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

/media/uploads/mjr/pinscape_no_background_small_L7Miwr6.jpg

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 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 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 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 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.

main.cpp

Committer:
mjr
Date:
2015-09-25
Revision:
29:582472d0bc57
Parent:
26:cb71c4af2912
Child:
30:6e9902f06f48

File content as of revision 29:582472d0bc57:

/* Copyright 2014 M J Roberts, MIT License
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
* and associated documentation files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or
* substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

//
// Pinscape Controller
//
// "Pinscape" is the name of my custom-built virtual pinball cabinet, so I call this
// software the Pinscape Controller.  I wrote it to handle several tasks that I needed
// for my cabinet.  It runs on a Freescale KL25Z microcontroller, which is a small and 
// inexpensive device that attaches to the cabinet PC via a USB cable, and can attach
// via custom wiring to sensors, buttons, and other devices in the cabinet.
//
// I designed the software and hardware in this project especially for my own
// cabinet, but it uses standard interfaces in Windows and Visual Pinball, so it should
// work in any VP-based cabinet, as long as you're using the usual VP software suite.  
// I've tried to document the hardware in enough detail for anyone else to duplicate 
// the entire project, and the full software is open source.
//
// The Freescale board appears to the host PC as a standard USB joystick.  This works 
// with the built-in Windows joystick device drivers, so there's no need to install any
// new drivers or other software on the PC.  Windows should recognize the Freescale
// as a joystick when you plug it into the USB port, and Windows shouldn't ask you to 
// install any drivers.  If you bring up the Windows control panel for USB Game 
// Controllers, this device will appear as "Pinscape Controller".  *Don't* do any 
// calibration with the Windows control panel or third-part calibration tools.  The 
// software calibrates the accelerometer portion automatically, and has its own special
// calibration procedure for the plunger sensor, if you're using that (see below).
//
// This software provides a whole bunch of separate features.  You can use any of these 
// features individually or all together.  If you're not using a particular feature, you
// can simply omit the extra wiring and/or hardware for that feature.  You can use
// the nudging feature by itself without any extra hardware attached, since the
// accelerometer is built in to the KL25Z board.
//
//  - Nudge sensing via the KL25Z's on-board accelerometer.  Nudging the cabinet
//    causes small accelerations that the accelerometer can detect; these are sent to
//    Visual Pinball via the joystick interface so that VP can simulate the effect
//    of the real physical nudges on its simulated ball.  VP has native handling for
//    this type of input, so all you have to do is set some preferences in VP to tell 
//    it that an accelerometer is attached.
//
//  - Plunger position sensing via an attached TAOS TSL 1410R CCD linear array sensor.  
//    To use this feature, you need to buy the TAOS device (it's not built in to the
//    KL25Z, obviously), wire it to the KL25Z (5 wire connections between the two
//    devices are required), and mount the TAOS sensor in your cabinet so that it's
//    positioned properly to capture images of the physical plunger shooter rod.
//
//    The physical mounting and wiring details are desribed in the project 
//    documentation.  
//
//    If the CCD is attached, the software constantly captures images from the CCD
//    and analyzes them to determine how far back the plunger is pulled.  It reports
//    this to Visual Pinball via the joystick interface.  This allows VP to make the
//    simulated on-screen plunger track the motion of the physical plunger in real
//    time.  As with the nudge data, VP has native handling for the plunger input, 
//    so you just need to set the VP preferences to tell it that an analog plunger 
//    device is attached.  One caveat, though: although VP itself has built-in 
//    support for an analog plunger, not all existing tables take advantage of it.  
//    Many existing tables have their own custom plunger scripting that doesn't
//    cooperate with the VP plunger input.  All tables *can* be made to work with
//    the plunger, and in most cases it only requires some simple script editing,
//    but in some cases it requires some more extensive surgery.
//
//    For best results, the plunger sensor should be calibrated.  The calibration
//    is stored in non-volatile memory on board the KL25Z, so it's only necessary
//    to do the calibration once, when you first install everything.  (You might
//    also want to re-calibrate if you physically remove and reinstall the CCD 
//    sensor or the mechanical plunger, since their alignment shift change slightly 
//    when you put everything back together.)  You can optionally install a
//    dedicated momentary switch or pushbutton to activate the calibration mode;
//    this is describe in the project documentation.  If you don't want to bother
//    with the extra button, you can also trigger calibration using the Windows 
//    setup software, which you can find on the Pinscape project page.
//
//    The calibration procedure is described in the project documentation.  Briefly,
//    when you trigger calibration mode, the software will scan the CCD for about
//    15 seconds, during which you should simply pull the physical plunger back
//    all the way, hold it for a moment, and then slowly return it to the rest
//    position.  (DON'T just release it from the retracted position, since that
//    let it shoot forward too far.  We want to measure the range from the park
//    position to the fully retracted position only.)
//
//  - Button input wiring.  24 of the KL25Z's GPIO ports are mapped as digital inputs
//    for buttons and switches.  The software reports these as joystick buttons when
//    it sends reports to the PC.  These can be used to wire physical pinball-style
//    buttons in the cabinet (e.g., flipper buttons, the Start button) and miscellaneous 
//    switches (such as a tilt bob) to the PC.  Visual Pinball can use joystick buttons
//    for input - you just have to assign a VP function to each button using VP's
//    keyboard options dialog.  To wire a button physically, connect one terminal of
//    the button switch to the KL25Z ground, and connect the other terminal to the
//    the GPIO port you wish to assign to the button.  See the buttonMap[] array
//    below for the available GPIO ports and their assigned joystick button numbers.
//    If you're not using a GPIO port, you can just leave it unconnected - the digital
//    inputs have built-in pull-up resistors, so an unconnected port is the same as
//    an open switch (an "off" state for the button).
//
//  - LedWiz emulation.  The KL25Z can appear to the PC as an LedWiz device, and will
//    accept and process LedWiz commands from the host.  The software can turn digital
//    output ports on and off, and can set varying PWM intensitiy levels on a subset
//    of ports.  (The KL25Z can only provide 6 PWM ports.  Intensity level settings on
//    other ports is ignored, so non-PWM ports can only be used for simple on/off
//    devices such as contactors and solenoids.)  The KL25Z can only supply 4mA on its
//    output ports, so external hardware is required to take advantage of the LedWiz
//    emulation.  Many different hardware designs are possible, but there's a simple
//    reference design in the documentation that uses a Darlington array IC to
//    increase the output from each port to 500mA (the same level as the LedWiz),
//    plus an extended design that adds an optocoupler and MOSFET to provide very
//    high power handling, up to about 45A or 150W, with voltages up to 100V.
//    That will handle just about any DC device directly (wtihout relays or other
//    amplifiers), and switches fast enough to support PWM devices.
//
//    The device can report any desired LedWiz unit number to the host, which makes
//    it possible to use the LedWiz emulation on a machine that also has one or more
//    actual LedWiz devices intalled.  The LedWiz design allows for up to 16 units
//    to be installed in one machine - each one is invidually addressable by its
//    distinct unit number.
//
//    The LedWiz emulation features are of course optional.  There's no need to 
//    build any of the external port hardware (or attach anything to the output 
//    ports at all) if the LedWiz features aren't needed.  Most people won't have
//    any use for the LedWiz features.  I built them mostly as a learning exercise,
//    but with a slight practical need for a handful of extra ports (I'm using the
//    cutting-edge 10-contactor setup, so my real LedWiz is full!).
//
//  - Enhanced LedWiz emulation with TLC5940 PWM controller chips.  You can attach
//    external PWM controller chips for controlling device outputs, instead of using
//    the limited LedWiz emulation through the on-board GPIO ports as described above. 
//    The software can control a set of daisy-chained TLC5940 chips, which provide
//    16 PWM outputs per chip.  Two of these chips give you the full complement
//    of 32 output ports of an actual LedWiz, and four give you 64 ports, which
//    should be plenty for nearly any virtual pinball project.
//
//
// The on-board LED on the KL25Z flashes to indicate the current device status:
//
//    two short red flashes = the device is powered but hasn't successfully
//        connected to the host via USB (either it's not physically connected
//        to the USB port, or there was a problem with the software handshake
//        with the USB device driver on the computer)
//
//    short red flash = the host computer is in sleep/suspend mode
//
//    long red/green = the LedWiz unti number has been changed, so a reset
//        is needed.  You can simply unplug the device and plug it back in,
//        or presss and hold the reset button on the device for a few seconds.
//
//    long yellow/green = everything's working, but the plunger hasn't
//        been calibrated; follow the calibration procedure described above.
//        This flash mode won't appear if the CCD has been disabled.  Note
//        that the device can't tell whether a CCD is physically attached;
//        if you don't have a CCD attached, you can set the appropriate option 
//        in config.h or use the  Windows config tool to disable the CCD 
//        software features.
//
//    alternating blue/green = everything's working
//
// Software configuration: you can change option settings by sending special
// USB commands from the PC.  I've provided a Windows program for this purpose;
// refer to the documentation for details.  For reference, here's the format
// of the USB command for option changes:
//
//    length of report = 8 bytes
//    byte 0 = 65 (0x41)
//    byte 1 = 1 (0x01)
//    byte 2 = new LedWiz unit number, 0x01 to 0x0f
//    byte 3 = feature enable bit mask:
//             0x01 = enable CCD (default = on)
//
// Plunger calibration mode: the host can activate plunger calibration mode
// by sending this packet.  This has the same effect as pressing and holding
// the plunger calibration button for two seconds, to allow activating this
// mode without attaching a physical button.
//
//    length = 8 bytes
//    byte 0 = 65 (0x41)
//    byte 1 = 2 (0x02)
//
// Exposure reports: the host can request a report of the full set of pixel
// values for the next frame by sending this special packet:
//
//    length = 8 bytes
//    byte 0 = 65 (0x41)
//    byte 1 = 3 (0x03)
//
// We'll respond with a series of special reports giving the exposure status.
// Each report has the following structure:
//
//    bytes 0:1 = 11-bit index, with high 5 bits set to 10000.  For 
//                example, 0x04 0x80 indicates index 4.  This is the 
//                starting pixel number in the report.  The first report 
//                will be 0x00 0x80 to indicate pixel #0.  
//    bytes 2:3 = 16-bit unsigned int brightness level of pixel at index
//    bytes 4:5 = brightness of pixel at index+1
//    etc for the rest of the packet
//
// This still has the form of a joystick packet at the USB level, but
// can be differentiated by the host via the status bits.  It would have
// been cleaner to use a different Report ID at the USB level, but this
// would have necessitated a different container structure in the report
// descriptor, which would have broken LedWiz compatibility.  Given that
// constraint, we have to re-use the joystick report type, making for
// this somewhat kludgey approach.
 
