An I/O controller for virtual pinball machines: accelerometer nudge sensing, analog plunger input, button input encoding, LedWiz compatible output controls, and more.

Dependencies:   mbed FastIO FastPWM USBDevice

Fork of Pinscape_Controller by Mike R


This is Version 2 of the Pinscape Controller, an I/O controller for virtual pinball machines. (You can find the old version 1 software here.) Pinscape is software for the KL25Z that turns the board into a full-featured I/O controller for virtual pinball, with support for accelerometer-based nudging, a real plunger, button inputs, and feedback device control.

In case you haven't heard of the concept before, a "virtual pinball machine" is basically a video pinball simulator that's built into a real pinball machine body. A TV monitor goes in place of the pinball playfield, and a second TV goes in the backbox to serve as the "backglass" display. A third smaller monitor can serve as the "DMD" (the Dot Matrix Display used for scoring on newer machines), or you can even install a real pinball plasma DMD. A computer is hidden inside the cabinet, running pinball emulation software that displays a life-sized playfield on the main TV. The cabinet has all of the usual buttons, too, so it not only looks like the real thing, but plays like it too. That's a picture of my own machine to the right. On the outside, it's built exactly like a real arcade pinball machine, with the same overall dimensions and all of the standard pinball cabinet hardware.

A few small companies build and sell complete, finished virtual pinball machines, but I think it's more fun as a DIY project. If you have some basic wood-working skills and know your way around PCs, you can build one from scratch. The computer part is just an ordinary Windows PC, and all of the pinball emulation can be built out of free, open-source software. In that spirit, the Pinscape Controller is an open-source software/hardware project that offers a no-compromises, all-in-one control center for all of the unique input/output needs of a virtual pinball cabinet. If you've been thinking about building one of these, but you're not sure how to connect a plunger, flipper buttons, lights, nudge sensor, and whatever else you can think of, this project might be just what you're looking for.

You can find much more information about DIY Pin Cab building in general in the Virtual Cabinet Forum on Also visit my Pinscape Resources page for more about this project and other virtual pinball projects I'm working on.


  • Pinscape Release Builds: This page has download links for all of the Pinscape software. To get started, install and run the Pinscape Config Tool on your Windows computer. It will lead you through the steps for installing the Pinscape firmware on the KL25Z.
  • Config Tool Source Code. The complete C# source code for the config tool. You don't need this to run the tool, but it's available if you want to customize anything or see how it works inside.


The new Version 2 Build Guide is now complete! This new version aims to be a complete guide to building a virtual pinball machine, including not only the Pinscape elements but all of the basics, from sourcing parts to building all of the hardware.

You can also refer to the original Hardware Build Guide (PDF), but that's out of date now, since it refers to the old version 1 software, which was rather different (especially when it comes to configuration).

System Requirements

The new config tool requires a fairly up-to-date Microsoft .NET installation. If you use Windows Update to keep your system current, you should be fine. A modern version of Internet Explorer (IE) is required, even if you don't use it as your main browser, because the config tool uses some system components that Microsoft packages into the IE install set. I test with IE11, so that's known to work. IE8 doesn't work. IE9 and 10 are unknown at this point.

The Windows requirements are only for the config tool. The firmware doesn't care about anything on the Windows side, so if you can make do without the config tool, you can use almost any Windows setup.

Main Features

Plunger: The Pinscape Controller started out as a "mechanical plunger" controller: a device for attaching a real pinball plunger to the video game software so that you could launch the ball the natural way. This is still, of course, a central feature of the project. The software supports several types of sensors: a high-resolution optical sensor (which works by essentially taking pictures of the plunger as it moves); a slide potentionmeter (which determines the position via the changing electrical resistance in the pot); a quadrature sensor (which counts bars printed on a special guide rail that it moves along); and an IR distance sensor (which determines the position by sending pulses of light at the plunger and measuring the round-trip travel time). The Build Guide explains how to set up each type of sensor.

Nudging: The KL25Z (the little microcontroller that the software runs on) has a built-in accelerometer. The Pinscape software uses it to sense when you nudge the cabinet, and feeds the acceleration data to the pinball software on the PC. This turns physical nudges into virtual English on the ball. The accelerometer is quite sensitive and accurate, so we can measure the difference between little bumps and hard shoves, and everything in between. The result is natural and immersive.

Buttons: You can wire real pinball buttons to the KL25Z, and the software will translate the buttons into PC input. You have the option to map each button to a keyboard key or joystick button. You can wire up your flipper buttons, Magna Save buttons, Start button, coin slots, operator buttons, and whatever else you need.

Feedback devices: You can also attach "feedback devices" to the KL25Z. Feedback devices are things that create tactile, sound, and lighting effects in sync with the game action. The most popular PC pinball emulators know how to address a wide variety of these devices, and know how to match them to on-screen action in each virtual table. You just need an I/O controller that translates commands from the PC into electrical signals that turn the devices on and off. The Pinscape Controller can do that for you.

Expansion Boards

There are two main ways to run the Pinscape Controller: standalone, or using the "expansion boards".

In the basic standalone setup, you just need the KL25Z, plus whatever buttons, sensors, and feedback devices you want to attach to it. This mode lets you take advantage of everything the software can do, but for some features, you'll have to build some ad hoc external circuitry to interface external devices with the KL25Z. The Build Guide has detailed plans for exactly what you need to build.

The other option is the Pinscape Expansion Boards. The expansion boards are a companion project, which is also totally free and open-source, that provides Printed Circuit Board (PCB) layouts that are designed specifically to work with the Pinscape software. The PCB designs are in the widely used EAGLE format, which many PCB manufacturers can turn directly into physical boards for you. The expansion boards organize all of the external connections more neatly than on the standalone KL25Z, and they add all of the interface circuitry needed for all of the advanced software functions. The big thing they bring to the table is lots of high-power outputs. The boards provide a modular system that lets you add boards to add more outputs. If you opt for the basic core setup, you'll have enough outputs for all of the toys in a really well-equipped cabinet. If your ambitions go beyond merely well-equipped and run to the ridiculously extravagant, just add an extra board or two. The modular design also means that you can add to the system over time.

Expansion Board project page

Update notes

If you have a Pinscape V1 setup already installed, you should be able to switch to the new version pretty seamlessly. There are just a couple of things to be aware of.

First, the "configuration" procedure is completely different in the new version. Way better and way easier, but it's not what you're used to from V1. In V1, you had to edit the project source code and compile your own custom version of the program. No more! With V2, you simply install the standard, pre-compiled .bin file, and select options using the Pinscape Config Tool on Windows.

Second, if you're using the TSL1410R optical sensor for your plunger, there's a chance you'll need to boost your light source's brightness a little bit. The "shutter speed" is faster in this version, which means that it doesn't spend as much time collecting light per frame as before. The software actually does "auto exposure" adaptation on every frame, so the increased shutter speed really shouldn't bother it, but it does require a certain minimum level of contrast, which requires a certain minimal level of lighting. Check the plunger viewer in the setup tool if you have any problems; if the image looks totally dark, try increasing the light level to see if that helps.

