Mike R / Mbed 2 deprecated Pinscape_Controller

An input/output controller for virtual pinball machines, with plunger position tracking, accelerometer-based nudge sensing, button input encoding, and feedback device control.

Dependencies:   USBDevice mbed FastAnalogIn FastIO FastPWM SimpleDMA

The Pinscape Controller is a special-purpose software project that I wrote for my virtual pinball machine.

New version: V2 is now available! The information below is for version 1, which will continue to be available for people who prefer the original setup.

What exactly is a virtual pinball machine? It's basically a video-game pinball emulator built to look like a real pinball machine. (The picture at right is the one I built.) You start with a standard pinball cabinet, either built from scratch or salvaged from a real machine. Inside, you install a PC motherboard to run the software, and install TVs in place of the playfield and backglass. Several Windows pinball programs can take advantage of this setup, including the open-source project Visual Pinball, which has hundreds of tables available. Building one of these makes a great DIY project, and it's a good way to add to your skills at woodworking, computers, and electronics. Check out the Cabinet Builders' Forum on vpforums.org for lots of examples and advice.

This controller project is a key piece in my setup that helps integrate the video game into the pinball cabinet. It handles several input/output tasks that are unique to virtual pinball machines. First, it lets you connect a mechanical plunger to the software, so you can launch the ball like on a real machine. Second, it sends "nudge" data to the software, based on readings from an accelerometer. This lets you interact with the game physically, which makes the playing experience more realistic and immersive. Third, the software can handle button input (for wiring flipper buttons and other cabinet buttons), and fourth, it can control output devices (for tactile feedback, button lights, flashers, and other special effects).

Documentation

The Hardware Build Guide (PDF) has detailed instructions on how to set up a Pinscape Controller for your own virtual pinball cabinet.

Update notes

December 2015 version: This version fully supports the new Expansion Board project, but it'll also run without it. The default configuration settings haven't changed, so existing setups should continue to work as before.

August 2015 version: Be sure to get the latest version of the Config Tool for windows if you're upgrading from an older version of the firmware. This update adds support for TSL1412R sensors (a version of the 1410 sensor with a slightly larger pixel array), and a config option to set the mounting orientation of the board in the firmware rather than in VP (for better support for FP and other pinball programs that don't have VP's flexibility for setting the rotation).

Feb/March 2015 software versions: If you have a CCD plunger that you've been using with the older versions, and the plunger stops working (or doesn't work as well) after you update to the latest version, you might need to increase the brightness of your light source slightly. Check the CCD exposure with the Windows config tool to see if it looks too dark. The new software reads the CCD much more quickly than the old versions did. This makes the "shutter speed" faster, which might require a little more light to get the same readings. The CCD is actually really tolerant of varying light levels, so you probably won't have to change anything for the update - I didn't. But if you do have any trouble, have a look at the exposure meter and try a slightly brighter light source if the exposure looks too dark.

Downloads

• Config tool for Windows (.exe and C# source): this is a Windows program that lets you view the raw pixel data from the CCD sensor, trigger plunger calibration mode, and configure some of the software options on the controller.

• 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 9.9.1 and VP 10 releases, so you don't need my custom builds if you're using 9.9.1 or 10 or later. I don't think there's any reason to use my 9.9 instead of the official 9.9.1, but I'm leaving it here just in case. In the official VP releases, look for the checkbox "Enable Nudge Filter" in the Keys preferences dialog. (There's no checkbox in my custom builds, though; the filter is simply always on in those.)

• Output circuit shopping list: This is a saved shopping cart at mouser.com with the parts needed for each output driver, if you want to use the LedWiz emulator feature. Note that quantities in the cart are for one output channel, so multiply everything by the number of channels you plan to use, except that you only need one of the ULN2803 transistor array chips for each eight output circuits.

• 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.

