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 mechanical plunger, button inputs, and feedback device control.

In case you haven't heard of the idea 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 show the backglass artwork. Some cabs also include a third monitor to simulate the DMD (Dot Matrix Display) used for scoring on 1990s machines, or even an original plasma DMD. A computer (usually a Windows PC) 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 trim hardware.

It's possible to buy a pre-built virtual pinball machine, but it also makes a great 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 potentiometer (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 KL25Z can only run one firmware program at a time, so if you install the Pinscape firmware on your KL25Z, it will replace and erase your existing VirtuaPin proprietary firmware. If you do this, the only way to restore your VirtuaPin firmware is to physically ship the KL25Z back to VirtuaPin and ask them to re-flash it. They don't allow you to do this at home, and they don't even allow you to back up your firmware, since they want to protect their proprietary software from copying. For all of these reasons, if you want to run the Pinscape software, I strongly recommend that you buy a "blank" retail KL25Z to use with Pinscape. They only cost about $15 and are available at several online retailers, including Amazon, Mouser, and eBay. The blank retail boards don't come with any proprietary firmware pre-installed, so installing Pinscape won't delete anything that you paid extra for.

With those warnings in mind, if you're absolutely sure that you don't mind permanently erasing your VirtuaPin firmware, it is at least possible to use Pinscape as a replacement for the VirtuaPin firmware. Pinscape uses the same button wiring conventions as the VirtuaPin setup, so you can keep your buttons (although you'll have to update the GPIO pin mappings in the Config Tool to match your physical wiring). As of the June, 2021 firmware, the Vishay VCNL4010 plunger sensor that comes with the VirtuaPin v3 plunger kit is supported, so you can also keep your plunger, if you have that chip. (You should check to be sure that's the sensor chip you have before committing to this route, if keeping the plunger sensor is important to you. The older VirtuaPin plunger kits came with different IR sensors that the Pinscape software doesn't handle.)

Committer:
mjr
Date:
Thu Nov 28 23:18:23 2019 +0000
Revision:
100:1ff35c07217c
Child:
101:755f44622abc
Added preliminary support for AEAT-6012 and TCD1103 sensors; use continuous averaging for pot sensor analog in; more AltAnalogIn options for timing and resolution