New Features

V2 has numerous new features. Here are some of the highlights...

Dynamic configuration: as explained above, configuration is now handled through the Config Tool on Windows. It's no longer necessary to edit the source code or compile your own modified binary.

Improved plunger sensing: the software now reads the TSL1410R optical sensor about 15x faster than it did before. This allows reading the sensor at full resolution (400dpi), about 400 times per second. The faster frame rate makes a big difference in how accurately we can read the plunger position during the fast motion of a release, which allows for more precise position sensing and faster response. The differences aren't dramatic, since the sensing was already pretty good even with the slower V1 scan rate, but you might notice a little better precision in tricky skill shots.

Keyboard keys: button inputs can now be mapped to keyboard keys. The joystick button option is still available as well, of course. Keyboard keys have the advantage of being closer to universal for PC pinball software: some pinball software can be set up to take joystick input, but nearly all PC pinball emulators can take keyboard input, and nearly all of them use the same key mappings.

Local shift button: one physical button can be designed as the local shift button. This works like a Shift button on a keyboard, but with cabinet buttons. It allows each physical button on the cabinet to have two PC keys assigned, one normal and one shifted. Hold down the local shift button, then press another key, and the other key's shifted key mapping is sent to the PC. The shift button can have a regular key mapping of its own as well, so it can do double duty. The shift feature lets you access more functions without cluttering your cabinet with extra buttons. It's especially nice for less frequently used functions like adjusting the volume or activating night mode.

Night mode: the output controller has a new "night mode" option, which lets you turn off all of your noisy devices with a single button, switch, or PC command. You can designate individual ports as noisy or not. Night mode only disables the noisemakers, so you still get the benefit of your flashers, button lights, and other quiet devices. This lets you play late into the night without disturbing your housemates or neighbors.

Gamma correction: you can designate individual output ports for gamma correction. This adjusts the intensity level of an output to make it match the way the human eye perceives brightness, so that fades and color mixes look more natural in lighting devices. You can apply this to individual ports, so that it only affects ports that actually have lights of some kind attached.

IR Remote Control: the controller software can transmit and/or receive IR remote control commands if you attach appropriate parts (an IR LED to send, an IR sensor chip to receive). This can be used to turn on your TV(s) when the system powers on, if they don't turn on automatically, and for any other functions you can think of requiring IR send/receive capabilities. You can assign IR commands to cabinet buttons, so that pressing a button on your cabinet sends a remote control command from the attached IR LED, and you can have the controller generate virtual key presses on your PC in response to received IR commands. If you have the IR sensor attached, the system can use it to learn commands from your existing remotes.

Yet more USB fixes: I've been gradually finding and fixing USB bugs in the mbed library for months now. This version has all of the fixes of the last couple of releases, of course, plus some new ones. It also has a new "last resort" feature, since there always seems to be "just one more" USB bug. The last resort is that you can tell the device to automatically reboot itself if it loses the USB connection and can't restore it within a given time limit.

More Downloads

  • Custom VP builds: I created modified versions of Visual Pinball 9.9 and Physmod5 that you might want to use in combination with this controller. The modified versions have special handling for plunger calibration specific to the Pinscape Controller, as well as some enhancements to the nudge physics. If you're not using the plunger, you might still want it for the nudge improvements. The modified version also works with any other input controller, so you can get the enhanced nudging effects even if you're using a different plunger/nudge kit. The big change in the modified versions is a "filter" for accelerometer input that's designed to make the response to cabinet nudges more realistic. It also makes the response more subdued than in the standard VP, so it's not to everyone's taste. The downloads include both the updated executables and the source code changes, in case you want to merge the changes into your own custom version(s).

    Note! These features are now standard in the official VP releases, so you don't need my custom builds if you're using 9.9.1 or later and/or VP 10. I don't think there's any reason to use my versions instead of the latest official ones, and in fact I'd encourage you to use the official releases since they're more up to date, but I'm leaving my builds available just in case. In the official versions, look for the checkbox "Enable Nudge Filter" in the Keys preferences dialog. My custom versions don't include that checkbox; they just enable the filter unconditionally.
  • Output circuit shopping list: This is a saved shopping cart at with the parts needed to build one copy of the high-power output circuit for the LedWiz emulator feature, for use with the standalone KL25Z (that is, without the expansion boards). The quantities in the cart are for one output channel, so if you want N outputs, simply multiply the quantities by the N, with one exception: you only need one ULN2803 transistor array chip for each eight output circuits. If you're using the expansion boards, you won't need any of this, since the boards provide their own high-power outputs.
  • Cary Owens' optical sensor housing: A 3D-printable design for a housing/mounting bracket for the optical plunger sensor, designed by Cary Owens. This makes it easy to mount the sensor.
  • Lemming77's potentiometer mounting bracket and shooter rod connecter: Sketchup designs for 3D-printable parts for mounting a slide potentiometer as the plunger sensor. These were designed for a particular slide potentiometer that used to be available from an seller but is no longer listed. You can probably use this design as a starting point for other similar devices; just check the dimensions before committing the design to plastic.

Copyright and License

The Pinscape firmware is copyright 2014, 2021 by Michael J Roberts. It's released under an MIT open-source license. See License.

Warning to VirtuaPin Kit Owners

This software isn't designed as a replacement for the VirtuaPin plunger kit's firmware. If you bought the VirtuaPin kit, I recommend that you don't install this software. The VirtuaPin kit uses the same KL25Z microcontroller that Pinscape uses, but the rest of its hardware is different and incompatible. In particular, the Pinscape firmware doesn't include support for the IR proximity sensor used in the VirtuaPin plunger kit, so you won't be able to use your plunger device with the Pinscape firmware. In addition, the VirtuaPin setup uses a different set of GPIO pins for the button inputs from the Pinscape defaults, so if you do install the Pinscape firmware, you'll have to go into the Config Tool and reassign all of the buttons to match the VirtuaPin wiring.

