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

/media/uploads/mjr/pinscape_no_background_small_L7Miwr6.jpg

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.

TLC5940/TLC5940.h@33:d832bcab089e, 2015-10-21 (annotated)

Committer:
mjr
Date:
Wed Oct 21 21:53:07 2015 +0000
Revision:
33:d832bcab089e
Parent:
30:6e9902f06f48
Child:
38:091e511ce8a0
With expansion board 5940 "power enable" output; saving this feature, which is to be removed.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 26:cb71c4af2912 1 // Pinscape Controller TLC5940 interface
mjr 26:cb71c4af2912 2 //
mjr 26:cb71c4af2912 3 // Based on Spencer Davis's mbed TLC5940 library. Adapted for the
mjr 26:cb71c4af2912 4 // KL25Z, and simplified to just the functions needed for this
mjr 26:cb71c4af2912 5 // application. In particular, this version doesn't include support
mjr 26:cb71c4af2912 6 // for dot correction programming or status input. This version also
mjr 26:cb71c4af2912 7 // uses a different approach for sending the grayscale data updates,
mjr 26:cb71c4af2912 8 // sending updates during the blanking interval rather than overlapping
mjr 26:cb71c4af2912 9 // them with the PWM cycle. This results in very slightly longer
mjr 26:cb71c4af2912 10 // blanking intervals when updates are pending, effectively reducing
mjr 26:cb71c4af2912 11 // the PWM "on" duty cycle (and thus the output brightness) by about
mjr 26:cb71c4af2912 12 // 0.3%. This shouldn't be perceptible to users, so it's a small
mjr 26:cb71c4af2912 13 // trade-off for the advantage gained, which is much better signal
mjr 26:cb71c4af2912 14 // stability when using multiple TLC5940s daisy-chained together.
mjr 26:cb71c4af2912 15 // I saw a lot of instability when using the overlapped approach,
mjr 26:cb71c4af2912 16 // which seems to be eliminated entirely when sending updates during
mjr 26:cb71c4af2912 17 // the blanking interval.
mjr 26:cb71c4af2912 18
mjr 26:cb71c4af2912 19
mjr 26:cb71c4af2912 20 #ifndef TLC5940_H
mjr 26:cb71c4af2912 21 #define TLC5940_H
mjr 26:cb71c4af2912 22
mjr 33:d832bcab089e 23 // Should we do the grayscale update within the blanking interval?
mjr 33:d832bcab089e 24 // If this is set to 1, we'll send grayscale data during the blanking
mjr 33:d832bcab089e 25 // interval; if 0, we'll send grayscale during the PWM cycle.
mjr 33:d832bcab089e 26 // Mode 0 is the *intended* way of using these chips, but mode 1
mjr 33:d832bcab089e 27 // produces a more stable signal in my test setup.
mjr 33:d832bcab089e 28 //
mjr 33:d832bcab089e 29 // In my breadboard testing, using the standard data-during-PWM
mjr 33:d832bcab089e 30 // mode causes some amount of signal instability with multiple
mjr 33:d832bcab089e 31 // daisy-chained TLC5940's. It appears that there's some signal
mjr 33:d832bcab089e 32 // interference (maybe RF or electrical ringing in the wires) that
mjr 33:d832bcab089e 33 // can make the bit data and/or clock prone to noise that causes
mjr 33:d832bcab089e 34 // random bits to propagate down the daisy chain. This happens
mjr 33:d832bcab089e 35 // frequently enough in my breadboard setup to be visible as
mjr 33:d832bcab089e 36 // regular flicker. Careful wiring, short wire runs, and decoupling
mjr 33:d832bcab089e 37 // capacitors noticeably improve it, but I haven't been able to
mjr 33:d832bcab089e 38 // eliminate it entirely in my test setup. Using the data-during-
mjr 33:d832bcab089e 39 // blanking mode, however, *does* eliminate it entirely.
mjr 33:d832bcab089e 40 //
mjr 33:d832bcab089e 41 // It clearly should be possible to eliminate the signal problems
mjr 33:d832bcab089e 42 // in a well-designed PCB layout, but for the time being, I'm
mjr 33:d832bcab089e 43 // making data-during-blanking the default, since it provides
mjr 33:d832bcab089e 44 // such a noticeable improvement in my test setup, and the cost
mjr 33:d832bcab089e 45 // is minimal. The cost is that it lengthens the blanking interval
mjr 33:d832bcab089e 46 // slightly. With four chips and the SPI clock at 28MHz, the
mjr 33:d832bcab089e 47 // full data update takes 27us; with the PWM clock at 500kHz, the
mjr 33:d832bcab089e 48 // grayscale cycle is 8192us. This means that the 27us data send
mjr 33:d832bcab089e 49 // keeps the BLANK asserted for an additional 0.3% of the cycle
mjr 33:d832bcab089e 50 // time, which in term reduces output brightness by the same amount.