#include "mbed.h"
#include "math.h"
#include "USBJoystick.h"
#include "MMA8451Q.h"
#include "tsl1410r.h"
#include "FreescaleIAP.h"
#include "crc32.h"
#include "TLC5940.h"

// our local configuration file
#define DECL_EXTERNS
#include "config.h"


// ---------------------------------------------------------------------------
// utilities

// number of elements in an array
#define countof(x) (sizeof(x)/sizeof((x)[0]))

// floating point square of a number
inline float square(float x) { return x*x; }

// floating point rounding
inline float round(float x) { return x > 0 ? floor(x + 0.5) : ceil(x - 0.5); }


// ---------------------------------------------------------------------------
// USB device vendor ID, product ID, and version.  
//
// We use the vendor ID for the LedWiz, so that the PC-side software can
// identify us as capable of performing LedWiz commands.  The LedWiz uses
// a product ID value from 0xF0 to 0xFF; the last four bits identify the
// unit number (e.g., product ID 0xF7 means unit #7).  This allows multiple
// LedWiz units to be installed in a single PC; the software on the PC side
// uses the unit number to route commands to the devices attached to each
// unit.  On the real LedWiz, the unit number must be set in the firmware
// at the factory; it's not configurable by the end user.  Most LedWiz's
// ship with the unit number set to 0, but the vendor will set different
// unit numbers if requested at the time of purchase.  So if you have a
// single LedWiz already installed in your cabinet, and you didn't ask for
// a non-default unit number, your existing LedWiz will be unit 0.
//
// Note that the USB_PRODUCT_ID value set here omits the unit number.  We
// take the unit number from the saved configuration.  We provide a
// configuration command that can be sent via the USB connection to change
// the unit number, so that users can select the unit number without having
// to install a different version of the software.  We'll combine the base
// product ID here with the unit number to get the actual product ID that
// we send to the USB controller.
const uint16_t USB_VENDOR_ID = 0xFAFA;
const uint16_t USB_PRODUCT_ID = 0x00F0;
const uint16_t USB_VERSION_NO = 0x0006;


// Joystick axis report range - we report from -JOYMAX to +JOYMAX
#define JOYMAX 4096

// --------------------------------------------------------------------------
//
// Set up mappings for the joystick X and Y reports based on the mounting
// orientation of the KL25Z in the cabinet.  Visual Pinball and other 
// pinball software effectively use video coordinates to define the axes:
// positive X is to the right of the table, negative Y to the left, positive
// Y toward the front of the table, negative Y toward the back.  The KL25Z
// accelerometer is mounted on the board with positive Y toward the USB
// ports and positive X toward the right side of the board with the USB
// ports pointing up.  It's a simple matter to remap the KL25Z coordinate
// system to match VP's coordinate system for mounting orientations at
// 90-degree increments...
//
#if defined(ORIENTATION_PORTS_AT_FRONT)
# define JOY_X(x, y)   (y)
# define JOY_Y(x, y)   (x)
#elif defined(ORIENTATION_PORTS_AT_LEFT)
# define JOY_X(x, y)   (-(x))
# define JOY_Y(x, y)   (y)
#elif defined(ORIENTATION_PORTS_AT_RIGHT)
# define JOY_X(x, y)   (x)
# define JOY_Y(x, y)   (-(y))
#elif defined(ORIENTATION_PORTS_AT_REAR)
# define JOY_X(x, y)   (-(y))
# define JOY_Y(x, y)   (-(x))
#else
# error Please define one of the ORIENTATION_PORTS_AT_xxx macros to establish the accelerometer orientation in your cabinet
#endif



// --------------------------------------------------------------------------
//
// Define a symbol to tell us whether any sort of plunger sensor code
// is enabled in this build.  Note that this doesn't tell us that a
// plunger device is actually attached or *currently* enabled; it just
// tells us whether or not the code for plunger sensing is enabled in 
// the software build.  This lets us leave out some unnecessary code
// on installations where no physical plunger is attached.
//
const int PLUNGER_CODE_ENABLED =
#if defined(ENABLE_CCD_SENSOR) || defined(ENABLE_POT_SENSOR)
    1;
#else
    0;
#endif

// ---------------------------------------------------------------------------
//
// On-board RGB LED elements - we use these for diagnostic displays.
//
// Note that LED3 (the blue segment) is hard-wired on the KL25Z to PTD1,
// so PTD1 shouldn't be used for any other purpose (e.g., as a keyboard
// input or a device output).  (This is kind of unfortunate in that it's 
// one of only two ports exposed on the jumper pins that can be muxed to 
// SPI0 SCLK.  This effectively limits us to PTC5 if we want to use the 
// SPI capability.)
//
DigitalOut ledR(LED1), ledG(LED2), ledB(LED3);


// ---------------------------------------------------------------------------
//
// LedWiz emulation, and enhanced TLC5940 output controller
//
// There are two modes for this feature.  The default mode uses the on-board
// GPIO ports to implement device outputs - each LedWiz software port is
// connected to a physical GPIO pin on the KL25Z.  The KL25Z only has 10
// PWM channels, so in this mode only 10 LedWiz ports will be dimmable; the
// rest are strictly on/off.  The KL25Z also has a limited number of GPIO
// ports overall - not enough for the full complement of 32 LedWiz ports
// and 24 VP joystick inputs, so it's necessary to trade one against the
// other if both features are to be used.
//
// The alternative, enhanced mode uses external TLC5940 PWM controller
// chips to control device outputs.  In this mode, each LedWiz software
// port is mapped to an output on one of the external TLC5940 chips.
// Two 5940s is enough for the full set of 32 LedWiz ports, and we can
// support even more chips for even more outputs (although doing so requires
// breaking LedWiz compatibility, since the LedWiz USB protocol is hardwired
// for 32 outputs).  Every port in this mode has full PWM support.
//

// Figure the number of outputs.  If we're in the default LedWiz mode,
// we have a fixed set of 32 outputs.  If we're in TLC5940 enhanced mode,
// we have 16 outputs per chip.  To simplify the LedWiz compatibility code,
// always use a minimum of 32 outputs even if we have fewer than two of the
// TLC5940 chips.
#if !defined(ENABLE_TLC5940) || (TLC_NCHIPS) < 2
# define NUM_OUTPUTS   32
#else
# define NUM_OUTPUTS   ((TLC5940_NCHIPS)*16)
#endif

// Current starting output index for "PBA" messages from the PC (using
// the LedWiz USB protocol).  Each PBA message implicitly uses the
// current index as the starting point for the ports referenced in
// the message, and increases it (by 8) for the next call.
static int pbaIdx = 0;

// Generic LedWiz output port interface.  We create a cover class to 
// virtualize digital vs PWM outputs, and on-board KL25Z GPIO vs external 
// TLC5940 outputs, and give them all a common interface.  
class LwOut
{
public:
    // Set the output intensity.  'val' is 0.0 for fully off, 1.0 for
    // fully on, and fractional values for intermediate intensities.
    virtual void set(float val) = 0;
};


#ifdef ENABLE_TLC5940

// The TLC5940 interface object.
TLC5940 tlc5940(TLC5940_SCLK, TLC5940_SIN, TLC5940_GSCLK, TLC5940_BLANK,
    TLC5940_XLAT, TLC5940_NCHIPS);

// LwOut class for TLC5940 outputs.  These are fully PWM capable.
// The 'idx' value in the constructor is the output index in the
// daisy-chained TLC5940 array.  0 is output #0 on the first chip,
// 1 is #1 on the first chip, 15 is #15 on the first chip, 16 is
// #0 on the second chip, 32 is #0 on the third chip, etc.
class Lw5940Out: public LwOut
{
public:
    Lw5940Out(int idx) : idx(idx) { prv = -1; }
    virtual void set(float val)
    {
        if (val != prv)
           tlc5940.set(idx, (int)(val * 4095));
    }
    int idx;
    float prv;
};

#else // ENABLE_TLC5940

// 
// Default LedWiz mode - using on-board GPIO ports.  In this mode, we
// assign a KL25Z GPIO port to each LedWiz output.  We have to use a
// mix of PWM-capable and Digital-Only ports in this configuration, 
// since the KL25Z hardware only has 10 PWM channels, which isn't
// enough to fill out the full complement of 32 LedWiz outputs.
//

// LwOut class for a PWM-capable GPIO port
class LwPwmOut: public LwOut
{
public:
    LwPwmOut(PinName pin) : p(pin) { prv = -1; }
    virtual void set(float val) 
    { 
        if (val != prv)
            p.write(prv = val); 
    }
    PwmOut p;
    float prv;
};