Sat Apr 18 19:08:55 2020 +0000
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 // Plunger sensor implementation for rotary absolute encoders
mjr 100:1ff35c07217c 2 //
mjr 100:1ff35c07217c 3 // This implements the plunger interfaces for rotary absolute encoders. A
mjr 106:e9e3b46132c1 4 // rotary encoder measures the angle of a rotating shaft. An absolute encoder
mjr 106:e9e3b46132c1 5 // is one where the microcontroller can ask the sensor for its current angular
mjr 106:e9e3b46132c1 6 // position at any time. (As opposed to incremental encoders, which don't have
mjr 106:e9e3b46132c1 7 // any notion of their current position, but can only signal the host on each
mjr 106:e9e3b46132c1 8 // change in position.)
mjr 106:e9e3b46132c1 9 //
mjr 106:e9e3b46132c1 10 //
mjr 106:e9e3b46132c1 11 // For plunger sensing, we can convert the plunger's linear motion into angular
mjr 106:e9e3b46132c1 12 // motion using a mechanical link between the plunger rod and a rotating shaft
mjr 106:e9e3b46132c1 13 // positioned at a fixed point, somewhere nearby, but away from the plunger's
mjr 106:e9e3b46132c1 14 // axis of motion:
mjr 100:1ff35c07217c 15 //
mjr 100:1ff35c07217c 16 // =X=======================|=== <- plunger, X = connector attachment point
mjr 100:1ff35c07217c 17 // \
mjr 100:1ff35c07217c 18 // \ <- connector between plunger and shaft
mjr 100:1ff35c07217c 19 // \
mjr 100:1ff35c07217c 20 // * <- rotating shaft, at a fixed position
mjr 100:1ff35c07217c 21 //
mjr 100:1ff35c07217c 22 // As the plunger moves, the angle of the connector relative to the fixed
mjr 106:e9e3b46132c1 23 // shaft position changes in a predictable way, so we can infer the plunger's
mjr 106:e9e3b46132c1 24 // linear position at any given time by measuring the current rotational
mjr 106:e9e3b46132c1 25 // angle of the shaft.
mjr 100:1ff35c07217c 26 //
mjr 106:e9e3b46132c1 27 // The mechanical diagram above is, obviously, simplified for ASCII art's sake.
mjr 100:1ff35c07217c 28 // What's not shown is that the distance between the rotating shaft and the
mjr 100:1ff35c07217c 29 // "X" connection point on the plunger varies as the plunger moves, so the
mjr 100:1ff35c07217c 30 // mechanical linkage requires some way to accommodate that changing length.
mjr 106:e9e3b46132c1 31 // If the connector is a rigid rod, it has to be able to slide at one or
mjr 106:e9e3b46132c1 32 // the other connection points. Alternatively, rather than using a rigid
mjr 106:e9e3b46132c1 33 // linkage, we can use a spring or elastic band. We leave these details up
mjr 106:e9e3b46132c1 34 // to the mechanical design, since the software isn't affected by that, as
mjr 106:e9e3b46132c1 35 // long as the basic relationship between linear and angular motion as shown
mjr 106:e9e3b46132c1 36 // in the diagram is achieved.
mjr 100:1ff35c07217c 37 //
mjr 100:1ff35c07217c 38 //
mjr 100:1ff35c07217c 39 // Translating the angle to a linear position
mjr 100:1ff35c07217c 40 //
mjr 100:1ff35c07217c 41 // There are two complications to translating the angular reading back to
mjr 100:1ff35c07217c 42 // a linear plunger position.
mjr 100:1ff35c07217c 43 //
mjr 106:e9e3b46132c1 44 // 1. We have to consider the sensor's zero point to be arbitrary, because
mjr 106:e9e3b46132c1 45 // these sorts of sensors don't typically give the user a way to align the
mjr 106:e9e3b46132c1 46 // zero point at a desired physical position. The zero point will just be
mjr 106:e9e3b46132c1 47 // wherever it ends up after installation. The zero point could easily end
mjr 106:e9e3b46132c1 48 // up being somewhere in the middle of the plunger's travel range, which
mjr 106:e9e3b46132c1 49 // means that readings might "wrap" - e.g., we might see a series of readings
mjr 106:e9e3b46132c1 50 // when the plunger is moving in one direction like this: 4050, 4070, 4090,
mjr 106:e9e3b46132c1 51 // 14, 34 (note how we "wrapped" past some maximum angle reading for the
mjr 106:e9e3b46132c1 52 // sensor and went back to zero, then continued from there).
mjr 100:1ff35c07217c 53 //
mjr 100:1ff35c07217c 54 // To deal with this, we have to make a couple of assumptions:
mjr 100:1ff35c07217c 55 //
mjr 100:1ff35c07217c 56 // - The park position is at about 1/6 of the overall travel range
mjr 100:1ff35c07217c 57 // - The total angular travel range is less than one full revolution
mjr 100:1ff35c07217c 58 //
mjr 100:1ff35c07217c 59 // With those assumptions in hand, we can bias the raw readings to the
mjr 100:1ff35c07217c 60 // park position, and then take them modulo the raw scale. That will
mjr 100:1ff35c07217c 61 // ensure that readings wrap properly, regardless of where the raw zero
mjr 100:1ff35c07217c 62 // point lies.
mjr 100:1ff35c07217c 63 //
mjr 103:dec22cd65b2a 64 // 2. Going back to the original diagram, you can see that there's some
mjr 103:dec22cd65b2a 65 // trigonometry required to interpret the sensor's angular reading as a
mjr 103:dec22cd65b2a 66 // linear position on the plunger axis, which is of course what we need
mjr 103:dec22cd65b2a 67 // to report to the PC software.
mjr 103:dec22cd65b2a 68 //
mjr 103:dec22cd65b2a 69 // Let's use the vertical line between the plunger and the rotation point
mjr 103:dec22cd65b2a 70 // as the zero-degree reference point. To figure the plunger position,
mjr 100:1ff35c07217c 71 // we need to figure the difference between the raw angle reading and the
mjr 100:1ff35c07217c 72 // zero-degree point; call this theta. Let L be the position of the plunger
mjr 100:1ff35c07217c 73 // relative to the vertical reference point, let D be the length of the
mjr 100:1ff35c07217c 74 // vertical reference point line, and let H by the distance from the rotation
mjr 100:1ff35c07217c 75 // point to the plunger connection point. This is a right triangle with
mjr 100:1ff35c07217c 76 // hypotenuse H and sides L and D. D is a constant, because the rotation