mjr 33:d832bcab089e 51 // This brightness reduction isn't noticeable on its own, but it
mjr 33:d832bcab089e 52 // can be seen as a flicker on data cycles if we send data on
mjr 33:d832bcab089e 53 // some blanking cycles but not on others. To eliminate the
mjr 33:d832bcab089e 54 // flicker, the code sends a data update on *every* cycle when
mjr 33:d832bcab089e 55 // using this mode to ensure that the 0.3% brightness reduction
mjr 33:d832bcab089e 56 // is uniform across time.
mjr 33:d832bcab089e 57 //
mjr 33:d832bcab089e 58 // When using this code with TLC5940 chips on a PCB, I recommend
mjr 33:d832bcab089e 59 // doing a test: set this to 0, run the board, turn on all outputs
mjr 33:d832bcab089e 60 // (connected to LEDs), and observe the results. If you don't
mjr 33:d832bcab089e 61 // see any randomness or flicker in a minute or two of observation,
mjr 33:d832bcab089e 62 // you're getting a good clean signal throughout the daisy chain
mjr 33:d832bcab089e 63 // and don't need the workaround. If you do see any instability,
mjr 33:d832bcab089e 64 // set this back to 1.
mjr 33:d832bcab089e 65 #define DATA_UPDATE_INSIDE_BLANKING 1
mjr 33:d832bcab089e 66
mjr 26:cb71c4af2912 67 #include "mbed.h"
mjr 26:cb71c4af2912 68 #include "FastPWM.h"
mjr 30:6e9902f06f48 69 #include "SimpleDMA.h"
mjr 26:cb71c4af2912 70
mjr 26:cb71c4af2912 71 /**
mjr 26:cb71c4af2912 72 * SPI speed used by the mbed to communicate with the TLC5940
mjr 26:cb71c4af2912 73 * The TLC5940 supports up to 30Mhz. It's best to keep this as
mjr 33:d832bcab089e 74 * high as possible, since a higher SPI speed yields a faster
mjr 33:d832bcab089e 75 * grayscale data update. However, I've seen some slight
mjr 33:d832bcab089e 76 * instability in the signal in my breadboard setup using the
mjr 33:d832bcab089e 77 * full 30MHz, so I've reduced this slightly, which seems to
mjr 33:d832bcab089e 78 * yield a solid signal. The limit will vary according to how
mjr 33:d832bcab089e 79 * clean the signal path is to the chips; you can probably crank
mjr 33:d832bcab089e 80 * this up to full speed if you have a well-designed PCB, good
mjr 33:d832bcab089e 81 * decoupling capacitors near the 5940 VCC/GND pins, and short
mjr 33:d832bcab089e 82 * wires between the KL25Z and the PCB. A short, clean path to
mjr 33:d832bcab089e 83 * KL25Z ground seems especially important.
mjr 26:cb71c4af2912 84 *
mjr 26:cb71c4af2912 85 * The SPI clock must be fast enough that the data transmission
mjr 26:cb71c4af2912 86 * time for a full update is comfortably less than the blanking
mjr 26:cb71c4af2912 87 * cycle time. The grayscale refresh requires 192 bits per TLC5940
mjr 26:cb71c4af2912 88 * in the daisy chain, and each bit takes one SPI clock to send.
mjr 26:cb71c4af2912 89 * Our reference setup in the Pinscape controller allows for up to
mjr 26:cb71c4af2912 90 * 4 TLC5940s, so a full refresh cycle on a fully populated system
mjr 26:cb71c4af2912 91 * would be 768 SPI clocks. The blanking cycle is 4096 GSCLK cycles.
mjr 26:cb71c4af2912 92 *
mjr 26:cb71c4af2912 93 * t(blank) = 4096 * 1/GSCLK_SPEED
mjr 26:cb71c4af2912 94 * t(refresh) = 768 * 1/SPI_SPEED
mjr 26:cb71c4af2912 95 * Therefore: SPI_SPEED must be > 768/4096 * GSCLK_SPEED
mjr 26:cb71c4af2912 96 *
mjr 26:cb71c4af2912 97 * Since the SPI speed can be so high, and since we want to keep
mjr 26:cb71c4af2912 98 * the GSCLK speed relatively low, the constraint above simply
mjr 26:cb71c4af2912 99 * isn't a factor. E.g., at SPI=30MHz and GSCLK=500kHz,
mjr 26:cb71c4af2912 100 * t(blank) is 8192us and t(refresh) is 25us.