Features

• Plunger position sensing, using a TAOS TSL 1410R CCD linear array sensor. This sensor is a 1280 x 1 pixel array at 400 dpi, which makes it about 3" long - almost exactly the travel distance of a standard pinball plunger. The idea is that you install the sensor just above (within a few mm of) the shooter rod on the inside of the cabinet, with the CCD window facing down, aligned with and centered on the long axis of the shooter rod, and positioned so that the rest position of the tip is about 1/2" from one end of the window. As you pull back the plunger, the tip will travel down the length of the window, and the maximum retraction point will put the tip just about at the far end of the window. Put a light source below, facing the sensor - I'm using two typical 20 mA blue LEDs about 8" away (near the floor of the cabinet) with good results. The principle of operation is that the shooter rod casts a shadow on the CCD, so pixels behind the rod will register lower brightness than pixels that aren't in the shadow. We scan down the length of the sensor for the edge between darker and brighter, and this tells us how far back the rod has been pulled. We can read the CCD at about 25-30 ms intervals, so we can get rapid updates. We pass the readings reports to VP via our USB joystick reports.
  
  The hardware build guide includes schematics showing how to wire the CCD to the KL25Z. It's pretty straightforward - five wires between the two devices, no external components needed. Two GPIO ports are used as outputs to send signals to the device and one is used as an ADC in to read the pixel brightness inputs. The config tool has a feature that lets you display the raw pixel readings across the array, so you can test that the CCD is working and adjust the light source to get the right exposure level.
  
  Alternatively, you can use a slide potentiometer as the plunger sensor. This is a cheaper and somewhat simpler option that seems to work quite nicely, as you can see in Lemming77's video of this setup in action. This option is also explained more fully in the build guide.

• Nudge sensing via the KL25Z's on-board accelerometer. Mounting the board in your cabinet makes it feel the same accelerations the cabinet experiences when you nudge it. Visual Pinball already knows how to interpret accelerometer input as nudging, so we simply feed the acceleration readings to VP via the joystick interface.

• Cabinet button wiring. Up to 24 pushbuttons and switches can be wired to the controller for input controls (for example, flipper buttons, the Start button, the tilt bob, coin slot switches, and service door buttons). These appear to Windows as joystick buttons. VP can map joystick buttons to pinball inputs via its keyboard preferences dialog. (You can raise the 24-button limit by editing the source code, but since all of the GPIO pins are allocated, you'll have to reassign pins currently used for other functions.)

• LedWiz emulation (limited). In addition to emulating a joystick, the device emulates the LedWiz USB interface, so controllers on the PC side such as DirectOutput Framework can recognize it and send it commands to control lights, solenoids, and other feedback devices. 22 GPIO ports are assigned by default as feedback device outputs. This feature has some limitations. The big one is that the KL25Z hardware only has 10 PWM channels, which isn't enough for a fully decked-out cabinet. You also need to build some external power driver circuitry to use this feature, because of the paltry 4mA output capacity of the KL25Z GPIO ports. The build guide includes instructions for a simple and robust output circuit, including part numbers for the exact components you need. It's not hard if you know your way around a soldering iron, but just be aware that it'll take a little work.

Warning: This is not replacement software for the VirtuaPin plunger kit. If you bought the VirtuaPin kit, please don't try to install this software. The VP kit happens to use the same microcontroller board, but the rest of its hardware is incompatible. The VP kit uses a different type of sensor for its plunger and has completely different button wiring, so the Pinscape software won't work properly with it.

// CCD plunger sensor
//
// This file implements our generic plunger sensor interface for the 
// TAOS TSL1410R CCD array sensor.



// Number of pixels we read from the CCD on each frame.  Use the
// sample size from config.h.
const int npix = CCD_NPIXELS_SAMPLED;

// PlungerSensor interface implementation for the CCD
class PlungerSensor
{
public:
    PlungerSensor() : ccd(CCD_SO_PIN)
    {
    }
    
    // initialize
    void init()
    {
        // flush any random power-on values from the CCD's integration
        // capacitors, and start the first integration cycle
        ccd.clear();
    }
    
    // Perform a low-res scan of the sensor.  
    int lowResScan()
    {
        // read the pixels at low resolution
        const int nlpix = 32;
        uint16_t pix[nlpix];
        ccd.read(pix, nlpix);
    
