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.

Committer:
mjr
Date:
Sat Apr 18 19:08:55 2020 +0000
Revision:
109:310ac82cbbee
Parent:
106:e9e3b46132c1
TCD1103 DMA setup time padding to fix sporadic missed first pixel in transfer; fix TV ON so that the TV ON IR commands don't have to be grouped in the IR command first slots

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 100:1ff35c07217c 1 // Toshiba TCD1103 linear image sensors
mjr 100:1ff35c07217c 2 //
mjr 100:1ff35c07217c 3 // This sensor is similar to the original TSL1410R in both its electronic
mjr 100:1ff35c07217c 4 // interface and the theory of operation. The details of the electronics
mjr 100:1ff35c07217c 5 // are different enough that we can't reuse the same code at the hardware
mjr 100:1ff35c07217c 6 // interface level, but the principle of operation is similar: the sensor
mjr 100:1ff35c07217c 7 // provides a serial interface to a file of pixels transferred as analog
mjr 100:1ff35c07217c 8 // voltage levels representing the charge collected.
mjr 100:1ff35c07217c 9 //
mjr 100:1ff35c07217c 10 // As with the TSL1410R, we position the sensor so that the pixel row is
mjr 104:6e06e0f4b476 11 // aligned with the plunger axis, and we detect the plunger position by
mjr 104:6e06e0f4b476 12 // looking for a dark/light edge at the end of the plunger. However,
mjr 104:6e06e0f4b476 13 // the optics for this sensor are very different because of the sensor's
mjr 104:6e06e0f4b476 14 // size. The TSL1410R is by some magical coincidence the same size as
mjr 104:6e06e0f4b476 15 // the plunger travel range, so we set that sensor up so that the plunger
mjr 104:6e06e0f4b476 16 // is backlit with respect to the sensor, and simply casts a shadow on
mjr 104:6e06e0f4b476 17 // the sensor. The TCD1103, in contrast, has a pixel array that's only
mjr 104:6e06e0f4b476 18 // 8mm long, so we can't use the direct shadow approach. Instead, we
mjr 104:6e06e0f4b476 19 // have to use a lens to focus an image of the plunger on the sensor.
mjr 104:6e06e0f4b476 20 // With a focused image, we can front-light the plunger and take a picture
mjr 104:6e06e0f4b476 21 // of the plunger itself rather than of an occluded back-light.
mjr 100:1ff35c07217c 22 //
mjr 104:6e06e0f4b476 23 // Even though we use "edge sensing", this class isn't based on the
mjr 104:6e06e0f4b476 24 // PlungerSensorEdgePos class. Our sensing algorithm is a little different,
mjr 104:6e06e0f4b476 25 // and much simpler, because we're working with a proper image of the
mjr 104:6e06e0f4b476 26 // plunger, rather than an image of its shadow. The shadow tends to be
mjr 104:6e06e0f4b476 27 // rather fuzzy, and the TSL14xx sensors were pretty noisy, so we had to
mjr 104:6e06e0f4b476 28 // work fairly hard to distinguish an edge in the image from a noise spike.
mjr 104:6e06e0f4b476 29 // This sensor has very low noise, and the focused image produces a sharp
mjr 104:6e06e0f4b476 30 // edge, so we can use a more straightforward algorithm that just looks
mjr 104:6e06e0f4b476 31 // for the first bright spot.