mjr 100:1ff35c07217c 77 // point never moves, and the plunger never moves vertically. Thus we can
mjr 100:1ff35c07217c 78 // calculate D = H*cos(theta) and L = H*sin(theta). D is a constant, so
mjr 100:1ff35c07217c 79 // we can figure H = D/cos(theta) hence L = D*sin(theta)/cos(theta) or
mjr 100:1ff35c07217c 80 // D*tan(theta). If we wanted to know the true position in real-world
mjr 100:1ff35c07217c 81 // units, we'd have to know D, but only need arbitrary linear units, so
mjr 100:1ff35c07217c 82 // we can choose whatever value for D we find convenient: in particular,
mjr 100:1ff35c07217c 83 // a value that gives us the desired range and resolution for the final
mjr 100:1ff35c07217c 84 // result.
mjr 100:1ff35c07217c 85 //
mjr 103:dec22cd65b2a 86 // Note that the tangent diverges at +/-90 degrees, but that's okay,
mjr 103:dec22cd65b2a 87 // because the mechanical setup we've described is inherently constrained
mjr 103:dec22cd65b2a 88 // to stay well within those limits. This would even be true for an
mjr 103:dec22cd65b2a 89 // arbitrarily long range of motion along the travel axis, but we don't
mjr 103:dec22cd65b2a 90 // even have to worry about that since we have such a well-defined range
mjr 103:dec22cd65b2a 91 // of travel (of only about 3") to track.
mjr 100:1ff35c07217c 92 //
mjr 100:1ff35c07217c 93 // There's still one big piece missing here: we somehow have to know where
mjr 100:1ff35c07217c 94 // that vertical zero point lies. That's something we can only learn by
mjr 100:1ff35c07217c 95 // calibration. Unfortunately, we don't have a good way to detect this
mjr 100:1ff35c07217c 96 // directly. We *could* ask the user to look inside the cabinet and press
mjr 103:dec22cd65b2a 97 // a button when the needle is straight up, but that seems too cumbersome
mjr 103:dec22cd65b2a 98 // for the user, not to mention terribly imprecise. So we'll approach this
mjr 103:dec22cd65b2a 99 // from the other direction: we'll assume a particular placement of the
mjr 103:dec22cd65b2a 100 // rotation point relative to the travel range, and we'll provide
mjr 103:dec22cd65b2a 101 // installation instructions to achieve that assumed alignment.
mjr 100:1ff35c07217c 102 //
mjr 100:1ff35c07217c 103 // The full range we actually have after calibration consists of the park
mjr 100:1ff35c07217c 104 // position and the maximum retracted position. We could in principle also
mjr 100:1ff35c07217c 105 // calibrate the maximum forward position, but that can't be read as reliably
mjr 100:1ff35c07217c 106 // as the other two, because the barrel spring makes it difficult for the
mjr 100:1ff35c07217c 107 // user to be sure they've pushed it all the way forward. Since we can
mjr 100:1ff35c07217c 108 // extract the information we need from the park and max retract positions,
mjr 100:1ff35c07217c 109 // it's better to rely on those alone and not ask for information that the
mjr 100:1ff35c07217c 110 // user can't as easily provide. Given these positions, AND the assumption
mjr 100:1ff35c07217c 111 // that the rotation point is at the midpoint of the plunger travel range,
mjr 103:dec22cd65b2a 112 // we can do some grungy trig work to come up with a formula for the angle
mjr 103:dec22cd65b2a 113 // between the park position and the vertical:
mjr 100:1ff35c07217c 114 //
mjr 100:1ff35c07217c 115 // let C1 = 1 1/32" (distance from midpoint to park),
mjr 100:1ff35c07217c 116 // C2 = 1 17/32" (distance from midpoint to max retract),
mjr 100:1ff35c07217c 117 // C = C2/C1 = 1.48484849,
mjr 100:1ff35c07217c 118 // alpha = angle from park to vertical,
mjr 100:1ff35c07217c 119 // beta = angle from max retract to vertical
mjr 100:1ff35c07217c 120 // theta = alpha + beta = angle from park to max retract, known from calibration,
mjr 100:1ff35c07217c 121 // T = tan(theta);
mjr 100:1ff35c07217c 122 //
mjr 100:1ff35c07217c 123 // then
mjr 100:1ff35c07217c 124 // alpha = atan(sqrt(4*T*T*C + C^2 + 2*C + 1) - C - 1)/(2*T*C))
mjr 100:1ff35c07217c 125 //
mjr 103:dec22cd65b2a 126 // Did I mention this was grungy? At any rate, everything going into that
mjr 103:dec22cd65b2a 127 // last equation is either constant or known from the calibration, so we
mjr 103:dec22cd65b2a 128 // can pre-compute alpha and store it after each calibration operation.
mjr 103:dec22cd65b2a 129 // And once we've computed alpha, we can easily translate an angle reading
mjr 103:dec22cd65b2a 130 // from the sensor to an angle relative to the vertical, which we can plug
mjr 103:dec22cd65b2a 131 // into D*tan(angle) to convert to a linear position on the plunger axis.
mjr 103:dec22cd65b2a 132 //
mjr 103:dec22cd65b2a 133 // The final step is to scale that linear position into joystick reporting
mjr 103:dec22cd65b2a 134 // units. Those units are arbitrary, so we don't have to relate this to any
mjr 103:dec22cd65b2a 135 // real-world lengths. We can simply figure a scaling factor that maps the
mjr 103:dec22cd65b2a 136 // physical range to map to roughly the full range of the joystick units.
mjr 100:1ff35c07217c 137 //
mjr 100:1ff35c07217c 138 // If you're wondering how we derived that ugly formula, read on. Start
mjr 100:1ff35c07217c 139 // with the basic relationships D*tan(alpha) = C1 and D*tan(beta) = C2.
mjr 100:1ff35c07217c 140 // This lets us write tan(beta) in terms of tan(alpha) as
mjr 100:1ff35c07217c 141 // C2/C1*tan(alpha) = C*tan(alpha). We can combine this with an identity
mjr 100:1ff35c07217c 142 // for the tan of a sum of angles:
mjr 100:1ff35c07217c 143 //
mjr 100:1ff35c07217c 144 // tan(alpha + beta) = (tan(alpha) + tan(beta))/(1 - tan(alpha)*tan(beta))
mjr 100:1ff35c07217c 145 //
mjr 100:1ff35c07217c 146 // to obtain:
mjr 100:1ff35c07217c 147 //
mjr 100:1ff35c07217c 148 // tan(theta) = tan(alpha + beta) = (1 + C*tan(alpha))/(1 - C*tan^2(alpha))
mjr 100:1ff35c07217c 149 //
