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.

diff -r fd77a6b2f76c -r 4db125cd11a0 USBProtocol.h
--- a/USBProtocol.h	Sat Apr 30 17:43:38 2016 +0000
+++ b/USBProtocol.h	Wed May 04 03:59:44 2016 +0000
@@ -18,7 +18,9 @@
 // plug-and-play installation experience on Windows.  Our joystick report
 // looks like this (see USBJoystick.cpp for the formal HID report descriptor):
-//    ss     status bits:  0x01 -> plunger enabled
+//    ss     status bits:  
+//              0x01 -> plunger enabled
+//              0x02 -> night mode engaged
 //    00     2nd byte of status (reserved)
 //    00     3rd byte of status (reserved)
 //    00     always zero for joystick reports
@@ -377,8 +379,8 @@
 //                     if the value wasn't patched at install time.
 //        8 -> Engage/disengage night mode.  The third byte of the message is 1 to
-//             engage night mode, 0 to disengage night mode.  (This mode isn't stored
-//             persistently; night mode is disengaged after a reset or power cycle.)
+//             engage night mode, 0 to disengage night mode.  The current mode isn't 
+//             stored persistently; night mode is always off after a reset.
 //        9 -> Query configuration variable.  The second byte is the config variable
 //             number (see the CONFIGURATION VARIABLES section below).  For the array
@@ -446,6 +448,8 @@
 // Message type 66 (see above) sets one configuration variable.  The second byte
 // of the message is the variable ID, and the rest of the bytes give the new
 // value, in a variable-specific format.  16-bit values are little endian.
+// Any bytes at the end of the message not otherwise specified are reserved
+// for future use and should always be set to 0 in the message data.
 // 0  -> QUERY ONLY: Describe the configuration variables.  The device
 //       sends a config variable query report with the following fields:
@@ -493,72 +497,103 @@
 //         byte 3 -> unit number, from 1 to 16
-// 3  -> Enable/disable joystick reports.  Byte 2 is 1 to enable, 0 to
-//       disable.  When disabled, the device registers as a generic HID 
-/        device, and only sends the private report types used by the
-//       Windows config tool.
+// 3  -> Enable/disable joystick reports.  
+//         byte 2 -> 1 to enable, 0 to disable
-// 4  -> Accelerometer orientation.  Byte 3 is the new setting:
-//        0 = ports at front (USB ports pointing towards front of cabinet)
-//        1 = ports at left
-//        2 = ports at right
-//        3 = ports at rear
+//       When joystick reports are disabled, the device registers as a generic HID 
+//       device, and only sends the private report types used by the Windows config 
+//       tool.  It won't appear to Windows as a USB game controller or joystick.
+//       Note that this doesn't affect whether the device also registers a keyboard
+//       interface.  A keyboard interface will appear if and only if any buttons
+//       (including virtual buttons, such as the ZB Launch Ball feature) are assigned 
+//       to generate keyboard key input.
+// 4  -> Accelerometer orientation.
-// 5  -> Plunger sensor type.  Byte 3 is the type ID:
+//        byte 3 -> orientation:
+//           0 = ports at front (USB ports pointing towards front of cabinet)
+//           1 = ports at left
+//           2 = ports at right
+//           3 = ports at rear
+// 5  -> Plunger sensor type.
-//         0 = none (disabled)
-//         1 = TSL1410R linear image sensor, 1280x1 pixels, serial mode
-//        *2 = TSL1410R, parallel mode
-//         3 = TSL1412R linear image sensor, 1536x1 pixels, serial mode
-//        *4 = TSL1412R, parallel mode
-//         5 = Potentiometer with linear taper, or any other device that
-//             represents the position reading with a single analog voltage
-//        *6 = AEDR8300 optical quadrature sensor, 75lpi
-//        *7 = AS5304 magnetic quadrature sensor, 160 steps per 2mm
+//        byte 3 -> plunger type:
+//           0 = none (disabled)
+//           1 = TSL1410R linear image sensor, 1280x1 pixels, serial mode
+//          *2 = TSL1410R, parallel mode
+//           3 = TSL1412R linear image sensor, 1536x1 pixels, serial mode
+//          *4 = TSL1412R, parallel mode
+//           5 = Potentiometer with linear taper, or any other device that
+//               represents the position reading with a single analog voltage
+//          *6 = AEDR8300 optical quadrature sensor, 75lpi
+//          *7 = AS5304 magnetic quadrature sensor, 160 steps per 2mm
+//       * The sensor types marked with asterisks (*) are reserved for types
+//       that aren't currently implemented but could be added in the future.  
+//       Selecting these types will effectively disable the plunger.  
+// 6  -> Plunger pin assignments.
-//       * The sensor types marked with asterisks (*) are planned but not 
-//       currently implemented.  Selecting these types will effectively
-//       disable the plunger.
