on).  This also means that 
-                    // power to any external output controller chips (TLC5940, 74HC595)
-                    // is now on, because those have to be powered from the PC power
-                    // supply to allow for a reliable data connection to the KL25Z.
-                    // We can thus now set clear initial output state in those chips and
-                    // enable their outputs.
-                    if (tlc5940 != 0)
-                    {
-                        tlc5940->update(true);
-                        tlc5940->enable(true);
-                    }
-                    if (hc595 != 0)
-                    {
-                        hc595->update(true);
-                        hc595->enable(true);
-                    }
-                }
-                else
-                {
-                    // We're no longer connected.  Turn off all outputs.
+                    // turn off all outputs
                     // The KL25Z runs off of USB power, so we might (depending on the PC
@@ -4124,84 +4276,107 @@
         // if we're disconnected, initiate a new connection
         if (!connected)
-            // The "connected" variable means that we're either disconnected
-            // or that the connection has been suspended (e.g., the host is in 
-            // a sleep mode).  If the connection was lost entirely, explicitly
-            // initiate a reconnection.
-            if (!js.isConnected())
-                js.connect(false);
+            // show USB HAL debug events
+            extern void HAL_DEBUG_PRINTEVENTS(const char *prefix);
+            // show immediate diagnostic feedback
+            js.diagFlash();
+            // clear any previous diagnostic LED display
+            diagLED(0, 0, 0);
             // set up a timer to monitor the reboot timeout
             Timer rebootTimer;
-            // wait for reconnect or reboot
-            connectTimer.reset();
-            connectTimer.start();
-            while (!js.isConnected() || js.isSuspended())
+            // set up a timer for diagnostic displays
+            Timer diagTimer;
+            diagTimer.reset();
+            diagTimer.start();
+            // loop until we get our connection back            
+            while (!js.isConnected() || js.isSleeping())
-                // show a diagnostic flash every 2 seconds
-                if (connectTimer.read_us() > 2000000)
+                // try to recover the connection
+                js.recoverConnection();
+                // show a diagnostic flash every couple of seconds
+                if (diagTimer.read_us() > 2000000)
-                    // flash once if suspended or twice if disconnected
-                    for (int j = js.isConnected() ? 1 : 2 ; j > 0 ; --j)
-                    {
-                        // short red flash
-                        diagLED(1, 0, 0);
-                        wait(0.05f);
-                        diagLED(0, 0, 0);
-                        wait(0.05f);
-                    }
+                    // flush the USB HAL debug events, if in debug mode
+                    HAL_DEBUG_PRINTEVENTS(">NC");
+                    // show diagnostic feedback
+                    js.diagFlash();
                     // reset the flash timer
-                    connectTimer.reset();
+                    diagTimer.reset();
                 // if the disconnect reboot timeout has expired, reboot
                 if (cfg.disconnectRebootTimeout != 0 
                     && > cfg.disconnectRebootTimeout)
-                    reboot(js);
+                    reboot(js, false, 0);
+            }
+            // if we made it out of that loop alive, we're connected again!
+            connected = true;
+            HAL_DEBUG_PRINTEVENTS(">C");
+            // Enable peripheral chips and update them with current output data
+            if (tlc5940 != 0)
+            {
+                tlc5940->update(true);
+                tlc5940->enable(true);
+            }
+            if (hc595 != 0)
+            {
+                hc595->update(true);
+                hc595->enable(true);
-    // $$$
-#if 0
-        if ( > 10) {
-            dbgTimer.reset();
-            if (plungerSensor != 0 && (cfg.plunger.sensorType == PlungerType_TSL1410RS || cfg.plunger.sensorType == PlungerType_TSL1410RP))
-            {
-                PlungerSensorTSL1410R *ps = (PlungerSensorTSL1410R *)plungerSensor;
-                uint32_t nRuns;
-                uint64_t totalTime;
-                ps->ccd.getTimingStats(totalTime, nRuns);
-                printf("average plunger read time: %f ms (total=%f, n=%d)\r\n", totalTime / 1000.0f / nRuns, totalTime, nRuns);
-            }
-        }
-    // end $$$
         // provide a visual status indication on the on-board LED
         if (calBtnState < 2 && hbTimer.read_us() > 1000000) 
-            if ( > 5)
+            static int spiTimeUpdate = 0; // $$$
+            if (spiTimeUpdate++ > 10 && tlc5940 != 0) {
+                spiTimeUpdate = 0;
+                printf("Average SPI time: %lf us\r\n", double(tlc5940->spi_total_time) / tlc5940->spi_runs);
+            }
+            if (jsOKTimer.read_us() > 1000000)
                 // USB freeze - show red/yellow.
-                // Our outgoing joystick messages aren't going through, even though we
-                // think we're still connected.  This indicates that one or more of our
-                // USB endpoints have stopped working, which can happen as a result of
-                // bugs in the USB HAL or latency responding to a USB IRQ.  Show a
-                // distinctive diagnostic flash to signal the error.  I haven't found a 
-                // way to recover from this class of error other than rebooting the MCU, 
-                // so the goal is to fix the HAL so that this error never happens.  
-                // NOTE!  This diagnostic code *hopefully* shouldn't occur.  It happened
-                // in the past due to a number of bugs in the mbed KL25Z USB HAL that
-                // I've since fixed.  I think I found all of the cases that caused it,
-                // but I'm leaving the diagnostics here in case there are other bugs
-                // still lurking that can trigger the same symptoms.
-                jsOKTimer.stop();
+                // It's been more than a second since we successfully sent a joystick
+                // update message.  This must mean that something's wrong on the USB
+                // connection, even though we haven't detected an outright disconnect.
+                // Show a distinctive diagnostic LED pattern when this occurs.
                 hb = !hb;
                 diagLED(1, hb, 0);
+                // If the reboot-on-disconnect option is in effect, treat this condition
+                // as equivalent to a disconnect, since something is obviously wrong
+                // with the USB connection.  
+                if (cfg.disconnectRebootTimeout != 0)
+                {
+                    // The reboot timeout is in effect.  If we've been incommunicado for
+                    // longer than the timeout, reboot.  If we haven't reached the time
+                    // limit, keep running for now, and leave the OK timer running so 
+                    // that we can continue to monitor this.
+                    if ( > cfg.disconnectRebootTimeout)
+                        reboot(js, false, 0);
+                }
+                else
+                {
+                    // There's no reboot timer, so just keep running with the diagnostic
+                    // pattern displayed.  Since we're not waiting for any other timed
+                    // conditions in this state, stop the timer so that it doesn't 
+                    // overflow if this condition persists for a long time.
+                    jsOKTimer.stop();
+                }
             else if (cfg.plunger.enabled && !