mjr 100:1ff35c07217c 150 // Everything here except alpha is known, so we now have a quadratic equation
mjr 100:1ff35c07217c 151 // for tan(alpha). We can solve that by cranking through the normal algorithm
mjr 100:1ff35c07217c 152 // for solving a quadratic equation, arriving at the solution above.
mjr 100:1ff35c07217c 153 //
mjr 100:1ff35c07217c 154 //
mjr 100:1ff35c07217c 155 // Choosing an install position
mjr 100:1ff35c07217c 156 //
mjr 100:1ff35c07217c 157 // There are two competing factors in choosing the optimal "D". On the one
mjr 100:1ff35c07217c 158 // hand, you'd like D to be as large as possible, to maximum linearity of the
mjr 100:1ff35c07217c 159 // tan function used to translate angle to linear position. Higher linearity
mjr 100:1ff35c07217c 160 // gives us greater immunity to variations in the precise centering of the
mjr 103:dec22cd65b2a 161 // rotation axis in the plunger travel range. tan() is pretty linear (that
mjr 103:dec22cd65b2a 162 // is, tan(theta) is approximately proportional to theta) for small theta,
mjr 103:dec22cd65b2a 163 // within about +/- 30 degrees. On the other hand, you'd like D to be as
mjr 103:dec22cd65b2a 164 // small as possible so that we get the largest overall angle range. Our
mjr 103:dec22cd65b2a 165 // sensor has a fixed angular resolution, so the more of the overall circle
mjr 103:dec22cd65b2a 166 // we use, the more sensor increments we have over the range, and thus the
mjr 103:dec22cd65b2a 167 // better effective linear resolution.
mjr 100:1ff35c07217c 168 //
mjr 100:1ff35c07217c 169 // Let's do some calculations for various "D" values (vertical distance
mjr 103:dec22cd65b2a 170 // between rotation point and plunger rod). We'll base our calculations
mjr 103:dec22cd65b2a 171 // on the AEAT-6012 sensor's 12-bit angular resolution.
mjr 100:1ff35c07217c 172 //
mjr 100:1ff35c07217c 173 // D theta(max) eff dpi theta(park)
mjr 100:1ff35c07217c 174 // -----------------------------------------------
mjr 100:1ff35c07217c 175 // 1 17/32" 45 deg 341 34 deg
mjr 100:1ff35c07217c 176 // 2" 37 deg 280 27 deg
mjr 100:1ff35c07217c 177 // 2 21/32" 30 deg 228 21 deg
mjr 100:1ff35c07217c 178 // 3 1/4" 25 deg 190 17 deg
mjr 100:1ff35c07217c 179 // 4 3/16" 20 deg 152 14 deg
mjr 100:1ff35c07217c 180 //
mjr 100:1ff35c07217c 181 // I'd consider 50 dpi to be the minimum for acceptable performance, 100 dpi
mjr 100:1ff35c07217c 182 // to be excellent, and anything above 300 dpi to be diminishing returns. So
mjr 100:1ff35c07217c 183 // for a 12-bit sensor, 2" looks like the sweet spot. It doesn't take us far
mjr 100:1ff35c07217c 184 // outside of the +/-30 deg zone of tan() linearity, and it achieves almost
mjr 100:1ff35c07217c 185 // 300 dpi of effective linear resolution. I'd stop there are not try to
mjr 100:1ff35c07217c 186 // push the angular resolution higher with a shorter D; with the 45 deg
mjr 100:1ff35c07217c 187 // theta(max) at D = 1-17/32", we'd get a lovely DPI level of 341, but at
mjr 100:1ff35c07217c 188 // the cost of getting pretty non-linear around the ends of the plunger
mjr 100:1ff35c07217c 189 // travel. Our math corrects for the non-linearity, but the more of that
mjr 100:1ff35c07217c 190 // correction we need, the more sensitive the whole contraption becomes to
mjr 100:1ff35c07217c 191 // getting the sensor positioning exactly right. The closer we can stay to
mjr 100:1ff35c07217c 192 // the linear approximation, the more tolerant we are of inexact sensor
mjr 100:1ff35c07217c 193 // positioning.
mjr 100:1ff35c07217c 194 //
mjr 100:1ff35c07217c 195 //
mjr 100:1ff35c07217c 196 // Supported sensors
mjr 100:1ff35c07217c 197 //
mjr 100:1ff35c07217c 198 // * AEAT-6012-A06. This is a magnetic absolute encoder with 12-bit
mjr 100:1ff35c07217c 199 // resolution. It linearly encodes one full (360 degree) rotation in
mjr 100:1ff35c07217c 200 // 4096 increments, so each increment represents 360/4096 = .088 degrees.
mjr 100:1ff35c07217c 201 //
mjr 100:1ff35c07217c 202 // The base class doesn't actually care much about the sensor type; all it
mjr 100:1ff35c07217c 203 // needs from the sensor is an angle reading represented on an arbitrary
mjr 100:1ff35c07217c 204 // linear scale. ("Linear" in the angle, so that one increment represents
mjr 100:1ff35c07217c 205 // a fixed number of degrees of arc. The full scale can represent one full
mjr 100:1ff35c07217c 206 // turn but doesn't have to, as long as the scale is linear over the range
mjr 100:1ff35c07217c 207 // covered.) To add new sensor types, you just need to add the code to
mjr 100:1ff35c07217c 208 // interface to the physical sensor and return its reading on an arbitrary
mjr 100:1ff35c07217c 209 // linear scale.
mjr 100:1ff35c07217c 210
mjr 100:1ff35c07217c 211 #ifndef _ROTARYSENSOR_H_
mjr 100:1ff35c07217c 212 #define _ROTARYSENSOR_H_
mjr 100:1ff35c07217c 213
mjr 100:1ff35c07217c 214 #include "FastInterruptIn.h"
mjr 100:1ff35c07217c 215 #include "AEAT6012.h"
mjr 100:1ff35c07217c 216
mjr 100:1ff35c07217c 217 // The conversion from raw sensor reading to linear position involves a
mjr 100:1ff35c07217c 218 // bunch of translations to different scales and unit systems. To help
mjr 100:1ff35c07217c 219 // keep things straight, let's give each scale a name:
mjr 100:1ff35c07217c 220 //
mjr 100:1ff35c07217c 221 // * "Raw" refers to the readings directly from the sensor. These are
mjr 103:dec22cd65b2a 222 // unsigned ints in the range 0..maxRawAngle, and represent angles in a
mjr 102:41d49e78c253 223 // unit system where one increment equals 360/maxRawAngle degrees. The
mjr 100:1ff35c07217c 224 // zero point is arbitrary, determined by the physical orientation
mjr 100:1ff35c07217c 225 // of the sensor.
mjr 100:1ff35c07217c 226 //
mjr 100:1ff35c07217c 227 // * "Biased" refers to angular units with a zero point equal to the