mjr 104:6e06e0f4b476 32 //
mjr 104:6e06e0f4b476 33 // The TCD1103 uses a negative image: brighter pixels are represented by
mjr 104:6e06e0f4b476 34 // lower numbers. The electronics of the sensor are such that the dynamic
mjr 104:6e06e0f4b476 35 // range for the pixel analag voltage signal (which is what our pixel
mjr 104:6e06e0f4b476 36 // elements represent) is only about 1V, or about 30% of the 3.3V range of
mjr 104:6e06e0f4b476 37 // the ADC. Dark pixels read at about 2V (about 167 after 8-bit ADC
mjr 104:6e06e0f4b476 38 // quantization), and saturated pixels read at 1V (78 on the ADC). So our
mjr 104:6e06e0f4b476 39 // effective dynamic range after quantization is about 100 steps. That
mjr 104:6e06e0f4b476 40 // would be pretty terrible if the goal were to take pictures for an art
mjr 104:6e06e0f4b476 41 // gallery, and there are things we could do in the electronic interface
mjr 106:e9e3b46132c1 42 // to improve it. In particular, we could use an op-amp to expand the
mjr 104:6e06e0f4b476 43 // voltage range on the ADC input and remove the DC offset, so that the
mjr 106:e9e3b46132c1 44 // signal going into the ADC covers the ADC's full 0V - 3.3V range. That
mjr 106:e9e3b46132c1 45 // technique is actually used in some other projects using this sensor
mjr 106:e9e3b46132c1 46 // where the goal is to yield pictures as the end result. But it's
mjr 106:e9e3b46132c1 47 // pretty complicated to set up and fine-tune to get the voltage range
mjr 106:e9e3b46132c1 48 // expansion just right, and we really don't need it; the edge detection
mjr 106:e9e3b46132c1 49 // works fine with what we get directly from the sensor.
mjr 106:e9e3b46132c1 50
mjr 100:1ff35c07217c 51
mjr 104:6e06e0f4b476 52
mjr 104:6e06e0f4b476 53 #include "plunger.h"
mjr 100:1ff35c07217c 54 #include "TCD1103.h"
mjr 100:1ff35c07217c 55
mjr 100:1ff35c07217c 56 template <bool invertedLogicGates>
mjr 100:1ff35c07217c 57 class PlungerSensorImageInterfaceTCD1103: public PlungerSensorImageInterface
mjr 100:1ff35c07217c 58 {
mjr 100:1ff35c07217c 59 public:
mjr 100:1ff35c07217c 60 PlungerSensorImageInterfaceTCD1103(PinName fm, PinName os, PinName icg, PinName sh)
mjr 109:310ac82cbbee 61 : PlungerSensorImageInterface(1546), sensor(fm, os, icg, sh)
mjr 100:1ff35c07217c 62 {
mjr 100:1ff35c07217c 63 }
mjr 100:1ff35c07217c 64
mjr 100:1ff35c07217c 65 // is the sensor ready?
mjr 100:1ff35c07217c 66 virtual bool ready() { return sensor.ready(); }
mjr 100:1ff35c07217c 67
mjr 101:755f44622abc 68 virtual void init() { }
mjr 100:1ff35c07217c 69
mjr 100:1ff35c07217c 70 // get the average sensor scan time
mjr 100:1ff35c07217c 71 virtual uint32_t getAvgScanTime() { return sensor.getAvgScanTime(); }
mjr 100:1ff35c07217c 72
mjr 101:755f44622abc 73 virtual void readPix(uint8_t* &pix, uint32_t &t)
mjr 100:1ff35c07217c 74 {
mjr 100:1ff35c07217c 75 // get the image array from the last capture
mjr 104:6e06e0f4b476 76 sensor.getPix(pix, t);
mjr 100:1ff35c07217c 77 }
mjr 100:1ff35c07217c 78
mjr 101:755f44622abc 79 virtual void releasePix() { sensor.releasePix(); }
mjr 101:755f44622abc 80
mjr 101:755f44622abc 81 virtual void setMinIntTime(uint32_t us) { sensor.setMinIntTime(us); }
mjr 100:1ff35c07217c 82
mjr 100:1ff35c07217c 83 // the low-level interface to the TSL14xx sensor
mjr 100:1ff35c07217c 84 TCD1103<invertedLogicGates> sensor;
mjr 100:1ff35c07217c 85 };
mjr 100:1ff35c07217c 86
mjr 100:1ff35c07217c 87 template<bool invertedLogicGates>
mjr 104:6e06e0f4b476 88 class PlungerSensorTCD1103: public PlungerSensorImage<int>
mjr 100:1ff35c07217c 89 {
mjr 100:1ff35c07217c 90 public:
mjr 100:1ff35c07217c 91 PlungerSensorTCD1103(PinName fm, PinName os, PinName icg, PinName sh)
mjr 109:310ac82cbbee 92 : PlungerSensorImage(sensor, 1546, 1545, true), sensor(fm, os, icg, sh)
mjr 100:1ff35c07217c 93 {
mjr 100:1ff35c07217c 94 }
mjr 100:1ff35c07217c 95
mjr 100:1ff35c07217c 96 protected:
mjr 104:6e06e0f4b476 97 // Process an image. This seeks the first dark-to-light edge in the image.