// LwOut class for a Digital-Only (Non-PWM) GPIO port
class LwDigOut: public LwOut
{
public:
    LwDigOut(PinName pin) : p(pin) { prv = -1; }
    virtual void set(float val) 
    {
         if (val != prv)
            p.write((prv = val) == 0.0 ? 0 : 1); 
    }
    DigitalOut p;
    float prv;
};

#endif // ENABLE_TLC5940

// LwOut class for unmapped ports.  The LedWiz protocol is hardwired
// for 32 ports, but we might not want to assign all 32 software ports
// to physical output pins - the KL25Z has a limited number of GPIO
// ports, so we might not have enough available GPIOs to fill out the
// full LedWiz complement after assigning GPIOs for other functions.
// This class is used to populate the LedWiz mapping array for ports
// that aren't connected to physical outputs; it simply ignores value 
// changes.
class LwUnusedOut: public LwOut
{
public:
    LwUnusedOut() { }
    virtual void set(float val) { }
};

// Array of output physical pin assignments.  This array is indexed
// by LedWiz logical port number - lwPin[n] is the maping for LedWiz
// port n (0-based).  If we're using GPIO ports to implement outputs,
// we initialize the array at start-up to map each logical port to the 
// physical GPIO pin for the port specified in the ledWizPortMap[] 
// array in config.h.  If we're using TLC5940 chips for the outputs,
// we map each logical port to the corresponding TLC5940 output.
static LwOut *lwPin[NUM_OUTPUTS];

// initialize the output pin array
void initLwOut()
{
    for (int i = 0 ; i < countof(lwPin) ; ++i)
    {
#ifdef ENABLE_TLC5940
        // Set up a TLC5940 output.  If the output is within range of
        // the connected number of chips (16 outputs per chip), assign it
        // to the current index, otherwise leave it unattached.
        if (i < (TLC5940_NCHIPS)*16)
            lwPin[i] = new Lw5940Out(i);
        else
            lwPin[i] = new LwUnusedOut();

#else // ENABLE_TLC5940
        // Set up the GPIO pin.  If the pin is not connected ("NC" in the
        // pin map), set up a dummy "unused" output for it.  If it's a
        // real pin, set up a PWM-capable or Digital-Only output handler
        // object, according to the pin type in the map.
        PinName p = (i < countof(ledWizPortMap) ? ledWizPortMap[i].pin : NC);
        if (p == NC)
            lwPin[i] = new LwUnusedOut();
        else if (ledWizPortMap[i].isPWM)
            lwPin[i] = new LwPwmOut(p);
        else
            lwPin[i] = new LwDigOut(p);
            
#endif // ENABLE_TLC5940

    }
}

// Current absolute brightness level for an output.  This is a float
// value from 0.0 for fully off to 1.0 for fully on.  This is the final
// derived value for the port.  For outputs set by LedWiz messages, 
// this is derived from te LedWiz state, and is updated on each pulse 
// timer interrupt for lights in flashing states.  For outputs set by 
// extended protocol messages, this is simply the brightness last set.
static float outLevel[NUM_OUTPUTS];

// LedWiz output states.
//
// The LedWiz protocol has two separate control axes for each output.
// One axis is its on/off state; the other is its "profile" state, which
// is either a fixed brightness or a blinking pattern for the light.
// The two axes are independent.
//
// Note that the LedWiz protocol can only address 32 outputs, so the
// wizOn and wizVal arrays have fixed sizes of 32 elements no matter
// how many physical outputs we're using.

// on/off state for each LedWiz output
static uint8_t wizOn[32];

// Profile (brightness/blink) state for each LedWiz output.  If the
// output was last updated through an LedWiz protocol message, it
// will have one of these values:
//
//   0-48 = fixed brightness 0% to 100%
//   129 = ramp up / ramp down
//   130 = flash on / off
//   131 = on / ramp down
//   132 = ramp up / on
//
// Special value 255:  If the output was updated through the 
// extended protocol, we'll set the wizVal entry to 255, which has 
// no meaning in the LedWiz protocol.  This tells us that the value 
// in outLevel[] was set directly from the extended protocol, so it 
// shouldn't be derived from wizVal[].
//
static uint8_t wizVal[32] = {
    48, 48, 48, 48, 48, 48, 48, 48,
    48, 48, 48, 48, 48, 48, 48, 48,
    48, 48, 48, 48, 48, 48, 48, 48,
    48, 48, 48, 48, 48, 48, 48, 48
};

// LedWiz flash speed.  This is a value from 1 to 7 giving the pulse
// rate for lights in blinking states.
static uint8_t wizSpeed = 2;

// Current LedWiz flash cycle counter.
static uint8_t wizFlashCounter = 0;

// Get the current brightness level for an LedWiz output.
static float wizState(int idx)
{
    // if the output was last set with an extended protocol message,
    // use the value set there, ignoring the output's LedWiz state
    if (wizVal[idx] == 255)
        return outLevel[idx];
    
    // if it's off, show at zero intensity
    if (!wizOn[idx])
        return 0;

    // check the state
    uint8_t val = wizVal[idx];
    if (val <= 48)
    {
        // PWM brightness/intensity level.  Rescale from the LedWiz
        // 0..48 integer range to our internal PwmOut 0..1 float range.
        // Note that on the actual LedWiz, level 48 is actually about
        // 98% on - contrary to the LedWiz documentation, level 49 is 
        // the true 100% level.  (In the documentation, level 49 is
        // simply not a valid setting.)  Even so, we treat level 48 as
        // 100% on to match the documentation.  This won't be perfectly
        // ocmpatible with the actual LedWiz, but it makes for such a
        // small difference in brightness (if the output device is an
        // LED, say) that no one should notice.  It seems better to
        // err in this direction, because while the difference in
        // brightness when attached to an LED won't be noticeable, the
        // difference in duty cycle when attached to something like a
        // contactor *can* be noticeable - anything less than 100%
        // can cause a contactor or relay to chatter.  There's almost
        // never a situation where you'd want values other than 0% and
        // 100% for a contactor or relay, so treating level 48 as 100%
        // makes us work properly with software that's expecting the
        // documented LedWiz behavior and therefore uses level 48 to
        // turn a contactor or relay fully on.
        return val/48.0;
    }
    else if (val == 49)
    {
        // 49 is undefined in the LedWiz documentation, but actually
        // means 100% on.  The documentation says that levels 1-48 are
        // the full PWM range, but empirically it appears that the real
        // range implemented in the firmware is 1-49.  Some software on
        // the PC side (notably DOF) is aware of this and uses level 49
        // to mean "100% on".  To ensure compatibility with existing 
        // PC-side software, we need to recognize level 49.
        return 1.0;
    }
    else if (val == 129)
    {
        //   129 = ramp up / ramp down
        if (wizFlashCounter < 128)
            return wizFlashCounter/127.0;
        else
            return (255 - wizFlashCounter)/127.0;
    }
    else if (val == 130)
    {
        //   130 = flash on / off
        return (wizFlashCounter < 128 ? 1.0 : 0.0);
    }
    else if (val == 131)
    {
        //   131 = on / ramp down
        return (255 - wizFlashCounter)/255.0;
    }
    else if (val == 132)
    {
        //   132 = ramp up / on
        return wizFlashCounter/255.0;
    }
    else
    {
        // Other values are undefined in the LedWiz documentation.  Hosts
        // *should* never send undefined values, since whatever behavior an
        // LedWiz unit exhibits in response is accidental and could change
        // in a future version.  We'll treat all undefined values as equivalent 
        // to 48 (fully on).
        return 1.0;
    }
}

// LedWiz flash timer pulse.  This fires periodically to update 
// LedWiz flashing outputs.  At the slowest pulse speed set via
// the SBA command, each waveform cycle has 256 steps, so we
// choose the pulse time base so that the slowest cycle completes
// in 2 seconds.  This seems to roughly match the real LedWiz
// behavior.  We run the pulse timer at the same rate regardless
// of the pulse speed; at higher pulse speeds, we simply use
// larger steps through the cycle on each interrupt.  Running
// every 1/127 of a second = 8ms seems to be a pretty light load.
Timeout wizPulseTimer;
#define WIZ_PULSE_TIME_BASE  (1.0/127.0)
static void wizPulse()
{
    // increase the counter by the speed increment, and wrap at 256
    wizFlashCounter += wizSpeed;
    wizFlashCounter &= 0xff;
    
    // if we have any flashing lights, update them
    int ena = false;
    for (int i = 0 ; i < 32 ; ++i)
    {
        if (wizOn[i])
        {
            uint8_t s = wizVal[i];
            if (s >= 129 && s <= 132)
            {
                lwPin[i]->set(wizState(i));
                ena = true;
            }
        }
    }    

    // Set up the next timer pulse only if we found anything flashing.
    // To minimize overhead from this feature, we only enable the interrupt
    // when we need it.  This eliminates any performance penalty to other
    // features when the host software doesn't care about the flashing 
    // modes.  For example, DOF never uses these modes, so there's no 
    // need for them when running Visual Pinball.
    if (ena)
        wizPulseTimer.attach(wizPulse, WIZ_PULSE_TIME_BASE);
}

// Update the physical outputs connected to the LedWiz ports.  This is 
// called after any update from an LedWiz protocol message.
static void updateWizOuts()
{
    // update each output
    int pulse = false;
    for (int i = 0 ; i < 32 ; ++i)
    {
        pulse |= (wizVal[i] >= 129 && wizVal[i] <= 132);
        lwPin[i]->set(wizState(i));
    }
    
    // if any outputs are set to flashing mode, and the pulse timer
    // isn't running, turn it on
    if (pulse)
        wizPulseTimer.attach(wizPulse, WIZ_PULSE_TIME_BASE);
}