mjr 103:dec22cd65b2a 228 // park position. This uses the same unit size as the "raw" system, but
mjr 100:1ff35c07217c 229 // the zero point is adjusted so that 0 always means the park position.
mjr 100:1ff35c07217c 230 // Negative values are forward of the park position. This scale is
mjr 100:1ff35c07217c 231 // also adjusted for wrapping, by ensuring that the value lies in the
mjr 100:1ff35c07217c 232 // range -(maximum forward excursion) to +(scale max - max fwd excursion).
mjr 100:1ff35c07217c 233 // Any values below or above the range are bumped up or down (respectively)
mjr 100:1ff35c07217c 234 // to wrap them back into the range.
mjr 100:1ff35c07217c 235 //
mjr 100:1ff35c07217c 236 // * "Linear" refers to the final linear results, in joystick units, on
mjr 100:1ff35c07217c 237 // the abstract integer scale from 0..65535 used by the generic plunger
mjr 100:1ff35c07217c 238 // base class.
mjr 100:1ff35c07217c 239 //
mjr 100:1ff35c07217c 240 class PlungerSensorRotary: public PlungerSensor
mjr 100:1ff35c07217c 241 {
mjr 100:1ff35c07217c 242 public:
mjr 102:41d49e78c253 243 PlungerSensorRotary(int maxRawAngle, float radiansPerSensorUnit) :
mjr 100:1ff35c07217c 244 PlungerSensor(65535),
mjr 102:41d49e78c253 245 maxRawAngle(maxRawAngle),
mjr 100:1ff35c07217c 246 radiansPerSensorUnit(radiansPerSensorUnit)
mjr 100:1ff35c07217c 247 {
mjr 100:1ff35c07217c 248 // start our sample timer with an arbitrary zero point of now
mjr 100:1ff35c07217c 249 timer.start();
mjr 100:1ff35c07217c 250
mjr 100:1ff35c07217c 251 // clear the timing statistics
mjr 100:1ff35c07217c 252 nReads = 0;
mjr 100:1ff35c07217c 253 totalReadTime = 0;
mjr 100:1ff35c07217c 254
mjr 100:1ff35c07217c 255 // Pre-calculate the maximum forward excursion distance, in raw
mjr 100:1ff35c07217c 256 // units. For our reference mechanical setup with "D" in a likely
mjr 100:1ff35c07217c 257 // range, theta(max) is always about 10 degrees higher than
mjr 100:1ff35c07217c 258 // theta(park). 10 degrees is about 1/36 of the overall circle,
mjr 100:1ff35c07217c 259 // which is the same as 1/36 of the sensor scale. To be
mjr 100:1ff35c07217c 260 // conservative, allow for about 3X that, so allow 1/12 of scale
mjr 100:1ff35c07217c 261 // as the maximum forward excursion. For wrapping purposes, we'll
mjr 100:1ff35c07217c 262 // consider any reading outside of the range from -(excursion)
mjr 102:41d49e78c253 263 // to +(maxRawAngle - excursion) to be wrapped.
mjr 102:41d49e78c253 264 maxForwardExcursionRaw = maxRawAngle/12;
mjr 100:1ff35c07217c 265
mjr 100:1ff35c07217c 266 // reset the calibration counters
mjr 100:1ff35c07217c 267 biasedMinObserved = biasedMaxObserved = 0;
mjr 100:1ff35c07217c 268 }
mjr 100:1ff35c07217c 269
mjr 100:1ff35c07217c 270 // Restore the saved calibration at startup
mjr 100:1ff35c07217c 271 virtual void restoreCalibration(Config &cfg)
mjr 100:1ff35c07217c 272 {
mjr 100:1ff35c07217c 273 // only proceed if there's calibration data to retrieve
mjr 100:1ff35c07217c 274 if (
mjr 100:1ff35c07217c 275 {
mjr 100:1ff35c07217c 276 // we store the raw park angle in raw0
mjr 100:1ff35c07217c 277 rawParkAngle =;
mjr 100:1ff35c07217c 278
mjr 100:1ff35c07217c 279 // we store biased max angle in raw1
mjr 100:1ff35c07217c 280 biasedMax =;
mjr 100:1ff35c07217c 281 }
mjr 100:1ff35c07217c 282 else
mjr 100:1ff35c07217c 283 {
mjr 100:1ff35c07217c 284 // Use the current sensor reading as the initial guess at the
mjr 100:1ff35c07217c 285 // park position. The system is usually powered up with the
mjr 100:1ff35c07217c 286 // plunger at the neutral position, so this is a good guess in
mjr 100:1ff35c07217c 287 // most cases. If the plunger has been calibrated, we'll restore
mjr 100:1ff35c07217c 288 // the better guess when we restore the configuration later on in
mjr 100:1ff35c07217c 289 // the initialization process.
mjr 100:1ff35c07217c 290 rawParkAngle = 0;
mjr 100:1ff35c07217c 291 readSensor(rawParkAngle);
mjr 100:1ff35c07217c 292
mjr 100:1ff35c07217c 293 // Set an initial wild guess at a range equal to +/-35 degrees.
mjr 100:1ff35c07217c 294 // Note that this is in the "biased" coordinate system - raw
mjr 100:1ff35c07217c 295 // units, but relative to the park angle. The park angle is
mjr 102:41d49e78c253 296 // about -25 degrees in this setup.
mjr 102:41d49e78c253 297 biasedMax = (35 + 25) * maxRawAngle/360;
mjr 100:1ff35c07217c 298 }
mjr 100:1ff35c07217c 299
mjr 100:1ff35c07217c 300 // recalculate the vertical angle
mjr 100:1ff35c07217c 301 updateAlpha();
mjr 100:1ff35c07217c 302 }
mjr 100:1ff35c07217c 303
mjr 100:1ff35c07217c 304 // Begin calibration
mjr 100:1ff35c07217c 305 virtual void beginCalibration(Config &)
mjr 100:1ff35c07217c 306 {
mjr 100:1ff35c07217c 307 // Calibration starts out with the plunger at the park position, so
mjr 100:1ff35c07217c 308 // we can take the current sensor reading to be the park position.
mjr 100:1ff35c07217c 309 rawParkAngle = 0;
mjr 100:1ff35c07217c 310 readSensor(rawParkAngle);
mjr 100:1ff35c07217c 311
mjr 100:1ff35c07217c 312 // Reset the observed calibration counters
mjr 100:1ff35c07217c 313 biasedMinObserved = biasedMaxObserved = 0;
mjr 100:1ff35c07217c 314 }
mjr 100:1ff35c07217c 315
mjr 100:1ff35c07217c 316 // End calibration
mjr 100:1ff35c07217c 317 virtual void endCalibration(Config &cfg)
mjr 100:1ff35c07217c 318 {
mjr 100:1ff35c07217c 319 // apply the observed maximum angle
mjr 100:1ff35c07217c 320 biasedMax = biasedMaxObserved;
mjr 100:1ff35c07217c 321
mjr 100:1ff35c07217c 322 // recalculate the vertical angle
mjr 100:1ff35c07217c 323 updateAlpha();
mjr 100:1ff35c07217c 324
mjr 100:1ff35c07217c 325 // save our raw configuration data
mjr 100:1ff35c07217c 326 = static_cast<uint16_t>(rawParkAngle);
mjr 100:1ff35c07217c 327 = static_cast<uint16_t>(biasedMax);
mjr 100:1ff35c07217c 328
mjr 100:1ff35c07217c 329 // Refigure the range for the generic code