        // determine which end is brighter
        uint16_t p1 = pix[0];
        uint16_t p2 = pix[nlpix-1];
        int si = 0, di = 1;
        if (p1 < p2)
            si = nlpix - 1, di = -1;
        
        // figure the shadow edge threshold - just use the midpoint 
        // of the levels at the bright and dark ends
        uint16_t shadow = uint16_t((long(p1) + long(p2))/2);
        
        // find the current tip position
        for (int n = 0 ; n < nlpix ; ++n, si += di)
        {
            // check to see if we found the shadow
            if (pix[si] <= shadow)
            {
                // got it - normalize it to normal 'npix' resolution and
                // return the result
                return n*npix/nlpix;
            }
        }
        
        // didn't find a shadow - assume the whole array is in shadow (so
        // the edge is at the zero pixel point)
        return 0;
    }

    // Perform a high-res scan of the sensor.
    bool highResScan(int &pos)
    {
        // read the array
        ccd.read(pix, npix);

        // get the brightness at each end of the sensor
        long b1 = pix[0];
        long b2 = pix[npix-1];
        
        // Work from the bright end to the dark end.  VP interprets the
        // Z axis value as the amount the plunger is pulled: zero is the
        // rest position, and the axis maximum is fully pulled.  So we 
        // essentially want to report how much of the sensor is lit,
        // since this increases as the plunger is pulled back.
        int si = 0, di = 1;
        long hi = b1;
        if (b1 < b2)
            si = npix - 1, di = -1, hi = b2;

        // Figure the shadow threshold.  In practice, the portion of the
        // sensor that's not in shadow has all pixels consistently near
        // saturation; the first drop in brightness is pretty reliably the
        // start of the shadow.  So set the threshold level to be closer
        // to the bright end's brightness level, so that we detect the leading
        // edge if the shadow isn't perfectly sharp.  Use the point 1/3 of
        // the way down from the high top the low side, so:
        //
        //   threshold = lo + (hi - lo)*2/3
        //             = lo + hi*2/3 - lo*2/3
        //             = lo - lo*2/3 + hi*2/3
        //             = lo*1/3 + hi*2/3
        //             = (lo + hi*2)/3
        //
        // Now, 'lo' is always one of b1 or b2, and 'hi' is the other
        // one, so we can rewrite this as:
        long midpt = (b1 + b2 + hi)/3;
        
        // If we have enough contrast, proceed with the scan.
        //
        // If the bright end and dark end don't differ by enough, skip this
        // reading entirely.  Either we have an overexposed or underexposed frame,
        // or the sensor is misaligned and is either fully in or out of shadow
        // (it's supposed to be mounted such that the edge of the shadow always
        // falls within the sensor, for any possible plunger position).
        if (labs(b1 - b2) > 0x1000)
        {
            uint16_t *pixp = pix + si;           
            for (int n = 0 ; n < npix ; ++n, pixp += di)
            {
                // if we've crossed the midpoint, report this position
                if (long(*pixp) < midpt)
                {
                    // note the new position
                    pos = n;
                    return true;
                }
            }
        }
        
        // we didn't find a shadow - return no reading
        return false;
    }
    
    // send an exposure report to the joystick interface
    void sendExposureReport(USBJoystick &js)
    {
        // send reports for all pixels
        int idx = 0;
        while (idx < npix)
        {
            js.updateExposure(idx, npix, pix);
            wait_ms(1);
        }
            
        // The pixel dump requires many USB reports, since each report
        // can only send a few pixel values.  An integration cycle has
        // been running all this time, since each read starts a new
        // cycle.  Our timing is longer than usual on this round, so
        // the integration won't be comparable to a normal cycle.  Throw
        // this one away by doing a read now, and throwing it away - that 
        // will get the timing of the *next* cycle roughly back to normal.
        ccd.read(pix, npix);
    }
    
private:
    // pixel buffer
    uint16_t pix[npix];
    
    // the low-level interface to the CCD hardware
    TSL1410R<CCD_SI_PIN, CCD_CLOCK_PIN> ccd;
};