// ---------------------------------------------------------------------------
//
// Button input
//

// button input map array
DigitalIn *buttonDigIn[32];

// button state
struct ButtonState
{
    // current on/off state
    int pressed;
    
    // Sticky time remaining for current state.  When a
    // state transition occurs, we set this to a debounce
    // period.  Future state transitions will be ignored
    // until the debounce time elapses.
    int t;
} buttonState[32];

// timer for button reports
static Timer buttonTimer;

// initialize the button inputs
void initButtons()
{
    // create the digital inputs
    for (int i = 0 ; i < countof(buttonDigIn) ; ++i)
    {
        if (i < countof(buttonMap) && buttonMap[i] != NC)
            buttonDigIn[i] = new DigitalIn(buttonMap[i]);
        else
            buttonDigIn[i] = 0;
    }
    
    // start the button timer
    buttonTimer.start();
}


// read the button input state
uint32_t readButtons()
{
    // start with all buttons off
    uint32_t buttons = 0;
    
    // figure the time elapsed since the last scan
    int dt = buttonTimer.read_ms();
    
    // reset the timef for the next scan
    buttonTimer.reset();
    
    // scan the button list
    uint32_t bit = 1;
    DigitalIn **di = buttonDigIn;
    ButtonState *bs = buttonState;
    for (int i = 0 ; i < countof(buttonDigIn) ; ++i, ++di, ++bs, bit <<= 1)
    {
        // read this button
        if (*di != 0)
        {
            // deduct the elapsed time since the last update
            // from the button's remaining sticky time
            bs->t -= dt;
            if (bs->t < 0)
                bs->t = 0;
            
            // If the sticky time has elapsed, note the new physical
            // state of the button.  If we still have sticky time
            // remaining, ignore the physical state; the last state
            // change persists until the sticky time elapses so that
            // we smooth out any "bounce" (electrical transients that
            // occur when the switch contact is opened or closed).
            if (bs->t == 0)
            {
                // get the new physical state
                int pressed = !(*di)->read();
                
                // update the button's logical state if this is a change
                if (pressed != bs->pressed)
                {
                    // store the new state
                    bs->pressed = pressed;
                    
                    // start a new sticky period for debouncing this
                    // state change
                    bs->t = 25;
                }
            }
            
            // if it's pressed, OR its bit into the state
            if (bs->pressed)
                buttons |= bit;
        }
    }
    
    // return the new button list
    return buttons;
}

// ---------------------------------------------------------------------------
//
// Customization joystick subbclass
//

class MyUSBJoystick: public USBJoystick
{
public:
    MyUSBJoystick(uint16_t vendor_id, uint16_t product_id, uint16_t product_release) 
        : USBJoystick(vendor_id, product_id, product_release, true)
    {
        suspended_ = false;
    }
    
    // are we connected?
    int isConnected()  { return configured(); }
    
    // Are we in suspend mode?
    int isSuspended() const { return suspended_; }
    
protected:
    virtual void suspendStateChanged(unsigned int suspended)
        { suspended_ = suspended; }

    // are we suspended?
    int suspended_; 
};

// ---------------------------------------------------------------------------
// 
// Accelerometer (MMA8451Q)
//

// The MMA8451Q is the KL25Z's on-board 3-axis accelerometer.
//
// This is a custom wrapper for the library code to interface to the
// MMA8451Q.  This class encapsulates an interrupt handler and 
// automatic calibration.
//
// We install an interrupt handler on the accelerometer "data ready" 
// interrupt to ensure that we fetch each sample immediately when it
// becomes available.  The accelerometer data rate is fiarly high
// (800 Hz), so it's not practical to keep up with it by polling.
// Using an interrupt handler lets us respond quickly and read
// every sample.
//
// We automatically calibrate the accelerometer so that it's not
// necessary to get it exactly level when installing it, and so
// that it's also not necessary to calibrate it manually.  There's
// lots of experience that tells us that manual calibration is a
// terrible solution, mostly because cabinets tend to shift slightly
// during use, requiring frequent recalibration.  Instead, we
// calibrate automatically.  We continuously monitor the acceleration
// data, watching for periods of constant (or nearly constant) values.
// Any time it appears that the machine has been at rest for a while
// (about 5 seconds), we'll average the readings during that rest
// period and use the result as the level rest position.  This is
// is ongoing, so we'll quickly find the center point again if the 
// machine is moved during play (by an especially aggressive bout
// of nudging, say).
//

// I2C address of the accelerometer (this is a constant of the KL25Z)
const int MMA8451_I2C_ADDRESS = (0x1d<<1);

// SCL and SDA pins for the accelerometer (constant for the KL25Z)
#define MMA8451_SCL_PIN   PTE25
#define MMA8451_SDA_PIN   PTE24

// Digital in pin to use for the accelerometer interrupt.  For the KL25Z,
// this can be either PTA14 or PTA15, since those are the pins physically
// wired on this board to the MMA8451 interrupt controller.
#define MMA8451_INT_PIN   PTA15


// accelerometer input history item, for gathering calibration data
struct AccHist
{
    AccHist() { x = y = d = 0.0; xtot = ytot = 0.0; cnt = 0; }
    void set(float x, float y, AccHist *prv)
    {
        // save the raw position
        this->x = x;
        this->y = y;
        this->d = distance(prv);
    }
    
    // reading for this entry
    float x, y;
    
    // distance from previous entry
    float d;
    
    // total and count of samples averaged over this period
    float xtot, ytot;
    int cnt;

    void clearAvg() { xtot = ytot = 0.0; cnt = 0; }    
    void addAvg(float x, float y) { xtot += x; ytot += y; ++cnt; }
    float xAvg() const { return xtot/cnt; }
    float yAvg() const { return ytot/cnt; }
    
    float distance(AccHist *p)
        { return sqrt(square(p->x - x) + square(p->y - y)); }
};

// accelerometer wrapper class
class Accel
{
public:
    Accel(PinName sda, PinName scl, int i2cAddr, PinName irqPin)
        : mma_(sda, scl, i2cAddr), intIn_(irqPin)
    {
        // remember the interrupt pin assignment
        irqPin_ = irqPin;

        // reset and initialize
        reset();
    }
    
    void reset()
    {
        // clear the center point
        cx_ = cy_ = 0.0;
        
        // start the calibration timer
        tCenter_.start();
        iAccPrv_ = nAccPrv_ = 0;
        
        // reset and initialize the MMA8451Q
        mma_.init();
                
        // set the initial integrated velocity reading to zero
        vx_ = vy_ = 0;
        
        // set up our accelerometer interrupt handling
        intIn_.rise(this, &Accel::isr);
        mma_.setInterruptMode(irqPin_ == PTA14 ? 1 : 2);
        
        // read the current registers to clear the data ready flag
        mma_.getAccXYZ(ax_, ay_, az_);

        // start our timers
        tGet_.start();
        tInt_.start();
    }
    
    void get(int &x, int &y) 
    {
         // disable interrupts while manipulating the shared data
         __disable_irq();
         
         // read the shared data and store locally for calculations
         float ax = ax_, ay = ay_;
         float vx = vx_, vy = vy_;
         
         // reset the velocity sum for the next run
         vx_ = vy_ = 0;

         // get the time since the last get() sample
         float dt = tGet_.read_us()/1.0e6;
         tGet_.reset();
         
         // done manipulating the shared data
         __enable_irq();
         
         // adjust the readings for the integration time
         vx /= dt;
         vy /= dt;
         
         // add this sample to the current calibration interval's running total
         AccHist *p = accPrv_ + iAccPrv_;
         p->addAvg(ax, ay);

         // check for auto-centering every so often
         if (tCenter_.read_ms() > 1000)
         {
             // add the latest raw sample to the history list
             AccHist *prv = p;
             iAccPrv_ = (iAccPrv_ + 1) % maxAccPrv;
             p = accPrv_ + iAccPrv_;
             p->set(ax, ay, prv);

             // if we have a full complement, check for stability
             if (nAccPrv_ >= maxAccPrv)
             {
                 // check if we've been stable for all recent samples
                 static const float accTol = .01;
                 AccHist *p0 = accPrv_;
                 if (p0[0].d < accTol
                     && p0[1].d < accTol
                     && p0[2].d < accTol
                     && p0[3].d < accTol
                     && p0[4].d < accTol)
                 {
                     // Figure the new calibration point as the average of
                     // the samples over the rest period
                     cx_ = (p0[0].xAvg() + p0[1].xAvg() + p0[2].xAvg() + p0[3].xAvg() + p0[4].xAvg())/5.0;
                     cy_ = (p0[0].yAvg() + p0[1].yAvg() + p0[2].yAvg() + p0[3].yAvg() + p0[4].yAvg())/5.0;
                 }
             }
             else
             {
                // not enough samples yet; just up the count
                ++nAccPrv_;
             }
             
             // clear the new item's running totals
             p->clearAvg();
            
             // reset the timer
             tCenter_.reset();
         }
         
         // report our integrated velocity reading in x,y
         x = rawToReport(vx);
         y = rawToReport(vy);
         
#ifdef DEBUG_PRINTF
         if (x != 0 || y != 0)        
             printf("%f %f %d %d %f\r\n", vx, vy, x, y, dt);
#endif
     }    
         
private:
    // adjust a raw acceleration figure to a usb report value
    int rawToReport(float v)
    {
        // scale to the joystick report range and round to integer
        int i = int(round(v*JOYMAX));
        