mjr 26:cb71c4af2912 101 */
mjr 33:d832bcab089e 102 #define SPI_SPEED 2800000
mjr 26:cb71c4af2912 103
mjr 26:cb71c4af2912 104 /**
mjr 26:cb71c4af2912 105 * The rate at which the GSCLK pin is pulsed. This also controls
mjr 26:cb71c4af2912 106 * how often the reset function is called. The reset function call
mjr 26:cb71c4af2912 107 * rate is (1/GSCLK_SPEED) * 4096. The maximum reliable rate is
mjr 26:cb71c4af2912 108 * around 32Mhz. It's best to keep this rate as low as possible:
mjr 26:cb71c4af2912 109 * the higher the rate, the higher the refresh() call frequency,
mjr 26:cb71c4af2912 110 * so the higher the CPU load.
mjr 26:cb71c4af2912 111 *
mjr 26:cb71c4af2912 112 * The lower bound is probably dependent on the application. For
mjr 26:cb71c4af2912 113 * driving LEDs, the limiting factor is that lower rates will increase
mjr 26:cb71c4af2912 114 * visible flicker. 200 kHz seems to be a good lower bound for LEDs.
mjr 26:cb71c4af2912 115 * That provides about 48 cycles per second - that's about the same as
mjr 26:cb71c4af2912 116 * the 50 Hz A/C cycle rate in many countries, which was itself chosen
mjr 26:cb71c4af2912 117 * so that incandescent lights don't flicker. (This rate is a function
mjr 26:cb71c4af2912 118 * of human eye physiology, which has its own refresh cycle of sorts
mjr 26:cb71c4af2912 119 * that runs at about 50 Hz. If you're designing an LED system for
mjr 26:cb71c4af2912 120 * viewing by cats or drosophila, you might want to look into your
mjr 26:cb71c4af2912 121 * target species' eye physiology, since the persistence of vision
mjr 26:cb71c4af2912 122 * rate varies quite a bit from species to species.) Flicker tends to
mjr 26:cb71c4af2912 123 * be more noticeable in LEDs than in incandescents, since LEDs don't
mjr 26:cb71c4af2912 124 * have the thermal inertia of incandescents, so we use a slightly
mjr 26:cb71c4af2912 125 * higher default here. 500 kHz = 122 full grayscale cycles per
mjr 26:cb71c4af2912 126 * second = 122 reset calls per second (call every 8ms).
mjr 26:cb71c4af2912 127 */
mjr 26:cb71c4af2912 128 #define GSCLK_SPEED 500000
mjr 26:cb71c4af2912 129
mjr 26:cb71c4af2912 130 /**
mjr 26:cb71c4af2912 131 * This class controls a TLC5940 PWM driver IC.
mjr 26:cb71c4af2912 132 *
mjr 26:cb71c4af2912 133 * Using the TLC5940 class to control an LED:
mjr 26:cb71c4af2912 134 * @code
mjr 26:cb71c4af2912 135 * #include "mbed.h"
mjr 26:cb71c4af2912 136 * #include "TLC5940.h"
mjr 26:cb71c4af2912 137 *
mjr 26:cb71c4af2912 138 * // Create the TLC5940 instance
mjr 26:cb71c4af2912 139 * TLC5940 tlc(p7, p5, p21, p9, p10, p11, p12, 1);
mjr 26:cb71c4af2912 140 *
mjr 26:cb71c4af2912 141 * int main()
mjr 26:cb71c4af2912 142 * {
mjr 26:cb71c4af2912 143 * // Enable the first LED
mjr 26:cb71c4af2912 144 * tlc.set(0, 0xfff);
mjr 26:cb71c4af2912 145 *
mjr 26:cb71c4af2912 146 * while(1)
mjr 26:cb71c4af2912 147 * {
mjr 26:cb71c4af2912 148 * }
mjr 26:cb71c4af2912 149 * }
mjr 26:cb71c4af2912 150 * @endcode
mjr 26:cb71c4af2912 151 */
mjr 26:cb71c4af2912 152 class TLC5940
mjr 26:cb71c4af2912 153 {
mjr 26:cb71c4af2912 154 public:
mjr 26:cb71c4af2912 155 /**