mjr 100:1ff35c07217c 330 = biasedAngleToLinear(biasedMinObserved);
mjr 100:1ff35c07217c 331 = biasedAngleToLinear(biasedMaxObserved);
mjr 100:1ff35c07217c 332 = biasedAngleToLinear(0);
mjr 100:1ff35c07217c 333 }
mjr 100:1ff35c07217c 334
mjr 100:1ff35c07217c 335 // figure the average scan time in microseconds
mjr 100:1ff35c07217c 336 virtual uint32_t getAvgScanTime()
mjr 100:1ff35c07217c 337 {
mjr 100:1ff35c07217c 338 return nReads == 0 ? 0 : static_cast<uint32_t>(totalReadTime / nReads);
mjr 100:1ff35c07217c 339 }
mjr 100:1ff35c07217c 340
mjr 100:1ff35c07217c 341 // read the sensor
mjr 100:1ff35c07217c 342 virtual bool readRaw(PlungerReading &r)
mjr 100:1ff35c07217c 343 {
mjr 100:1ff35c07217c 344 // note the starting time for the reading
mjr 100:1ff35c07217c 345 uint32_t t0 = timer.read_us();
mjr 100:1ff35c07217c 346
mjr 100:1ff35c07217c 347 // read the angular position
mjr 100:1ff35c07217c 348 int angle;
mjr 100:1ff35c07217c 349 if (!readSensor(angle))
mjr 100:1ff35c07217c 350 return false;
mjr 102:41d49e78c253 351
mjr 100:1ff35c07217c 352 // Refigure the angle relative to the raw park position. This
mjr 100:1ff35c07217c 353 // is the "biased" angle.
mjr 100:1ff35c07217c 354 angle -= rawParkAngle;
mjr 100:1ff35c07217c 355
mjr 100:1ff35c07217c 356 // Adjust for wrapping.
mjr 100:1ff35c07217c 357 //
mjr 100:1ff35c07217c 358 // An angular sensor reports the position on a circular scale, for
mjr 100:1ff35c07217c 359 // obvious reasons, so there's some point along the circle where the
mjr 100:1ff35c07217c 360 // angle is zero. One tick before that point reads as the maximum
mjr 100:1ff35c07217c 361 // angle on the scale, so we say that the scale "wraps" at that point.
mjr 100:1ff35c07217c 362 //
mjr 100:1ff35c07217c 363 // To correct for this, we can look to the layout of the mechanical
mjr 100:1ff35c07217c 364 // setup to constrain the values. Consider anything below the maximum
mjr 100:1ff35c07217c 365 // forward exclusion to be wrapped on the low side, and consider
mjr 100:1ff35c07217c 366 // anything outside of the complementary range on the high side to
mjr 100:1ff35c07217c 367 // be wrapped on the high side.
mjr 102:41d49e78c253 368 if (angle < -maxForwardExcursionRaw)
mjr 102:41d49e78c253 369 angle += maxRawAngle;
mjr 102:41d49e78c253 370 else if (angle >= maxRawAngle - maxForwardExcursionRaw)
mjr 102:41d49e78c253 371 angle -= maxRawAngle;
mjr 100:1ff35c07217c 372
mjr 100:1ff35c07217c 373 // Note if this is the highest/lowest observed reading on the biased
mjr 100:1ff35c07217c 374 // scale since the last calibration started.
mjr 100:1ff35c07217c 375 if (angle > biasedMaxObserved)
mjr 100:1ff35c07217c 376 biasedMaxObserved = angle;
mjr 100:1ff35c07217c 377 if (angle < biasedMinObserved)
mjr 100:1ff35c07217c 378 biasedMinObserved = angle;
mjr 100:1ff35c07217c 379
mjr 100:1ff35c07217c 380 // figure the linear result
mjr 100:1ff35c07217c 381 r.pos = biasedAngleToLinear(angle);
mjr 102:41d49e78c253 382
mjr 100:1ff35c07217c 383 // Set the timestamp on the reading to right now
mjr 100:1ff35c07217c 384 uint32_t now = timer.read_us();
mjr 100:1ff35c07217c 385 r.t = now;
mjr 100:1ff35c07217c 386
mjr 100:1ff35c07217c 387 // count the read statistics
mjr 100:1ff35c07217c 388 totalReadTime += now - t0;
mjr 100:1ff35c07217c 389 nReads += 1;
mjr 100:1ff35c07217c 390
mjr 100:1ff35c07217c 391 // success
mjr 100:1ff35c07217c 392 return true;
mjr 100:1ff35c07217c 393 }
mjr 100:1ff35c07217c 394
mjr 100:1ff35c07217c 395 private:
mjr 100:1ff35c07217c 396 // Read the underlying sensor - implemented by the hardware-specific
mjr 100:1ff35c07217c 397 // subclasses. Returns true on success, false if the sensor can't
mjr 100:1ff35c07217c 398 // be read. The angle is returned in raw sensor units.
mjr 100:1ff35c07217c 399 virtual bool readSensor(int &angle) = 0;
mjr 100:1ff35c07217c 400
mjr 100:1ff35c07217c 401 // Convert a biased angle value to a linear reading
mjr 100:1ff35c07217c 402 int biasedAngleToLinear(int angle)
mjr 100:1ff35c07217c 403 {
mjr 100:1ff35c07217c 404 // Translate to an angle relative to the vertical, in sensor units
mjr 102:41d49e78c253 405 float theta = static_cast<float>(angle)*radiansPerSensorUnit - alpha;
mjr 100:1ff35c07217c 406
mjr 102:41d49e78c253 407 // Calculate the linear position relative to the vertical. Zero
mjr 102:41d49e78c253 408 // is right at the intersection of the vertical line from the
mjr 102:41d49e78c253 409 // sensor rotation center to the plunger axis; positive numbers
mjr 102:41d49e78c253 410 // are behind the vertical (more retracted).
mjr 102:41d49e78c253 411 int linearPos = static_cast<int>(tanf(theta) * linearScaleFactor);
mjr 100:1ff35c07217c 412
mjr 102:41d49e78c253 413 // Finally, figure the offset. The vertical is the halfway point
mjr 102:41d49e78c253 414 // of the plunger motion, so we want to put it at half of the raw
mjr 102:41d49e78c253 415 // scale of 0..65535.
mjr 102:41d49e78c253 416 return linearPos + 32767;
mjr 100:1ff35c07217c 417 }
mjr 100:1ff35c07217c 418
mjr 100:1ff35c07217c 419 // Update the estimation of the vertical angle, based on the angle
mjr 100:1ff35c07217c 420 // between the park position and maximum retraction point.
mjr 100:1ff35c07217c 421 void updateAlpha()
mjr 100:1ff35c07217c 422 {
mjr 100:1ff35c07217c 423 // See the comments at the top of the file for details on this
mjr 100:1ff35c07217c 424 // formula. This figures the angle between the park position
mjr 100:1ff35c07217c 425 // and the vertical by applying the known constraints of the
mjr 100:1ff35c07217c 426 // mechanical setup: the known length of a standard plunger,
mjr 100:1ff35c07217c 427 // and the requirement that the rotation axis be placed at
mjr 100:1ff35c07217c 428 // roughly the midpoint of the plunger travel.
mjr 100:1ff35c07217c 429 const float C = 1.4848489f; // 1-17/32" / 1-1/32"