        // if it's near the center, scale it roughly as 20*(i/20)^2,
        // to suppress noise near the rest position
        static const int filter[] = { 
            -18, -16, -14, -13, -11, -10, -8, -7, -6, -5, -4, -3, -2, -2, -1, -1, 0, 0, 0, 0,
            0,
            0, 0, 0, 0, 1, 1, 2, 2, 3, 4, 5, 6, 7, 8, 10, 11, 13, 14, 16, 18
        };
        return (i > 20 || i < -20 ? i : filter[i+20]);
    }

    // interrupt handler
    void isr()
    {
        // Read the axes.  Note that we have to read all three axes
        // (even though we only really use x and y) in order to clear
        // the "data ready" status bit in the accelerometer.  The
        // interrupt only occurs when the "ready" bit transitions from
        // off to on, so we have to make sure it's off.
        float x, y, z;
        mma_.getAccXYZ(x, y, z);
        
        // calculate the time since the last interrupt
        float dt = tInt_.read_us()/1.0e6;
        tInt_.reset();

        // integrate the time slice from the previous reading to this reading
        vx_ += (x + ax_ - 2*cx_)*dt/2;
        vy_ += (y + ay_ - 2*cy_)*dt/2;
        
        // store the updates
        ax_ = x;
        ay_ = y;
        az_ = z;
    }
    
    // underlying accelerometer object
    MMA8451Q mma_;
    
    // last raw acceleration readings
    float ax_, ay_, az_;
    
    // integrated velocity reading since last get()
    float vx_, vy_;
        
    // timer for measuring time between get() samples
    Timer tGet_;
    
    // timer for measuring time between interrupts
    Timer tInt_;

    // Calibration reference point for accelerometer.  This is the
    // average reading on the accelerometer when in the neutral position
    // at rest.
    float cx_, cy_;

    // timer for atuo-centering
    Timer tCenter_;

    // Auto-centering history.  This is a separate history list that
    // records results spaced out sparesely over time, so that we can
    // watch for long-lasting periods of rest.  When we observe nearly
    // no motion for an extended period (on the order of 5 seconds), we
    // take this to mean that the cabinet is at rest in its neutral 
    // position, so we take this as the calibration zero point for the
    // accelerometer.  We update this history continuously, which allows
    // us to continuously re-calibrate the accelerometer.  This ensures
    // that we'll automatically adjust to any actual changes in the
    // cabinet's orientation (e.g., if it gets moved slightly by an
    // especially strong nudge) as well as any systematic drift in the
    // accelerometer measurement bias (e.g., from temperature changes).
    int iAccPrv_, nAccPrv_;
    static const int maxAccPrv = 5;
    AccHist accPrv_[maxAccPrv];
    
    // interurupt pin name
    PinName irqPin_;
    
    // interrupt router
    InterruptIn intIn_;
};


// ---------------------------------------------------------------------------
//
// Clear the I2C bus for the MMA8451Q.  This seems necessary some of the time
// for reasons that aren't clear to me.  Doing a hard power cycle has the same
// effect, but when we do a soft reset, the hardware sometimes seems to leave
// the MMA's SDA line stuck low.  Forcing a series of 9 clock pulses through
// the SCL line is supposed to clear this condition.  I'm not convinced this
// actually works with the way this component is wired on the KL25Z, but it
// seems harmless, so we'll do it on reset in case it does some good.  What
// we really seem to need is a way to power cycle the MMA8451Q if it ever 
// gets stuck, but this is simply not possible in software on the KL25Z. 
// 
// If the accelerometer does get stuck, and a software reboot doesn't reset
// it, the only workaround is to manually power cycle the whole KL25Z by 
// unplugging both of its USB connections.
//
void clear_i2c()
{
    // assume a general-purpose output pin to the I2C clock
    DigitalOut scl(MMA8451_SCL_PIN);
    DigitalIn sda(MMA8451_SDA_PIN);
    
    // clock the SCL 9 times
    for (int i = 0 ; i < 9 ; ++i)
    {
        scl = 1;
        wait_us(20);
        scl = 0;
        wait_us(20);
    }
}
 
// ---------------------------------------------------------------------------
//
// Include the appropriate plunger sensor definition.  This will define a
// class called PlungerSensor, with a standard interface that we use in
// the main loop below.  This is *kind of* like a virtual class interface,
// but it actually defines the methods statically, which is a little more
// efficient at run-time.  There's no need for a true virtual interface
// because we don't need to be able to change sensor types on the fly.
//

#if defined(ENABLE_CCD_SENSOR)
#include "ccdSensor.h"
#elif defined(ENABLE_POT_SENSOR)
#include "potSensor.h"
#else
#include "nullSensor.h"
#endif


// ---------------------------------------------------------------------------
//
// Non-volatile memory (NVM)
//

// Structure defining our NVM storage layout.  We store a small
// amount of persistent data in flash memory to retain calibration
// data when powered off.
struct NVM
{
    // checksum - we use this to determine if the flash record
    // has been properly initialized
    uint32_t checksum;

    // signature value
    static const uint32_t SIGNATURE = 0x4D4A522A;
    static const uint16_t VERSION = 0x0003;
    
    // Is the data structure valid?  We test the signature and 
    // checksum to determine if we've been properly stored.
    int valid() const
    {
        return (d.sig == SIGNATURE 
                && d.vsn == VERSION
                && d.sz == sizeof(NVM)
                && checksum == CRC32(&d, sizeof(d)));
    }
    
    // save to non-volatile memory
    void save(FreescaleIAP &iap, int addr)
    {
        // update the checksum and structure size
        checksum = CRC32(&d, sizeof(d));
        d.sz = sizeof(NVM);
        
        // erase the sector
        iap.erase_sector(addr);

        // save the data
        iap.program_flash(addr, this, sizeof(*this));
    }
    
    // reset calibration data for calibration mode
    void resetPlunger()
    {
        // set extremes for the calibration data
        d.plungerMax = 0;
        d.plungerZero = npix;
        d.plungerMin = npix;
    }
    
    // stored data (excluding the checksum)
    struct
    {
        // Signature, structure version, and structure size - further verification 
        // that we have valid initialized data.  The size is a simple proxy for a
        // structure version, as the most common type of change to the structure as
        // the software evolves will be the addition of new elements.  We also
        // provide an explicit version number that we can update manually if we
        // make any changes that don't affect the structure size but would affect
        // compatibility with a saved record (e.g., swapping two existing elements).
        uint32_t sig;
        uint16_t vsn;
        int sz;
        
        // has the plunger been manually calibrated?
        int plungerCal;
        
        // Plunger calibration min, zero, and max.  The zero point is the 
        // rest position (aka park position), where it's in equilibrium between 
        // the main spring and the barrel spring.  It can travel a small distance
        // forward of the rest position, because the barrel spring can be
        // compressed by the user pushing on the plunger or by the momentum
        // of a release motion.  The minimum is the maximum forward point where
        // the barrel spring can't be compressed any further.
        int plungerMin;
        int plungerZero;
        int plungerMax;
        
        // is the plunger sensor enabled?
        int plungerEnabled;
        
        // LedWiz unit number
        uint8_t ledWizUnitNo;
    } d;
};


// ---------------------------------------------------------------------------
//
// Main program loop.  This is invoked on startup and runs forever.  Our
// main work is to read our devices (the accelerometer and the CCD), process
// the readings into nudge and plunger position data, and send the results
// to the host computer via the USB joystick interface.  We also monitor
// the USB connection for incoming LedWiz commands and process those into
// port outputs.
//
int main(void)
{
    // turn off our on-board indicator LED
    ledR = 1;
    ledG = 1;
    ledB = 1;
    
    // initialize the LedWiz ports
    initLwOut();
    
    // initialize the button input ports
    initButtons();
    
    // we don't need a reset yet
    bool needReset = false;
    
    // clear the I2C bus for the accelerometer
    clear_i2c();
    
    // set up a flash memory controller
    FreescaleIAP iap;
    
    // use the last sector of flash for our non-volatile memory structure
    int flash_addr = (iap.flash_size() - SECTOR_SIZE);
    NVM *flash = (NVM *)flash_addr;
    NVM cfg;
    
    // check for valid flash
    bool flash_valid = flash->valid();
                      
    // if the flash is valid, load it; otherwise initialize to defaults
    if (flash_valid) {
        memcpy(&cfg, flash, sizeof(cfg));
        printf("Flash restored: plunger cal=%d, min=%d, zero=%d, max=%d\r\n", 
            cfg.d.plungerCal, cfg.d.plungerMin, cfg.d.plungerZero, cfg.d.plungerMax);
    }
    else {
        printf("Factory reset\r\n");
        cfg.d.sig = cfg.SIGNATURE;
        cfg.d.vsn = cfg.VERSION;
        cfg.d.plungerCal = 0;
        cfg.d.plungerMin = 0;        // assume we can go all the way forward...
        cfg.d.plungerMax = npix;     // ...and all the way back
        cfg.d.plungerZero = npix/6;  // the rest position is usually around 1/2" back
        cfg.d.ledWizUnitNo = DEFAULT_LEDWIZ_UNIT_NUMBER - 1;  // unit numbering starts from 0 internally
        cfg.d.plungerEnabled = PLUNGER_CODE_ENABLED;
    }
    
    // Create the joystick USB client.  Note that we use the LedWiz unit
    // number from the saved configuration.
    MyUSBJoystick js(
        USB_VENDOR_ID, 
        USB_PRODUCT_ID | cfg.d.ledWizUnitNo,
        USB_VERSION_NO);
        
    // last report timer - we use this to throttle reports, since VP
    // doesn't want to hear from us more than about every 10ms
    Timer reportTimer;
    reportTimer.start();

    // initialize the calibration buttons, if present
    DigitalIn *calBtn = (CAL_BUTTON_PIN == NC ? 0 : new DigitalIn(CAL_BUTTON_PIN));
    DigitalOut *calBtnLed = (CAL_BUTTON_LED == NC ? 0 : new DigitalOut(CAL_BUTTON_LED));