mjr 26:cb71c4af2912 156 * Set up the TLC5940
mjr 26:cb71c4af2912 157 * @param SCLK - The SCK pin of the SPI bus
mjr 26:cb71c4af2912 158 * @param MOSI - The MOSI pin of the SPI bus
mjr 26:cb71c4af2912 159 * @param GSCLK - The GSCLK pin of the TLC5940(s)
mjr 26:cb71c4af2912 160 * @param BLANK - The BLANK pin of the TLC5940(s)
mjr 26:cb71c4af2912 161 * @param XLAT - The XLAT pin of the TLC5940(s)
mjr 26:cb71c4af2912 162 * @param nchips - The number of TLC5940s (if you are daisy chaining)
mjr 26:cb71c4af2912 163 */
mjr 26:cb71c4af2912 164 TLC5940(PinName SCLK, PinName MOSI, PinName GSCLK, PinName BLANK, PinName XLAT, int nchips)
mjr 26:cb71c4af2912 165 : spi(MOSI, NC, SCLK),
mjr 26:cb71c4af2912 166 gsclk(GSCLK),
mjr 26:cb71c4af2912 167 blank(BLANK),
mjr 26:cb71c4af2912 168 xlat(XLAT),
mjr 33:d832bcab089e 169 nchips(nchips)
mjr 26:cb71c4af2912 170 {
mjr 33:d832bcab089e 171 // set XLAT to initially off
mjr 30:6e9902f06f48 172 xlat = 0;
mjr 33:d832bcab089e 173
mjr 33:d832bcab089e 174 // Assert BLANK while starting up, to keep the outputs turned off until
mjr 33:d832bcab089e 175 // everything is stable. This helps prevent spurious flashes during startup.
mjr 33:d832bcab089e 176 // (That's not particularly important for lights, but it matters more for
mjr 33:d832bcab089e 177 // tactile devices. It's a bit alarming to fire a replay knocker on every
mjr 33:d832bcab089e 178 // power-on, for example.)
mjr 30:6e9902f06f48 179 blank = 1;
mjr 30:6e9902f06f48 180
mjr 33:d832bcab089e 181 // allocate the grayscale buffer, and set all outputs to fully off
mjr 26:cb71c4af2912 182 gs = new unsigned short[nchips*16];
mjr 28:2097c6f8f2db 183 memset(gs, 0, nchips*16*sizeof(gs[0]));
mjr 26:cb71c4af2912 184
mjr 26:cb71c4af2912 185 // Configure SPI format and speed. Note that KL25Z ONLY supports 8-bit
mjr 26:cb71c4af2912 186 // mode. The TLC5940 nominally requires 12-bit data blocks for the
mjr 26:cb71c4af2912 187 // grayscale levels, but SPI is ultimately just a bit-level serial format,
mjr 26:cb71c4af2912 188 // so we can reformat the 12-bit blocks into 8-bit bytes to fit the
mjr 26:cb71c4af2912 189 // KL25Z's limits. This should work equally well on other microcontrollers
mjr 26:cb71c4af2912 190 // that are more flexible. The TLC5940 appears to require polarity/phase
mjr 26:cb71c4af2912 191 // format 0.
mjr 26:cb71c4af2912 192 spi.format(8, 0);
mjr 26:cb71c4af2912 193 spi.frequency(SPI_SPEED);
mjr 33:d832bcab089e 194
mjr 33:d832bcab089e 195 // Send out a full data set to the chips, to clear out any random
mjr 33:d832bcab089e 196 // startup data from the registers. Include some extra bits - there
mjr 33:d832bcab089e 197 // are some cases (such as after sending dot correct commands) where
mjr 33:d832bcab089e 198 // an extra bit per chip is required, and the initial state is
mjr 33:d832bcab089e 199 // somewhat unpredictable, so send extra just to make sure we cover
mjr 33:d832bcab089e 200 // all bases. This does no harm; extra bits just fall off the end of
mjr 33:d832bcab089e 201 // the daisy chain, and since we want all registers set to 0, we can
mjr 33:d832bcab089e 202 // send arbitrarily many extra 0's.