+//         byte 3 -> pin assignment 1
+//         byte 4 -> pin assignment 2
+//         byte 5 -> pin assignment 3
+//         byte 6 -> pin assignment 4
+//       All of the pins use the standard GPIO port format (see "GPIO pin number
+//       mappings" below).  The actual use of the four pins depends on the plunger
+//       type, as shown below.  "NC" means that the pin isn't used at all for the
+//       corresponding plunger type.
-// 6  -> Plunger pin assignments.  Bytes 3-6 give the pin assignments for
-//       pins 1, 2, 3, and 4.  These use the Pin Number Mappings listed
-//       below.  The meaning of each pin depends on the plunger type:
+//         Plunger Type              Pin 1            Pin 2             Pin 3           Pin 4
-//         TSL1410R/1412R, serial:    SI (DigitalOut), CLK (DigitalOut), AO (AnalogIn),  NC
-//         TSL1410R/1412R, parallel:  SI (DigitalOut), CLK (DigitalOut), AO1 (AnalogIn), AO2 (AnalogIn)
-//         Potentiometer:             AO (AnalogIn),   NC,               NC,             NC
-//         AEDR8300:                  A (InterruptIn), B (InterruptIn),  NC,             NC
-//         AS5304:                    A (InterruptIn), B (InterruptIn),  NC,             NC
+//         TSL1410R/1412R, serial    SI (DigitalOut)  CLK (DigitalOut)  AO (AnalogIn)   NC
+//         TSL1410R/1412R, parallel  SI (DigitalOut)  CLK (DigitalOut)  AO1 (AnalogIn)  AO2 (AnalogIn)
+//         Potentiometer             AO (AnalogIn)    NC                NC              NC
+//         AEDR8300                  A (InterruptIn)  B (InterruptIn)   NC              NC
+//         AS5304                    A (InterruptIn)  B (InterruptIn)   NC              NC
+// 7  -> Plunger calibration button pin assignments.
-// 7  -> Plunger calibration button pin assignments.  Byte 3 is the DigitalIn
-//       pin for the button switch; byte 4 is the DigitalOut pin for the indicator
-//       lamp.  Either can be set to NC to disable the function.  (Use the Pin
-//       Number Mappins listed below for both bytes.)
+//         byte 3 -> features enabled/disabled: bit mask consisting of:
+//                   0x01  button input is enabled
+//                   0x02  lamp output is enabled
+//         byte 4 -> DigitalIn pin for the button switch
+//         byte 5 -> DigitalOut pin for the indicator lamp
+//       Note that setting a pin to NC (Not Connected) will disable it even if the
+//       corresponding feature enable bit (in byte 3) is set.
-// 8  -> ZB Launch Ball setup.  This configures the ZB Launch Ball feature.  Byte
-//       3 is the LedWiz port number (1-255) mapped to the "ZB Launch Ball" output
-//       in DOF.  Set the port to 0 to disable the feature.   Byte 4 is the key type
-//       and byte 5 is the key code for the key to send to the PC when a launch is
-//       triggered.  These have the same meanings as for a regular key mapping.  For
-//       example, set type=2 and code=0x28 for the keyboard Enter key.  Bytes 6-7
-//       give the "push distance" for activating the button by pushing forward on
-//       the plunger knob, in 1/1000 inch increments (e.g., 63 represents 0.063", 
-//       or about 1/16", which is the recommended setting).
+// 8  -> ZB Launch Ball setup.  This configures the ZB Launch Ball feature.
+//         byte 3    -> LedWiz port number (1-255) mapped to "ZB Launch Ball" in DOF
+//         byte 4    -> key type
+//         byte 5    -> key code
+//         bytes 6:7 -> "push" distance, in 1/1000 inch increments (16 bit little endian)
+//       Set the port number to 0 to disable the feature.  The key type and key code
+//       fields use the same conventions as for a button mapping (see below).  The
+//       recommended push distance is 63, which represents .063" ~ 1/16".
 // 9  -> TV ON relay setup.  This requires external circuitry implemented on the
 //       Expansion Board (or an equivalent circuit as described in the Build Guide).
-//       Byte 3 is the GPIO DigitalIn pin for the "power status" input, using the 
-//       Pin Number Mappings below.  Byte 4 is the DigitalOut pin for the "latch"
-//       output.  Byte 5 is the DigitalOut pin for the relay trigger.  Bytes 6-7
-//       give the delay time in 10ms increments as an unsigned 16-bit value (e.g.,
-//       550 represents 5.5 seconds).  
+//         byte 3    -> "power status" input pin (DigitalIn)
+//         byte 4    -> "latch" output (DigitalOut)
+//         byte 5    -> relay trigger output (DigitalOut)
+//         bytes 6:7 -> delay time in 10ms increments (16 bit little endian);
+//                      e.g., 550 (0x26 0x02) represents 5.5 seconds
+//       Set the delay time to 0 to disable the feature.  The pin assignments will
+//       be ignored if the feature is disabled.