    // plunger calibration button debounce timer
    Timer calBtnTimer;
    calBtnTimer.start();
    int calBtnLit = false;
    
    // Calibration button state:
    //  0 = not pushed
    //  1 = pushed, not yet debounced
    //  2 = pushed, debounced, waiting for hold time
    //  3 = pushed, hold time completed - in calibration mode
    int calBtnState = 0;
    
    // set up a timer for our heartbeat indicator
    Timer hbTimer;
    hbTimer.start();
    int hb = 0;
    uint16_t hbcnt = 0;
    
    // set a timer for accelerometer auto-centering
    Timer acTimer;
    acTimer.start();
    
    // create the accelerometer object
    Accel accel(MMA8451_SCL_PIN, MMA8451_SDA_PIN, MMA8451_I2C_ADDRESS, MMA8451_INT_PIN);
    
#ifdef ENABLE_JOYSTICK
    // last accelerometer report, in joystick units (we report the nudge
    // acceleration via the joystick x & y axes, per the VP convention)
    int x = 0, y = 0;
    
    // flag: send a pixel dump after the next read
    bool reportPix = false;
#endif

#ifdef ENABLE_TLC5940
    // start the TLC5940 clock
    tlc5940.start();
#endif

    // create our plunger sensor object
    PlungerSensor plungerSensor;

    // last plunger report position, in 'npix' normalized pixel units
    int pos = 0;
    
    // last plunger report, in joystick units (we report the plunger as the
    // "z" axis of the joystick, per the VP convention)
    int z = 0;
    
    // most recent prior plunger readings, for tracking release events(z0 is
    // reading just before the last one we reported, z1 is the one before that, 
    // z2 the next before that)
    int z0 = 0, z1 = 0, z2 = 0;
    
    // Simulated "bounce" position when firing.  We model the bounce off of
    // the barrel spring when the plunger is released as proportional to the
    // distance it was retracted just before being released.
    int zBounce = 0;
    
    // Simulated Launch Ball button state.  If a "ZB Launch Ball" port is
    // defined for our LedWiz port mapping, any time that port is turned ON,
    // we'll simulate pushing the Launch Ball button if the player pulls 
    // back and releases the plunger, or simply pushes on the plunger from
    // the rest position.  This allows the plunger to be used in lieu of a
    // physical Launch Ball button for tables that don't have plungers.
    //
    // States:
    //   0 = default
    //   1 = cocked (plunger has been pulled back about 1" from state 0)
    //   2 = uncocked (plunger is pulled back less than 1" from state 1)
    //   3 = launching, plunger is forward beyond park position
    //   4 = launching, plunger is behind park position
    //   5 = pressed and holding (plunger has been pressed forward beyond 
    //       the park position from state 0)
    int lbState = 0;
    
    // Time since last lbState transition.  Some of the states are time-
    // sensitive.  In the "uncocked" state, we'll return to state 0 if
    // we remain in this state for more than a few milliseconds, since
    // it indicates that the plunger is being slowly returned to rest
    // rather than released.  In the "launching" state, we need to release 
    // the Launch Ball button after a moment, and we need to wait for 
    // the plunger to come to rest before returning to state 0.
    Timer lbTimer;
    lbTimer.start();
    
    // Launch Ball simulated push timer.  We start this when we simulate
    // the button push, and turn off the simulated button when enough time
    // has elapsed.
    Timer lbBtnTimer;
    
    // Simulated button states.  This is a vector of button states
    // for the simulated buttons.  We combine this with the physical
    // button states on each USB joystick report, so we will report
    // a button as pressed if either the physical button is being pressed
    // or we're simulating a press on the button.  This is used for the
    // simulated Launch Ball button.
    uint32_t simButtons = 0;
    
    // Firing in progress: we set this when we detect the start of rapid 
    // plunger movement from a retracted position towards the rest position.
    //
    // When we detect a firing event, we send VP a series of synthetic
    // reports simulating the idealized plunger motion.  The actual physical
    // motion is much too fast to report to VP; in the time between two USB
    // reports, the plunger can shoot all the way forward, rebound off of
    // the barrel spring, bounce back part way, and bounce forward again,
    // or even do all of this more than once.  This means that sampling the 
    // physical motion at the USB report rate would create a misleading 
    // picture of the plunger motion, since our samples would catch the 
    // plunger at random points in this oscillating motion.  From the 
    // user's perspective, the physical action that occurred is simply that 
    // the plunger was released from a particular distance, so it's this 
    // high-level event that we want to convey to VP.  To do this, we
    // synthesize a series of reports to convey an idealized version of
    // the release motion that's perfectly synchronized to the VP reports.  
    // Essentially we pretend that our USB position samples are exactly 
    // aligned in time with (1) the point of retraction just before the 
    // user released the plunger, (2) the point of maximum forward motion 
    // just after the user released the plunger (the point of maximum 
    // compression as the plunger bounces off of the barrel spring), and 
    // (3) the plunger coming to rest at the park position.  This series
    // of reports is synthetic in the sense that it's not what we actually
    // see on the CCD at the times of these reports - the true plunger
    // position is oscillating at high speed during this period.  But at
    // the same time it conveys a more faithful picture of the true physical
    // motion to VP, and allows VP to reproduce the true physical motion 
    // more faithfully in its simulation model, by correcting for the
    // relatively low sampling rate in the communication path between the
    // real plunger and VP's model plunger.
    //
    // If 'firing' is non-zero, it's the index of our current report in
    // the synthetic firing report series.
    int firing = 0;

    // start the first CCD integration cycle
    plungerSensor.init();
    
    // Device status.  We report this on each update so that the host config
    // tool can detect our current settings.  This is a bit mask consisting
    // of these bits:
    //    0x01  -> plunger sensor enabled
    uint16_t statusFlags = (cfg.d.plungerEnabled ? 0x01 : 0x00);
    
    // we're all set up - now just loop, processing sensor reports and 
    // host requests
    for (;;)
    {
        // Look for an incoming report.  Process a few input reports in
        // a row, but stop after a few so that a barrage of inputs won't
        // starve our output event processing.  Also, pause briefly between
        // reads; allowing reads to occur back-to-back seems to occasionally 
        // stall the USB pipeline (for reasons unknown; I'd fix the underlying 
        // problem if I knew what it was).
        HID_REPORT report;
        for (int rr = 0 ; rr < 4 && js.readNB(&report) ; ++rr, wait_ms(1))
        {
            // all Led-Wiz reports are 8 bytes exactly
            if (report.length == 8)
            {
                uint8_t *data = report.data;
                if (data[0] == 64) 
                {
                    // LWZ-SBA - first four bytes are bit-packed on/off flags
                    // for the outputs; 5th byte is the pulse speed (1-7)
                    //printf("LWZ-SBA %02x %02x %02x %02x ; %02x\r\n",
                    //       data[1], data[2], data[3], data[4], data[5]);
    
                    // update all on/off states
                    for (int i = 0, bit = 1, ri = 1 ; i < 32 ; ++i, bit <<= 1)
                    {
                        if (bit == 0x100) {
                            bit = 1;
                            ++ri;
                        }
                        wizOn[i] = ((data[ri] & bit) != 0);
                    }
                    
                    // set the flash speed - enforce the value range 1-7
                    wizSpeed = data[5];
                    if (wizSpeed < 1)
                        wizSpeed = 1;
                    else if (wizSpeed > 7)
                        wizSpeed = 7;
        
                    // update the physical outputs
                    updateWizOuts();
                    
                    // reset the PBA counter
                    pbaIdx = 0;
                }
                else if (data[0] == 65)
                {
                    // Private control message.  This isn't an LedWiz message - it's
                    // an extension for this device.  65 is an invalid PBA setting,
                    // and isn't used for any other LedWiz message, so we appropriate
                    // it for our own private use.  The first byte specifies the 
                    // message type.
                    if (data[1] == 1)
                    {
                        // 1 = Set Configuration:
                        //     data[2] = LedWiz unit number (0x00 to 0x0f)
                        //     data[3] = feature enable bit mask:
                        //               0x01 = enable plunger sensor
                        
                        // we'll need a reset if the LedWiz unit number is changing
                        uint8_t newUnitNo = data[2] & 0x0f;
                        needReset |= (newUnitNo != cfg.d.ledWizUnitNo);
                        
                        // set the configuration parameters from the message
                        cfg.d.ledWizUnitNo = newUnitNo;
                        cfg.d.plungerEnabled = data[3] & 0x01;
                        
                        // update the status flags
                        statusFlags = (statusFlags & ~0x01) | (data[3] & 0x01);
                        
                        // if the ccd is no longer enabled, use 0 for z reports
                        if (!cfg.d.plungerEnabled)
                            z = 0;
                        
                        // save the configuration
                        cfg.save(iap, flash_addr);
                    }
#ifdef ENABLE_JOYSTICK
                    else if (data[1] == 2)
                    {
                        // 2 = Calibrate plunger
                        // (No parameters)
                        
                        // enter calibration mode
                        calBtnState = 3;
                        calBtnTimer.reset();
                        cfg.resetPlunger();
                    }
                    else if (data[1] == 3)
                    {
                        // 3 = pixel dump
                        // (No parameters)
                        reportPix = true;
                        
                        // show purple until we finish sending the report
                        ledR = 0;
                        ledB = 0;
                        ledG = 1;
                    }
#endif // ENABLE_JOYSTICK
                }
                else 
                {
                    // LWZ-PBA - full state dump; each byte is one output
                    // in the current bank.  pbaIdx keeps track of the bank;
                    // this is incremented implicitly by each PBA message.
                    //printf("LWZ-PBA[%d] %02x %02x %02x %02x %02x %02x %02x %02x\r\n",
                    //       pbaIdx, data[0], data[1], data[2], data[3], data[4], data[5], data[6], data[7]);
    