mjr 33:d832bcab089e 203 for (int i = 0 ; i < nchips*25 ; ++i)
mjr 33:d832bcab089e 204 spi.write(0);
mjr 33:d832bcab089e 205
mjr 33:d832bcab089e 206 // do an initial XLAT to latch all of these "0" values into the
mjr 33:d832bcab089e 207 // grayscale registers
mjr 33:d832bcab089e 208 xlat = 1;
mjr 33:d832bcab089e 209 xlat = 0;
mjr 29:582472d0bc57 210
mjr 30:6e9902f06f48 211 // Allocate a DMA buffer. The transfer on each cycle is 192 bits per
mjr 30:6e9902f06f48 212 // chip = 24 bytes per chip.
mjr 30:6e9902f06f48 213 dmabuf = new char[nchips*24];
mjr 26:cb71c4af2912 214
mjr 30:6e9902f06f48 215 // Set up the Simple DMA interface object. We use the DMA controller to
mjr 30:6e9902f06f48 216 // send grayscale data updates to the TLC5940 chips. This lets the CPU
mjr 30:6e9902f06f48 217 // keep running other tasks while we send gs updates, and importantly
mjr 30:6e9902f06f48 218 // allows our blanking interrupt handler return almost immediately.
mjr 30:6e9902f06f48 219 // The DMA transfer is from our internal DMA buffer to SPI0, which is
mjr 30:6e9902f06f48 220 // the SPI controller physically connected to the TLC5940s.
mjr 30:6e9902f06f48 221 sdma.source(dmabuf, 1);
mjr 30:6e9902f06f48 222 sdma.destination(&(SPI0->D), 0, 8);
mjr 30:6e9902f06f48 223 sdma.trigger(Trigger_SPI0_TX);
mjr 30:6e9902f06f48 224 sdma.attach(this, &TLC5940::dmaDone);
mjr 30:6e9902f06f48 225
mjr 30:6e9902f06f48 226 // Enable DMA on SPI0. SimpleDMA doesn't do this for us; we have to
mjr 30:6e9902f06f48 227 // do it explicitly. This is just a matter of setting bit 5 (TXDMAE)
mjr 30:6e9902f06f48 228 // in the SPI controllers Control Register 2 (C2).
mjr 30:6e9902f06f48 229 SPI0->C2 |= 0x20; // set bit 5 = 0x20 = TXDMAE in SPI0 control register 2
mjr 30:6e9902f06f48 230
mjr 30:6e9902f06f48 231 // Configure the GSCLK output's frequency
mjr 26:cb71c4af2912 232 gsclk.period(1.0/GSCLK_SPEED);
mjr 33:d832bcab089e 233
mjr 33:d832bcab089e 234 // mark that we need an initial update
mjr 33:d832bcab089e 235 newGSData = true;
mjr 33:d832bcab089e 236 needXlat = false;
mjr 30:6e9902f06f48 237 }
mjr 29:582472d0bc57 238
mjr 30:6e9902f06f48 239 // Start the clock running
mjr 29:582472d0bc57 240 void start()
mjr 29:582472d0bc57 241 {
mjr 26:cb71c4af2912 242 // Set up the first call to the reset function, which asserts BLANK to
mjr 26:cb71c4af2912 243 // end the PWM cycle and handles new grayscale data output and latching.
mjr 26:cb71c4af2912 244 // The original version of this library uses a timer to call reset
mjr 26:cb71c4af2912 245 // periodically, but that approach is somewhat problematic because the
mjr 26:cb71c4af2912 246 // reset function itself takes a small amount of time to run, so the
mjr 26:cb71c4af2912 247 // *actual* cycle is slightly longer than what we get from counting
mjr 26:cb71c4af2912 248 // GS clocks. Running reset on a timer therefore causes the calls to
mjr 26:cb71c4af2912 249 // slip out of phase with the actual full cycles, which causes
mjr 26:cb71c4af2912 250 // premature blanking that shows up as visible flicker. To get the
mjr 26:cb71c4af2912 251 // reset cycle to line up exactly with a full PWM cycle, it works
mjr 26:cb71c4af2912 252 // better to set up a new timer on each cycle, *after* we've finished
mjr 26:cb71c4af2912 253 // with the somewhat unpredictable overhead of the interrupt handler.
mjr 26:cb71c4af2912 254 // This ensures that we'll get much closer to exact alignment of the
mjr 26:cb71c4af2912 255 // cycle phase, and in any case the worst that happens is that some
mjr 26:cb71c4af2912 256 // cycles are very slightly too long or short (due to imperfections
mjr 26:cb71c4af2912 257 // in the timer clock vs the PWM clock that determines the GSCLCK
mjr 26:cb71c4af2912 258 // output to the TLC5940), which is far less noticeable than a
mjr 26:cb71c4af2912 259 // constantly rotating phase misalignment.