mjr 104:6e06e0f4b476 98 // We assume that the background (open space behind the plunger) has a
mjr 104:6e06e0f4b476 99 // dark (minimally reflective) backdrop, and that the tip of the plunger
mjr 104:6e06e0f4b476 100 // has a bright white strip right at the end. So the end of the plunger
mjr 104:6e06e0f4b476 101 // should be easily identifiable in the image as the first bright edge
mjr 104:6e06e0f4b476 102 // we see starting at the "far" end.
mjr 104:6e06e0f4b476 103 virtual bool process(const uint8_t *pix, int n, int &pos, int& /*processResult*/)
mjr 104:6e06e0f4b476 104 {
mjr 109:310ac82cbbee 105 // The TCD1103's pixel file that it reports on the wire has the
mjr 109:310ac82cbbee 106 // following internal structure:
mjr 109:310ac82cbbee 107 //
mjr 109:310ac82cbbee 108 // 16 dummy elements, fixed at the dark charge level
mjr 109:310ac82cbbee 109 // 13 light-shielded pixels (live pixels, covered with a shade in the sensor)
mjr 109:310ac82cbbee 110 // 3 dummy "buffer" pixels (to allow for variation in shade alignment)
mjr 109:310ac82cbbee 111 // 1500 image pixels
mjr 109:310ac82cbbee 112 // 14 dummy elements (the data sheet doesn't say exactly what these are physically)
mjr 109:310ac82cbbee 113 //
mjr 109:310ac82cbbee 114 // The sensor holds the 16 dummy elements at the dark charge level,
mjr 109:310ac82cbbee 115 // so they provide a reference point for the darkest reading possible.
mjr 109:310ac82cbbee 116 // The light-shielded pixels serve essentially the same purpose, in
mjr 109:310ac82cbbee 117 // that they *also* should read out at the dark charge level. But
mjr 109:310ac82cbbee 118 // the shaded pixels can be also used for diagnostics, to distinguish
mjr 109:310ac82cbbee 119 // between problems in the CCD proper and problems in the interface
mjr 109:310ac82cbbee 120 // electronics. If the dummy elements are reading at the dark level
mjr 109:310ac82cbbee 121 // but the shielded pixels aren't, you have a CCD problem; if the
mjr 109:310ac82cbbee 122 // dummy pixels aren't reading at the dark level, the interface
mjr 109:310ac82cbbee 123 // electronics are suspect.
mjr 109:310ac82cbbee 124 //
mjr 109:310ac82cbbee 125 // For our purposes, we can simply ignore the dummy pixels at either
mjr 109:310ac82cbbee 126 // end. The diagnostic status report for the Config Tool sends the
mjr 109:310ac82cbbee 127 // full view including the dummy pixels, so any diagnostics that the
mjr 109:310ac82cbbee 128 // user wants to do using the dummy pixels can be done on the PC side.
mjr 109:310ac82cbbee 129 //
mjr 109:310ac82cbbee 130 // Deduct the dummy pixels so that we only scan the true image
mjr 109:310ac82cbbee 131 // pixels in our search for the plunger edge.
mjr 109:310ac82cbbee 132 int startOfs = 32;
mjr 109:310ac82cbbee 133 n -= 32 + 14;
mjr 109:310ac82cbbee 134
mjr 104:6e06e0f4b476 135 // Scan the pixel array to determine the actual dynamic range
mjr 104:6e06e0f4b476 136 // of this image. That will let us determine what consistutes
mjr 104:6e06e0f4b476 137 // "bright" when we're looking for the bright spot.