mjr 102:41d49e78c253 430 float maxInRadians = static_cast<float>(biasedMax) * radiansPerSensorUnit;
mjr 102:41d49e78c253 431 float T = tanf(maxInRadians);
mjr 102:41d49e78c253 432 alpha = atanf((sqrtf(4*T*T*C + C*C + 2*C + 1) - C - 1)/(2*T*C));
mjr 102:41d49e78c253 433
mjr 102:41d49e78c253 434 // While we're at it, figure the linear conversion factor. Alpha
mjr 102:41d49e78c253 435 // represents the angle from the park position to the midpoint,
mjr 102:41d49e78c253 436 // which in the real world represents about 31/32", or just less
mjr 102:41d49e78c253 437 // then 1/3 of the overall travel. We want to normalize this to
mjr 102:41d49e78c253 438 // the corresponding fraction of our 0..65535 abstract linear unit
mjr 102:41d49e78c253 439 // system. To avoid overflow, normalize to a slightly smaller
mjr 102:41d49e78c253 440 // scale.
mjr 100:1ff35c07217c 441 const float safeMax = 60000.0f;
mjr 102:41d49e78c253 442 const float alphaInLinearUnits = safeMax * .316327f; // 31/22" / 3-1/16"
mjr 102:41d49e78c253 443 linearScaleFactor = static_cast<int>(alphaInLinearUnits / tanf(alpha));
mjr 100:1ff35c07217c 444 }
mjr 100:1ff35c07217c 445
mjr 100:1ff35c07217c 446 // Maximum raw angular reading from the sensor. The sensor's readings
mjr 102:41d49e78c253 447 // will always be on a scale from 0..maxRawAngle.
mjr 102:41d49e78c253 448 int maxRawAngle;
mjr 100:1ff35c07217c 449
mjr 100:1ff35c07217c 450 // Radians per sensor unit. This is a constant for the sensor.
mjr 100:1ff35c07217c 451 float radiansPerSensorUnit;
mjr 100:1ff35c07217c 452
mjr 100:1ff35c07217c 453 // Pre-calculated value of the maximum forward excursion, in raw units.
mjr 102:41d49e78c253 454 int maxForwardExcursionRaw;
mjr 100:1ff35c07217c 455
mjr 100:1ff35c07217c 456 // Raw reading at the park position. We use this to handle "wrapping",
mjr 100:1ff35c07217c 457 // if the sensor's raw zero reading position is within the plunger travel
mjr 100:1ff35c07217c 458 // range. All readings are taken to be within
mjr 100:1ff35c07217c 459 int rawParkAngle;
mjr 100:1ff35c07217c 460
mjr 100:1ff35c07217c 461 // Biased maximum angle. This is the angle at the maximum retracted
mjr 100:1ff35c07217c 462 // position, in biased units (sensor units, relative to the park angle).
mjr 100:1ff35c07217c 463 int biasedMax;
mjr 100:1ff35c07217c 464
mjr 100:1ff35c07217c 465 // Mininum and maximum angle observed since last calibration start, on
mjr 100:1ff35c07217c 466 // the biased scale
mjr 100:1ff35c07217c 467 int biasedMinObserved;
mjr 100:1ff35c07217c 468 int biasedMaxObserved;
mjr 100:1ff35c07217c 469
mjr 100:1ff35c07217c 470 // The "alpha" angle - the angle between the park position and the
mjr 100:1ff35c07217c 471 // vertical line between the rotation axis and the plunger. This is
mjr 102:41d49e78c253 472 // represented in radians.
mjr 102:41d49e78c253 473 float alpha;
mjr 100:1ff35c07217c 474
mjr 100:1ff35c07217c 475 // The linear scaling factor, applied in our trig calculation from
mjr 100:1ff35c07217c 476 // angle to linear position. This corresponds to the distance from
mjr 100:1ff35c07217c 477 // the rotation center to the plunger rod, but since the linear result
mjr 100:1ff35c07217c 478 // is in abstract joystick units, this distance is likewise in abstract
mjr 100:1ff35c07217c 479 // units. The value isn't chosen to correspond to any real-world
mjr 100:1ff35c07217c 480 // distance units, but rather to yield a joystick result that takes
mjr 100:1ff35c07217c 481 // advantage of most of the available axis range, to minimize rounding
mjr 100:1ff35c07217c 482 // errors when converting between scales.
mjr 100:1ff35c07217c 483 float linearScaleFactor;
mjr 100:1ff35c07217c 484
mjr 100:1ff35c07217c 485 // timer for input timestamps and read timing measurements
mjr 100:1ff35c07217c 486 Timer timer;
mjr 100:1ff35c07217c 487
mjr 100:1ff35c07217c 488 // read timing statistics
mjr 100:1ff35c07217c 489 uint64_t totalReadTime;
mjr 100:1ff35c07217c 490 uint64_t nReads;
mjr 100:1ff35c07217c 491
mjr 100:1ff35c07217c 492 // Keep track of when calibration is in progress. The calibration
mjr 100:1ff35c07217c 493 // procedure is usually handled by the generic main loop code, but
mjr 100:1ff35c07217c 494 // in this case, we have to keep track of some of the raw sensor
mjr 100:1ff35c07217c 495 // data during calibration for our own internal purposes.
mjr 100:1ff35c07217c 496 bool calibrating;
mjr 100:1ff35c07217c 497 };
mjr 100:1ff35c07217c 498
mjr 100:1ff35c07217c 499 // Specialization for the AEAT-601X sensors
mjr 100:1ff35c07217c 500 template<int nDataBits> class PlungerSensorAEAT601X : public PlungerSensorRotary
mjr 100:1ff35c07217c 501 {
mjr 100:1ff35c07217c 502 public:
mjr 100:1ff35c07217c 503 PlungerSensorAEAT601X(PinName csPin, PinName clkPin, PinName doPin) :
mjr 100:1ff35c07217c 504 PlungerSensorRotary((1 << nDataBits) - 1, 6.283185f/((1 << nDataBits) - 1)),
mjr 100:1ff35c07217c 505 aeat(csPin, clkPin, doPin)
mjr 100:1ff35c07217c 506 {
mjr 100:1ff35c07217c 507 // Make sure the sensor has had time to finish initializing.
mjr 100:1ff35c07217c 508 // Power-up time (tCF) from the data sheet is 20ms for the 12-bit
mjr 100:1ff35c07217c 509 // version, 50ms for the 10-bit version.
mjr 100:1ff35c07217c 510 wait_ms(nDataBits == 12 ? 20 :
mjr 100:1ff35c07217c 511 nDataBits == 10 ? 50 :
mjr 100:1ff35c07217c 512 50);
mjr 100:1ff35c07217c 513 }
mjr 100:1ff35c07217c 514
mjr 100:1ff35c07217c 515 // read the angle
mjr 100:1ff35c07217c 516 virtual bool readSensor(int &angle)
mjr 100:1ff35c07217c 517 {
mjr 100:1ff35c07217c 518 angle = aeat.readAngle();
mjr 100:1ff35c07217c 519 return true;
mjr 100:1ff35c07217c 520 }
mjr 100:1ff35c07217c 521
mjr 100:1ff35c07217c 522 protected:
mjr 100:1ff35c07217c 523 // physical sensor interface
mjr 100:1ff35c07217c 524 AEAT601X<nDataBits> aeat;
mjr 100:1ff35c07217c 525 };
mjr 100:1ff35c07217c 526
mjr 100:1ff35c07217c 527 #endif