mjr 26:cb71c4af2912 260 reset_timer.attach(this, &TLC5940::reset, (1.0/GSCLK_SPEED)*4096.0);
mjr 26:cb71c4af2912 261 }
mjr 26:cb71c4af2912 262
mjr 26:cb71c4af2912 263 ~TLC5940()
mjr 26:cb71c4af2912 264 {
mjr 26:cb71c4af2912 265 delete [] gs;
mjr 30:6e9902f06f48 266 delete [] dmabuf;
mjr 26:cb71c4af2912 267 }
mjr 26:cb71c4af2912 268
mjr 26:cb71c4af2912 269 /**
mjr 26:cb71c4af2912 270 * Set the next chunk of grayscale data to be sent
mjr 26:cb71c4af2912 271 * @param data - Array of 16 bit shorts containing 16 12 bit grayscale data chunks per TLC5940
mjr 26:cb71c4af2912 272 * @note These must be in intervals of at least (1/GSCLK_SPEED) * 4096 to be sent
mjr 26:cb71c4af2912 273 */
mjr 26:cb71c4af2912 274 void set(int idx, unsigned short data)
mjr 26:cb71c4af2912 275 {
mjr 26:cb71c4af2912 276 // store the data, and flag the pending update for the interrupt handler to carry out
mjr 26:cb71c4af2912 277 gs[idx] = data;
mjr 30:6e9902f06f48 278 newGSData = true;
mjr 26:cb71c4af2912 279 }
mjr 26:cb71c4af2912 280
mjr 26:cb71c4af2912 281 private:
mjr 26:cb71c4af2912 282 // current level for each output
mjr 26:cb71c4af2912 283 unsigned short *gs;
mjr 26:cb71c4af2912 284
mjr 30:6e9902f06f48 285 // Simple DMA interface object
mjr 30:6e9902f06f48 286 SimpleDMA sdma;
mjr 30:6e9902f06f48 287
mjr 30:6e9902f06f48 288 // DMA transfer buffer. Each time we have data to transmit to the TLC5940 chips,
mjr 30:6e9902f06f48 289 // we format the data into this buffer exactly as it will go across the wire, then
mjr 30:6e9902f06f48 290 // hand the buffer to the DMA controller to move through the SPI port.
mjr 30:6e9902f06f48 291 char *dmabuf;
mjr 30:6e9902f06f48 292
mjr 26:cb71c4af2912 293 // SPI port - only MOSI and SCK are used
mjr 26:cb71c4af2912 294 SPI spi;
mjr 26:cb71c4af2912 295
mjr 26:cb71c4af2912 296 // use a PWM out for the grayscale clock - this provides a stable
mjr 26:cb71c4af2912 297 // square wave signal without consuming CPU
mjr 26:cb71c4af2912 298 FastPWM gsclk;
mjr 26:cb71c4af2912 299
mjr 26:cb71c4af2912 300 // Digital out pins used for the TLC5940
mjr 26:cb71c4af2912 301 DigitalOut blank;
mjr 26:cb71c4af2912 302 DigitalOut xlat;
mjr 26:cb71c4af2912 303
mjr 26:cb71c4af2912 304 // number of daisy-chained TLC5940s we're controlling
mjr 26:cb71c4af2912 305 int nchips;
mjr 26:cb71c4af2912 306
mjr 26:cb71c4af2912 307 // Timeout to end each PWM cycle. This is a one-shot timer that we reset
mjr 26:cb71c4af2912 308 // on each cycle.
mjr 26:cb71c4af2912 309 Timeout reset_timer;
mjr 26:cb71c4af2912 310
mjr 26:cb71c4af2912 311 // Has new GS/DC data been loaded?
mjr 26:cb71c4af2912 312 volatile bool newGSData;
mjr 33:d832bcab089e 313
mjr 33:d832bcab089e 314 // Do we need an XLAT signal on the next blanking interval?
mjr 33:d832bcab089e 315 volatile bool needXlat;
mjr 26:cb71c4af2912 316
mjr 26:cb71c4af2912 317 // Function to reset the display and send the next chunks of data
mjr 26:cb71c4af2912 318 void reset()
mjr 26:cb71c4af2912 319 {
mjr 30:6e9902f06f48 320 // start the blanking cycle
mjr 30:6e9902f06f48 321 startBlank();
mjr 33:d832bcab089e 322
mjr 33:d832bcab089e 323 #if DATA_UPDATE_INSIDE_BLANKING
mjr 33:d832bcab089e 324 // We're configured to send the new GS data entirely within
mjr 33:d832bcab089e 325 // the blanking interval. Start the DMA transfer now, and
mjr 33:d832bcab089e 326 // return without ending the blanking interval. The DMA
mjr 33:d832bcab089e 327 // completion interrupt handler will do that when the data
mjr 33:d832bcab089e 328 // update has completed.