mjr 104:6e06e0f4b476 138 uint8_t pixMin = 255, pixMax = 0;
mjr 109:310ac82cbbee 139 const uint8_t *p = pix + startOfs;
mjr 104:6e06e0f4b476 140 for (int i = n; i != 0; --i)
mjr 104:6e06e0f4b476 141 {
mjr 104:6e06e0f4b476 142 uint8_t c = *p++;
mjr 104:6e06e0f4b476 143 if (c < pixMin) pixMin = c;
mjr 104:6e06e0f4b476 144 if (c > pixMax) pixMax = c;
mjr 104:6e06e0f4b476 145 }
mjr 104:6e06e0f4b476 146
mjr 104:6e06e0f4b476 147 // Figure the threshold brightness for the bright spot as halfway
mjr 104:6e06e0f4b476 148 // between the min and max.
mjr 104:6e06e0f4b476 149 uint8_t threshold = (pixMin + pixMax)/2;
mjr 104:6e06e0f4b476 150
mjr 104:6e06e0f4b476 151 // Scan for the first bright-enough pixel. Remember that we're
mjr 104:6e06e0f4b476 152 // working with a negative image, so "brighter" is "less than".
mjr 109:310ac82cbbee 153 p = pix + startOfs;
mjr 104:6e06e0f4b476 154 for (int i = n; i != 0; --i, ++p)
mjr 104:6e06e0f4b476 155 {
mjr 104:6e06e0f4b476 156 if (*p < threshold)
mjr 104:6e06e0f4b476 157 {
mjr 104:6e06e0f4b476 158 // got it - report this position
mjr 104:6e06e0f4b476 159 pos = p - pix;
mjr 104:6e06e0f4b476 160 return true;
mjr 104:6e06e0f4b476 161 }
mjr 104:6e06e0f4b476 162 }
mjr 104:6e06e0f4b476 163
mjr 104:6e06e0f4b476 164 // no edge found - report failure
mjr 104:6e06e0f4b476 165 return false;
mjr 104:6e06e0f4b476 166 }
mjr 104:6e06e0f4b476 167
mjr 104:6e06e0f4b476 168 // Use a fixed orientation for this sensor. The shadow-edge sensors
mjr 104:6e06e0f4b476 169 // try to infer the direction by checking which end of the image is
mjr 104:6e06e0f4b476 170 // brighter, which works well for the shadow sensors because the back
mjr 104:6e06e0f4b476 171 // end of the image will always be in shadow. But for this sensor,
mjr 104:6e06e0f4b476 172 // we're taking an image of the plunger (not its shadow), and the
mjr 104:6e06e0f4b476 173 // back end of the plunger is the part with the spring, which has a
mjr 104:6e06e0f4b476 174 // fuzzy and complex reflectivity pattern because of the spring.
mjr 104:6e06e0f4b476 175 // So for this sensor, it's better to insist that the user sets it
mjr 104:6e06e0f4b476 176 // up in a canonical orientation. That's a reasaonble expectation
mjr 104:6e06e0f4b476 177 // for this sensor anyway, because the physical installation won't
mjr 104:6e06e0f4b476 178 // be as ad hoc as the TSL1410R setup, which only required that you
mjr 104:6e06e0f4b476 179 // mounted the sensor itself. In this case, you have to build a
mjr 104:6e06e0f4b476 180 // circuit board and mount a lens on it, so it's reasonable to
mjr 104:6e06e0f4b476 181 // expect that everyone will be using the mounting apparatus plans
mjr 104:6e06e0f4b476 182 // that we'll detail in the build guide. In any case, we'll just
mjr 104:6e06e0f4b476 183 // make it clear in the instructions that you have to mount the
mjr 104:6e06e0f4b476 184 // sensor in a certain orientation.
mjr 104:6e06e0f4b476 185 virtual int getOrientation() const { return 1; }
mjr 104:6e06e0f4b476 186
mjr 104:6e06e0f4b476 187 // the hardware sensor interface
mjr 100:1ff35c07217c 188 PlungerSensorImageInterfaceTCD1103<invertedLogicGates> sensor;
mjr 100:1ff35c07217c 189 };