 // 10 -> TLC5940NT setup.  This chip is an external PWM controller, with 32 outputs
 //       per chip and a serial data interface that allows the chips to be daisy-
 //       chained.  We can use these chips to add an arbitrary number of PWM output 
-//       ports for the LedWiz emulation.  Set the number of chips to 0 to disable
-//       the feature.  The bytes of the message are:
+//       ports for the LedWiz emulation.
 //          byte 3 = number of chips attached (connected in daisy chain)
 //          byte 4 = SIN pin - Serial data (must connect to SPIO MOSI -> PTC6 or PTD2)
 //          byte 5 = SCLK pin - Serial clock (must connect to SPIO SCLK -> PTC5 or PTD1)
@@ -566,26 +601,34 @@
 //          byte 7 = BLANK pin - BLANK signal (any GPIO pin)
 //          byte 8 = GSCLK pin - Grayscale clock signal (must be a PWM-out capable pin)
+//       Set the number of chips to 0 to disable the feature.  The pin assignments are 
+//       ignored if the feature is disabled.
 // 11 -> 74HC595 setup.  This chip is an external shift register, with 8 outputs per
 //       chip and a serial data interface that allows daisy-chaining.  We use this
 //       chips to add extra digital outputs for the LedWiz emulation.  In particular,
 //       the Chime Board (part of the Expansion Board suite) uses these to add timer-
-//       protected outputs for coil devices (knockers, chimes, bells, etc).  Set the
-//       number of chips to 0 to disable the feature.  The message bytes are:
+//       protected outputs for coil devices (knockers, chimes, bells, etc).
 //          byte 3 = number of chips attached (connected in daisy chain)
 //          byte 4 = SIN pin - Serial data (any GPIO pin)
 //          byte 5 = SCLK pin - Serial clock (any GPIO pin)
 //          byte 6 = LATCH pin - LATCH signal (any GPIO pin)
 //          byte 7 = ENA pin - ENABLE signal (any GPIO pin)
+//       Set the number of chips to 0 to disable the feature.  The pin assignments are
+//       ignored if the feature is disabled.
 // 12 -> Disconnect reboot timeout.  The reboot timeout allows the controller software
 //       to automatically reboot the KL25Z after it detects that the USB connection is
 //       broken.  On some hosts, the device isn't able to reconnect after the initial
 //       connection is lost.  The reboot timeout is a workaround for these cases.  When
 //       the software detects that the connection is no longer active, it will reboot
 //       the KL25Z automatically if a new connection isn't established within the
-//       timeout period.  Bytes 3 give the new reboot timeout in seconds.  Setting this
-//       to 0 disables the reboot timeout.
+//       timeout period.  Set the timeout to 0 to disable the feature (i.e., the device
+//       will never automatically reboot itself on a broken connection).
+//          byte 3 -> reboot timeout in seconds; 0 = disabled
 // 13 -> Plunger calibration.  In most cases, the calibration is set internally by the
 //       device by running the calibration procedure.  However, it's sometimes useful
@@ -616,24 +659,31 @@
 //                  for the board changes.  It only changes when a revision is made
 //                  that affects the software, such as a GPIO pin assignment.
-//         The remaining bytes depend on the board set type.  Currently, only
-//         the Pinscape expansion boards are supported; for those, the bytes are
-//         used to store these values:
+//                  For Pinscape expansion boards (board set type = 1):
+//                    0 = first release (Feb 2016)
-//         byte 5 = number of main interface boards
-//         byte 6 = number of MOSFET power boards
-//         byte 7 = number of chime boards
+//         bytes 5:8 = additional hardware-specific data.  These slots are used
+//                  to store extra data specific to the expansion boards selected.
+//                  For Pinscape expansion boards (board set type = 1):
+//                    byte 5 = number of main interface boards
+//                    byte 6 = number of MOSFET power boards
+//                    byte 7 = number of chime boards
 // 15 -> Night mode setup.  
 //       byte 3 = button number - 1..MAX_BUTTONS, or 0 for none.  This selects
 //                a physically wired button that can be used to control night mode.
 //                The button can also be used as normal for PC input if desired.
+//                Note that night mode can still be activated via a USB command
+//                even if no button is assigned.
 //       byte 4 = flags:
 //                0x01 -> the wired input is an on/off switch; night mode will be
 //                        active when the input is switched on.  If this bit isn't
 //                        set, the input is a momentary button; pushing the button
 //                        toggles night mode.
 //       byte 5 = indicator output number - 1..MAX_OUT_PORTS, or 0 for none.  This
 //                selects an output port that will be turned on when night mode is
 //                activated.  Night mode activation overrides any setting made by
@@ -714,7 +764,7 @@
 // In USB messages that specify GPIO pin assignments, pins are identified by
 // 8-bit integers.  The special value 0xFF means NC (not connected).  All actual