mjr 33:d832bcab089e 329 //
mjr 33:d832bcab089e 330 // Note that we do the data update/ unconditionally in the
mjr 33:d832bcab089e 331 // send-during-blanking case, whether or not we have new GS
mjr 33:d832bcab089e 332 // data. This is because the update causes a 0.3% reduction
mjr 33:d832bcab089e 333 // in brightness because of the elongated BLANK interval.
mjr 33:d832bcab089e 334 // That would be visible as a flicker on each update if we
mjr 33:d832bcab089e 335 // did updates on some cycles and not others. By doing an
mjr 33:d832bcab089e 336 // update on every cycle, we make the brightness reduction
mjr 33:d832bcab089e 337 // uniform across time, which makes it less perceptible.
mjr 33:d832bcab089e 338 update();
mjr 33:d832bcab089e 339
mjr 33:d832bcab089e 340 #else // DATA_UPDATE_INSIDE_BLANKING
mjr 33:d832bcab089e 341
mjr 33:d832bcab089e 342 // end the blanking interval
mjr 33:d832bcab089e 343 endBlank();
mjr 33:d832bcab089e 344
mjr 33:d832bcab089e 345 // if we have pending grayscale data, start sending it
mjr 33:d832bcab089e 346 if (newGSData)
mjr 26:cb71c4af2912 347 update();
mjr 26:cb71c4af2912 348
mjr 33:d832bcab089e 349 #endif // DATA_UPDATE_INSIDE_BLANKING
mjr 30:6e9902f06f48 350 }
mjr 30:6e9902f06f48 351
mjr 30:6e9902f06f48 352 void startBlank()
mjr 30:6e9902f06f48 353 {
mjr 30:6e9902f06f48 354 // turn off the grayscale clock, and assert BLANK to end the grayscale cycle
mjr 30:6e9902f06f48 355 gsclk.write(0);
mjr 30:6e9902f06f48 356 blank = 1;
mjr 30:6e9902f06f48 357 }
mjr 26:cb71c4af2912 358
mjr 33:d832bcab089e 359 void endBlank()
mjr 30:6e9902f06f48 360 {
mjr 33:d832bcab089e 361 // if we've sent new grayscale data since the last blanking
mjr 33:d832bcab089e 362 // interval, latch it by asserting XLAT
mjr 33:d832bcab089e 363 if (needXlat)
mjr 30:6e9902f06f48 364 {
mjr 26:cb71c4af2912 365 // latch the new data while we're still blanked
mjr 26:cb71c4af2912 366 xlat = 1;
mjr 26:cb71c4af2912 367 xlat = 0;
mjr 33:d832bcab089e 368 needXlat = false;
mjr 26:cb71c4af2912 369 }
mjr 26:cb71c4af2912 370
mjr 26:cb71c4af2912 371 // end the blanking interval and restart the grayscale clock
mjr 26:cb71c4af2912 372 blank = 0;
mjr 26:cb71c4af2912 373 gsclk.write(.5);
mjr 26:cb71c4af2912 374
mjr 26:cb71c4af2912 375 // set up the next blanking interrupt
mjr 26:cb71c4af2912 376 reset_timer.attach(this, &TLC5940::reset, (1.0/GSCLK_SPEED)*4096.0);
mjr 26:cb71c4af2912 377 }
mjr 26:cb71c4af2912 378
mjr 26:cb71c4af2912 379 void update()
mjr 26:cb71c4af2912 380 {
mjr 30:6e9902f06f48 381 // Send new grayscale data to the TLC5940 chips.
mjr 30:6e9902f06f48 382 //
mjr 30:6e9902f06f48 383 // To do this, we set up our DMA buffer with the bytes formatted exactly
mjr 30:6e9902f06f48 384 // as they will go across the wire, then kick off the transfer request with
mjr 30:6e9902f06f48 385 // the DMA controller. We can then return from the interrupt and continue
mjr 30:6e9902f06f48 386 // with other tasks while the DMA hardware handles the transfer for us.