                    // update all output profile settings
                    for (int i = 0 ; i < 8 ; ++i)
                        wizVal[pbaIdx + i] = data[i];
    
                    // update the physical LED state if this is the last bank                    
                    if (pbaIdx == 24)
                    {
                        updateWizOuts();
                        pbaIdx = 0;
                    }
                    else
                        pbaIdx += 8;
                }
            }
        }
       
        // check for plunger calibration
        if (calBtn != 0 && !calBtn->read())
        {
            // check the state
            switch (calBtnState)
            {
            case 0: 
                // button not yet pushed - start debouncing
                calBtnTimer.reset();
                calBtnState = 1;
                break;
                
            case 1:
                // pushed, not yet debounced - if the debounce time has
                // passed, start the hold period
                if (calBtnTimer.read_ms() > 50)
                    calBtnState = 2;
                break;
                
            case 2:
                // in the hold period - if the button has been held down
                // for the entire hold period, move to calibration mode
                if (calBtnTimer.read_ms() > 2050)
                {
                    // enter calibration mode
                    calBtnState = 3;
                    calBtnTimer.reset();
                    cfg.resetPlunger();
                }
                break;
                
            case 3:
                // Already in calibration mode - pushing the button here
                // doesn't change the current state, but we won't leave this
                // state as long as it's held down.  So nothing changes here.
                break;
            }
        }
        else
        {
            // Button released.  If we're in calibration mode, and
            // the calibration time has elapsed, end the calibration
            // and save the results to flash.
            //
            // Otherwise, return to the base state without saving anything.
            // If the button is released before we make it to calibration
            // mode, it simply cancels the attempt.
            if (calBtnState == 3 && calBtnTimer.read_ms() > 15000)
            {
                // exit calibration mode
                calBtnState = 0;
                
                // save the updated configuration
                cfg.d.plungerCal = 1;
                cfg.save(iap, flash_addr);
                
                // the flash state is now valid
                flash_valid = true;
            }
            else if (calBtnState != 3)
            {
                // didn't make it to calibration mode - cancel the operation
                calBtnState = 0;
            }
        }       
        
        // light/flash the calibration button light, if applicable
        int newCalBtnLit = calBtnLit;
        switch (calBtnState)
        {
        case 2:
            // in the hold period - flash the light
            newCalBtnLit = ((calBtnTimer.read_ms()/250) & 1);
            break;
            
        case 3:
            // calibration mode - show steady on
            newCalBtnLit = true;
            break;
            
        default:
            // not calibrating/holding - show steady off
            newCalBtnLit = false;
            break;
        }
        
        // light or flash the external calibration button LED, and 
        // do the same with the on-board blue LED
        if (calBtnLit != newCalBtnLit)
        {
            calBtnLit = newCalBtnLit;
            if (calBtnLit) {
                if (calBtnLed != 0)
                    calBtnLed->write(1);
                ledR = 1;
                ledG = 1;
                ledB = 0;
            }
            else {
                if (calBtnLed != 0)
                    calBtnLed->write(0);
                ledR = 1;
                ledG = 1;
                ledB = 1;
            }
        }
        
        // If the plunger is enabled, and we're not already in a firing event,
        // and the last plunger reading had the plunger pulled back at least
        // a bit, watch for plunger release events until it's time for our next
        // USB report.
        if (!firing && cfg.d.plungerEnabled && z >= JOYMAX/6)
        {
            // monitor the plunger until it's time for our next report
            while (reportTimer.read_ms() < 15)
            {
                // do a fast low-res scan; if it's at or past the zero point,
                // start a firing event
                if (plungerSensor.lowResScan() <= cfg.d.plungerZero)
                    firing = 1;
            }
        }

        // read the plunger sensor, if it's enabled
        if (cfg.d.plungerEnabled)
        {
            // start with the previous reading, in case we don't have a
            // clear result on this frame
            int znew = z;
            if (plungerSensor.highResScan(pos))
            {
                // We got a new reading.  If we're in calibration mode, use it
                // to figure the new calibration, otherwise adjust the new reading
                // for the established calibration.
                if (calBtnState == 3)
                {
                    // Calibration mode.  If this reading is outside of the current
                    // calibration bounds, expand the bounds.
                    if (pos < cfg.d.plungerMin)
                        cfg.d.plungerMin = pos;
                    if (pos < cfg.d.plungerZero)
                        cfg.d.plungerZero = pos;
                    if (pos > cfg.d.plungerMax)
                        cfg.d.plungerMax = pos;
                        
                    // normalize to the full physical range while calibrating
                    znew = int(round(float(pos)/npix * JOYMAX));
                }
                else
                {
                    // Not in calibration mode, so normalize the new reading to the 
                    // established calibration range.  
                    //
                    // Note that negative values are allowed.  Zero represents the
                    // "park" position, where the plunger sits when at rest.  A mechanical 
                    // plunger has a small amount of travel in the "push" direction,
                    // since the barrel spring can be compressed slightly.  Negative
                    // values represent travel in the push direction.
                    if (pos > cfg.d.plungerMax)
                        pos = cfg.d.plungerMax;
                    znew = int(round(float(pos - cfg.d.plungerZero)
                        / (cfg.d.plungerMax - cfg.d.plungerZero + 1) * JOYMAX));
                }
            }

            // If we're not already in a firing event, check to see if the
            // new position is forward of the last report.  If it is, a firing
            // event might have started during the high-res scan.  This might
            // seem unlikely given that the scan only takes about 5ms, but that
            // 5ms represents about 25-30% of our total time between reports,
            // there's about a 1 in 4 chance that a release starts during a
            // scan.  
            if (!firing && z0 > 0 && znew < z0)
            {
                // The plunger has moved forward since the previous report.
                // Watch it for a few more ms to see if we can get a stable
                // new position.
                int pos0 = plungerSensor.lowResScan();
                int pos1 = pos0;
                Timer tw;
                tw.start();
                while (tw.read_ms() < 6)
                {
                    // read the new position
                    int pos2 = plungerSensor.lowResScan();
                    
                    // If it's stable over consecutive readings, stop looping.
                    // (Count it as stable if the position is within about 1/8".
                    // pos1 and pos2 are reported in pixels, so they range from
                    // 0 to npix.  The overall travel of a standard plunger is
                    // about 3.2", so we have (npix/3.2) pixels per inch, hence
                    // 1/8" is (npix/3.2)*(1/8) pixels.)
                    if (abs(pos2 - pos1) < int(npix/(3.2*8)))
                        break;

                    // If we've crossed the rest position, and we've moved by
                    // a minimum distance from where we starting this loop, begin
                    // a firing event.  (We require a minimum distance to prevent
                    // spurious firing from random analog noise in the readings
                    // when the plunger is actually just sitting still at the 
                    // rest position.  If it's at rest, it's normal to see small
                    // random fluctuations in the analog reading +/- 1% or so
                    // from the 0 point, especially with a sensor like a
                    // potentionemeter that reports the position as a single 
                    // analog voltage.)  Note that we compare the latest reading
                    // to the first reading of the loop - we don't require the
                    // threshold motion over consecutive readings, but any time
                    // over the stability wait loop.
                    if (pos1 < cfg.d.plungerZero
                        && abs(pos2 - pos0) > int(npix/(3.2*8)))
                    {
                        firing = 1;
                        break;
                    }
                                            
                    // the new reading is now the prior reading
                    pos1 = pos2;
                }
            }
            
            // Check for a simulated Launch Ball button press, if enabled
            if (ZBLaunchBallPort != 0)
            {
                const int cockThreshold = JOYMAX/3;
                const int pushThreshold = int(-JOYMAX/3 * LaunchBallPushDistance);
                int newState = lbState;
                switch (lbState)
                {
                case 0:
                    // Base state.  If the plunger is pulled back by an inch
                    // or more, go to "cocked" state.  If the plunger is pushed
                    // forward by 1/4" or more, go to "pressed" state.
                    if (znew >= cockThreshold)
                        newState = 1;
                    else if (znew <= pushThreshold)
                        newState = 5;
                    break;
                    
                case 1:
                    // Cocked state.  If a firing event is now in progress,
                    // go to "launch" state.  Otherwise, if the plunger is less
                    // than 1" retracted, go to "uncocked" state - the player
                    // might be slowly returning the plunger to rest so as not
                    // to trigger a launch.
                    if (firing || znew <= 0)
                        newState = 3;
                    else if (znew < cockThreshold)
                        newState = 2;
                    break;
                    
                case 2:
                    // Uncocked state.  If the plunger is more than an inch
                    // retracted, return to cocked state.  If we've been in
                    // the uncocked state for more than half a second, return
                    // to the base state.  This allows the user to return the
                    // plunger to rest without triggering a launch, by moving
                    // it at manual speed to the rest position rather than
                    // releasing it.
                    if (znew >= cockThreshold)
                        newState = 1;
                    else if (lbTimer.read_ms() > 500)
                        newState = 0;
                    break;
                    
                case 3:
                    // Launch state.  If the plunger is no longer pushed
                    // forward, switch to launch rest state.
                    if (znew >= 0)
                        newState = 4;
                    break;    
                    
                case 4:
                    // Launch rest state.  If the plunger is pushed forward
                    // again, switch back to launch state.  If not, and we've
                    // been in this state for at least 200ms, return to the
                    // default state.
                    if (znew <= pushThreshold)
                        newState = 3;
                    else if (lbTimer.read_ms() > 200)
                        newState = 0;                    
                    break;
                    
                case 5:
                    // Press-and-Hold state.  If the plunger is no longer pushed
                    // forward, AND it's been at least 50ms since we generated
                    // the simulated Launch Ball button press, return to the base 
                    // state.  The minimum time is to ensure that VP has a chance
                    // to see the button press and to avoid transient key bounce
                    // effects when the plunger position is right on the threshold.
                    if (znew > pushThreshold && lbTimer.read_ms() > 50)
                        newState = 0;
                    break;
                }
                