mjr 30:6e9902f06f48 387 // When the transfer is completed, the DMA controller will fire an
mjr 30:6e9902f06f48 388 // interrupt, which will call our interrupt handler, which will finish
mjr 30:6e9902f06f48 389 // the blanking cycle.
mjr 30:6e9902f06f48 390 //
mjr 30:6e9902f06f48 391 // The serial format orders the outputs from last to first (output #15 on
mjr 30:6e9902f06f48 392 // the last chip in the daisy-chain to output #0 on the first chip). For
mjr 30:6e9902f06f48 393 // each output, we send 12 bits containing the grayscale level (0 = fully
mjr 30:6e9902f06f48 394 // off, 0xFFF = fully on). Bit order is most significant bit first.
mjr 26:cb71c4af2912 395 //
mjr 26:cb71c4af2912 396 // The KL25Z SPI can only send in 8-bit increments, so we need to divvy up
mjr 26:cb71c4af2912 397 // the 12-bit outputs into 8-bit bytes. Each pair of 12-bit outputs adds up
mjr 26:cb71c4af2912 398 // to 24 bits, which divides evenly into 3 bytes, so send each pairs of
mjr 26:cb71c4af2912 399 // outputs as three bytes:
mjr 26:cb71c4af2912 400 //
mjr 26:cb71c4af2912 401 // [ element i+1 bits ] [ element i bits ]
mjr 26:cb71c4af2912 402 // 11 10 9 8 7 6 5 4 3 2 1 0 11 10 9 8 7 6 5 4 3 2 1 0
mjr 26:cb71c4af2912 403 // [ first byte ] [ second byte ] [ third byte ]
mjr 30:6e9902f06f48 404 for (int i = (16 * nchips) - 2, dst = 0 ; i >= 0 ; i -= 2)
mjr 26:cb71c4af2912 405 {
mjr 26:cb71c4af2912 406 // first byte - element i+1 bits 4-11
mjr 30:6e9902f06f48 407 dmabuf[dst++] = (((gs[i+1] & 0xFF0) >> 4) & 0xff);
mjr 26:cb71c4af2912 408
mjr 26:cb71c4af2912 409 // second byte - element i+1 bits 0-3, then element i bits 8-11
mjr 30:6e9902f06f48 410 dmabuf[dst++] = ((((gs[i+1] & 0x00F) << 4) | ((gs[i] & 0xF00) >> 8)) & 0xFF);
mjr 26:cb71c4af2912 411
mjr 26:cb71c4af2912 412 // third byte - element i bits 0-7
mjr 30:6e9902f06f48 413 dmabuf[dst++] = (gs[i] & 0x0FF);
mjr 26:cb71c4af2912 414 }
mjr 30:6e9902f06f48 415
mjr 30:6e9902f06f48 416 // Start the DMA transfer
mjr 30:6e9902f06f48 417 sdma.start(nchips*24);
mjr 33:d832bcab089e 418
mjr 33:d832bcab089e 419 // we've now cleared the new GS data
mjr 33:d832bcab089e 420 newGSData = false;
mjr 26:cb71c4af2912 421 }
mjr 30:6e9902f06f48 422
mjr 30:6e9902f06f48 423 // Interrupt handler for DMA completion. The DMA controller calls this
mjr 30:6e9902f06f48 424 // when it finishes with the transfer request we set up above. When the
mjr 30:6e9902f06f48 425 // transfer is done, we simply end the blanking cycle and start a new
mjr 30:6e9902f06f48 426 // grayscale cycle.
mjr 30:6e9902f06f48 427 void dmaDone()
mjr 30:6e9902f06f48 428 {
mjr 33:d832bcab089e 429 // mark that we need to assert XLAT to latch the new
mjr 33:d832bcab089e 430 // grayscale data during the next blanking interval
mjr 33:d832bcab089e 431 needXlat = true;
mjr 33:d832bcab089e 432
mjr 33:d832bcab089e 433 #if DATA_UPDATE_INSIDE_BLANKING
mjr 33:d832bcab089e 434 // we're doing the gs update within the blanking cycle, so end
mjr 33:d832bcab089e 435 // the blanking cycle now that the transfer has completed
mjr 33:d832bcab089e 436 endBlank();
mjr 33:d832bcab089e 437 #endif
mjr 30:6e9902f06f48 438 }
mjr 30:6e9902f06f48 439
mjr 26:cb71c4af2912 440 };
mjr 26:cb71c4af2912 441
mjr 26:cb71c4af2912 442 #endif