                // change states if desired
                const uint32_t lbButtonBit = (1 << (LaunchBallButton - 1));
                if (newState != lbState)
                {
                    // If we're entering Launch state OR we're entering the
                    // Press-and-Hold state, AND the ZB Launch Ball LedWiz signal 
                    // is turned on, simulate a Launch Ball button press.
                    if (((newState == 3 && lbState != 4) || newState == 5)
                        && wizOn[ZBLaunchBallPort-1])
                    {
                        lbBtnTimer.reset();
                        lbBtnTimer.start();
                        simButtons |= lbButtonBit;
                    }
                    
                    // if we're switching to state 0, release the button
                    if (newState == 0)
                        simButtons &= ~(1 << (LaunchBallButton - 1));
                    
                    // switch to the new state
                    lbState = newState;
                    
                    // start timing in the new state
                    lbTimer.reset();
                }
                
                // If the Launch Ball button press is in effect, but the
                // ZB Launch Ball LedWiz signal is no longer turned on, turn
                // off the button.
                //
                // If we're in one of the Launch states (state #3 or #4),
                // and the button has been on for long enough, turn it off.
                // The Launch mode is triggered by a pull-and-release gesture.
                // From the user's perspective, this is just a single gesture
                // that should trigger just one momentary press on the Launch
                // Ball button.  Physically, though, the plunger usually
                // bounces back and forth for 500ms or so before coming to
                // rest after this gesture.  That's what the whole state
                // #3-#4 business is all about - we stay in this pair of
                // states until the plunger comes to rest.  As long as we're
                // in these states, we won't send duplicate button presses.
                // But we also don't want the one button press to continue 
                // the whole time, so we'll time it out now.
                //
                // (This could be written as one big 'if' condition, but
                // I'm breaking it out verbosely like this to make it easier
                // for human readers such as myself to comprehend the logic.)
                if ((simButtons & lbButtonBit) != 0)
                {
                    int turnOff = false;
                    
                    // turn it off if the ZB Launch Ball signal is off
                    if (!wizOn[ZBLaunchBallPort-1])
                        turnOff = true;
                        
                    // also turn it off if we're in state 3 or 4 ("Launch"),
                    // and the button has been on long enough
                    if ((lbState == 3 || lbState == 4) && lbBtnTimer.read_ms() > 250)
                        turnOff = true;
                        
                    // if we decided to turn off the button, do so
                    if (turnOff)
                    {
                        lbBtnTimer.stop();
                        simButtons &= ~lbButtonBit;
                    }
                }
            }
                
            // If a firing event is in progress, generate synthetic reports to 
            // describe an idealized version of the plunger motion to VP rather 
            // than reporting the actual physical plunger position.
            //
            // We use the synthetic reports during a release event because the
            // physical plunger motion when released is too fast for VP to track.
            // VP only syncs its internal physics model with the outside world 
            // about every 10ms.  In that amount of time, the plunger moves
            // fast enough when released that it can shoot all the way forward,
            // bounce off of the barrel spring, and rebound part of the way
            // back.  The result is the classic analog-to-digital problem of
            // sample aliasing.  If we happen to time our sample during the
            // release motion so that we catch the plunger at the peak of a
            // bounce, the digital signal incorrectly looks like the plunger
            // is moving slowly forward - VP thinks we went from fully
            // retracted to half retracted in the sample interval, whereas
            // we actually traveled all the way forward and half way back,
            // so the speed VP infers is about 1/3 of the actual speed.
            //
            // To correct this, we take advantage of our ability to sample 
            // the CCD image several times in the course of a VP report.  If
            // we catch the plunger near the origin after we've seen it
            // retracted, we go into Release Event mode.  During this mode,
            // we stop reporting the true physical plunger position, and
            // instead report an idealized pattern: we report the plunger
            // immediately shooting forward to a position in front of the
            // park position that's in proportion to how far back the plunger
            // was just before the release, and we then report it stationary
            // at the park position.  We continue to report the stationary
            // park position until the actual physical plunger motion has
            // stabilized on a new position.  We then exit Release Event
            // mode and return to reporting the true physical position.
            if (firing)
            {
                // Firing in progress.  Keep reporting the park position
                // until the physical plunger position comes to rest.
                const int restTol = JOYMAX/24;
                if (firing == 1)
                {
                    // For the first couple of frames, show the plunger shooting
                    // forward past the zero point, to simulate the momentum carrying
                    // it forward to bounce off of the barrel spring.  Show the 
                    // bounce as proportional to the distance it was retracted
                    // in the prior report.
                    z = zBounce = -z0/6;
                    ++firing;
                }
                else if (firing == 2)
                {
                    // second frame - keep the bounce a little longer
                    z = zBounce;
                    ++firing;
                }
                else if (firing > 4
                    && abs(znew - z0) < restTol
                    && abs(znew - z1) < restTol 
                    && abs(znew - z2) < restTol)
                {
                    // The physical plunger has come to rest.  Exit firing
                    // mode and resume reporting the actual position.
                    firing = false;
                    z = znew;
                }
                else
                {
                    // until the physical plunger comes to rest, simply 
                    // report the park position
                    z = 0;
                    ++firing;
                }
            }
            else
            {
                // not in firing mode - report the true physical position
                z = znew;
            }

            // shift the new reading into the recent history buffer
            z2 = z1;
            z1 = z0;
            z0 = znew;
        }

        // update the buttons
        uint32_t buttons = readButtons();

#ifdef ENABLE_JOYSTICK
        // If it's been long enough since our last USB status report,
        // send the new report.  We throttle the report rate because
        // it can overwhelm the PC side if we report too frequently.
        // VP only wants to sync with the real world in 10ms intervals,
        // so reporting more frequently only creates i/o overhead
        // without doing anything to improve the simulation.
        if (reportTimer.read_ms() > 15)
        {
            // read the accelerometer
            int xa, ya;
            accel.get(xa, ya);
            
            // confine the results to our joystick axis range
            if (xa < -JOYMAX) xa = -JOYMAX;
            if (xa > JOYMAX) xa = JOYMAX;
            if (ya < -JOYMAX) ya = -JOYMAX;
            if (ya > JOYMAX) ya = JOYMAX;
            
            // store the updated accelerometer coordinates
            x = xa;
            y = ya;
            
            // Report the current plunger position UNLESS the ZB Launch Ball 
            // signal is on, in which case just report a constant 0 value.  
            // ZB Launch Ball turns off the plunger position because it
            // tells us that the table has a Launch Ball button instead of
            // a traditional plunger.
            int zrep = (ZBLaunchBallPort != 0 && wizOn[ZBLaunchBallPort-1] ? 0 : z);
            
            // Send the status report.  Note that we have to map the X and Y
            // axes from the accelerometer to match the Windows joystick axes.
            // The mapping is determined according to the mounting direction
            // set in config.h via the ORIENTATION_xxx macros.
            js.update(JOY_X(x,y), JOY_Y(x,y), zrep, buttons | simButtons, statusFlags);
            
            // we've just started a new report interval, so reset the timer
            reportTimer.reset();
        }

        // If we're in pixel dump mode, report all pixel exposure values
        if (reportPix)
        {
            // send the report            
            plungerSensor.sendExposureReport(js);

            // we have satisfied this request
            reportPix = false;
        }
        
#else // ENABLE_JOYSTICK
        // We're a secondary controller, with no joystick reporting.  Send
        // a generic status report to the host periodically for the sake of
        // the Windows config tool.
        if (reportTimer.read_ms() > 200)
        {
            js.updateStatus(0);
        }

#endif // ENABLE_JOYSTICK
        
#ifdef DEBUG_PRINTF
        if (x != 0 || y != 0)
            printf("%d,%d\r\n", x, y);
#endif

        // provide a visual status indication on the on-board LED
        if (calBtnState < 2 && hbTimer.read_ms() > 1000) 
        {
            if (js.isSuspended() || !js.isConnected())
            {
                // suspended - turn off the LED
                ledR = 1;
                ledG = 1;
                ledB = 1;

                // show a status flash every so often                
                if (hbcnt % 3 == 0)
                {
                    // disconnected = red/red flash; suspended = red
                    for (int n = js.isConnected() ? 1 : 2 ; n > 0 ; --n)
                    {
                        ledR = 0;
                        wait(0.05);
                        ledR = 1;
                        wait(0.25);
                    }
                }
            }
            else if (needReset)
            {
                // connected, need to reset due to changes in config parameters -
                // flash red/green
                hb = !hb;
                ledR = (hb ? 0 : 1);
                ledG = (hb ? 1 : 0);
                ledB = 0;
            }
            else if (cfg.d.plungerEnabled && !cfg.d.plungerCal)
            {
                // connected, plunger calibration needed - flash yellow/green
                hb = !hb;
                ledR = (hb ? 0 : 1);
                ledG = 0;
                ledB = 1;
            }
            else
            {
                // connected - flash blue/green
                hb = !hb;
                ledR = 1;
                ledG = (hb ? 0 : 1);
                ledB = (hb ? 1 : 0);
            }
            
            // reset the heartbeat timer
            hbTimer.reset();
            ++hbcnt;
        }
    }
}