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 100:1ff35c07217c 1 // Toshiba TCD1103 linear CCD image sensor, 1x1500 pixels
mjr 100:1ff35c07217c 2 //
mjr 100:1ff35c07217c 3 // This sensor is conceptually similar to the TAOS TSL1410R (the original
mjr 100:1ff35c07217c 4 // Pinscape sensor!). Like the TSL1410R, it has a linear array of optical
mjr 100:1ff35c07217c 5 // sensor pixels that convert incident photons into electrical charge, an
mjr 100:1ff35c07217c 6 // internal shift register connected to the pixel file that acts as an
mjr 100:1ff35c07217c 7 // electronic shutter, and a serial interface that clocks the pixels out
mjr 100:1ff35c07217c 8 // to the host in analog voltage level format.
mjr 100:1ff35c07217c 9 //
mjr 100:1ff35c07217c 10 // Mechanically, this sensor has an entirely different size scale vs the
mjr 100:1ff35c07217c 11 // TSL1410R. The 1410R's sensor window is about the same size as a standard
mjr 100:1ff35c07217c 12 // plunger's travel range (about 80mm), so the mechanical setup we use with
mjr 100:1ff35c07217c 13 // sensor is to situate the sensor adjacent to the plunger, with the pixel
mjr 100:1ff35c07217c 14 // window aligned with the plunger's axis of motion, so that the plunger
mjr 100:1ff35c07217c 15 // casts a shadow on the sensor at 1:1 scale. The TCD1103, in contrast, is
mjr 100:1ff35c07217c 16 // a tiny little thing, with about an 8mm window. That means that we have
mjr 100:1ff35c07217c 17 // to reduce the plunger shadow image by about 10X to fit the sensor, so an
mjr 100:1ff35c07217c 18 // optical lens is required. This makes it more complicated to set up, but
mjr 100:1ff35c07217c 19 // it also adds the advantage of allowing us to focus the image, for a more
mjr 100:1ff35c07217c 20 // precise reading. The shadow in the lens-less 1410R setup is usually about
mjr 100:1ff35c07217c 21 // four of five pixels wide, so we lose a lot of the sensor's native
mjr 100:1ff35c07217c 22 // precision to the poor optics - we only get about 1/50" resolution as a
mjr 100:1ff35c07217c 23 // result. With a focusing lens, we could potentially get single-pixel
mjr 100:1ff35c07217c 24 // resolution, which would be about 1/500" resolution. The reality will
mjr 100:1ff35c07217c 25 // be somewhat lower, depending on how hard we want to work at the optics,
mjr 100:1ff35c07217c 26 // but it should be possible to do much better than the unfocused 1410R.
mjr 100:1ff35c07217c 27 //
mjr 100:1ff35c07217c 28 // The electronic interface to this sensor has some fairly tight timing
mjr 100:1ff35c07217c 29 // requirements, per the data sheet. The sensor requires the host to
mjr 100:1ff35c07217c 30 // provide a master clock that runs at 0.4 MHz to 4 MHz. The data sheet's
mjr 100:1ff35c07217c 31 // timing diagrams imply that the master clock runs continuously, although
mjr 100:1ff35c07217c 32 // it's probably like the 1410R, where the clock is only needed when you
mjr 100:1ff35c07217c 33 // want to run the shift register and can be stopped at other times.
mjr 100:1ff35c07217c 34 //
mjr 100:1ff35c07217c 35 // As with the 1410R, we'll have to use DMA for the ADC transfers in order
mjr 100:1ff35c07217c 36 // to keep up with the high data rate without overloading the KL25Z CPU.
mjr 100:1ff35c07217c 37 // With the 1410R, we're able to use the ADC itself as the clock source,
mjr 100:1ff35c07217c 38 // by running the ADC in continous mode and using its "sample ready" signal
mjr 100:1ff35c07217c 39 // to trigger the DMA transfer. We used this to generate the external clock
mjr 100:1ff35c07217c 40 // signal for the sensor by "linking" the ADC's DMA channel to another pair
mjr 100:1ff35c07217c 41 // of DMA channels that generated the clock up/down signal each time an ADC
mjr 100:1ff35c07217c 42 // sample completed. This strategy won't work with the Toshiba sensor,
mjr 100:1ff35c07217c 43 // though, because the Toshiba sensor's timing sequence requires *two* clock
mjr 100:1ff35c07217c 44 // pulses per pixel. I can't come up with a way to accomplish that with the
mjr 100:1ff35c07217c 45 // linked-DMA approach. (I've tried!)
mjr 100:1ff35c07217c 46 //
mjr 100:1ff35c07217c 47 // So instead, we'll have to generate a true clock signal for the sensor.
mjr 100:1ff35c07217c 48 // The obvious way to do this (and the only way, as far as I can come up with)
mjr 100:1ff35c07217c 49 // is to use a TPM channel - that is, a PWM output. TPM channels are designed
mjr 100:1ff35c07217c 50 // precisely for this kind of work, so this is the right approach in terms of
mjr 100:1ff35c07217c 51 // suitability, but it has the downside that TPM units are an extremely scarce
mjr 100:1ff35c07217c 52 // resource on the KL25Z. We only have three of them to work with. Luckily
mjr 100:1ff35c07217c 53 // the rest of the Pinscape software only requires two of them: one for the
mjr 100:1ff35c07217c 54 // IR transmitter (which uses a TPM channel to generate the 41-48 kHz carrier
mjr 100:1ff35c07217c 55 // wave used by nearly all consumer IR remotes), and one for the TLC5940
mjr 100:1ff35c07217c 56 // driver (which uses it to generate the grayscale clock signal). Note that
mjr 100:1ff35c07217c 57 // we also use PWM channels for feedback device output ports, but those don't
mjr 100:1ff35c07217c 58 // have any dependency on the TPM period - they'll work with whatever period
mjr 100:1ff35c07217c 59 // the underlying TPM is set to use. So the feedback output ports can all
mjr 100:1ff35c07217c 60 // happily use free channels on TPM units claimed by any of the dedicated
mjr 100:1ff35c07217c 61 // users (IR, TLC5940, and us).
mjr 100:1ff35c07217c 62 //
mjr 100:1ff35c07217c 63 // But what do we do about the 2:1 ratio between master clock pulses and ADC
mjr 100:1ff35c07217c 64 // samples? The "right" way would be to allocate a second TPM unit to
mjr 100:1ff35c07217c 65 // generate a second clock signal at half the frequency of the master clock,
mjr 100:1ff35c07217c 66 // and use that as the ADC trigger. But as we just said, we only have three
mjr 100:1ff35c07217c 67 // TPM units in the whole system, and two of them are already claimed for
mjr 100:1ff35c07217c 68 // other uses, so we only have one unit to use here.
mjr 100:1ff35c07217c 69 //
mjr 100:1ff35c07217c 70 // Fortunately, we can make do with one TPM unit, by taking advantage of a
mjr 100:1ff35c07217c 71 // feature/quirk of the KL25Z ADC. The quirk lets us take ADC samples at
mjr 100:1ff35c07217c 72 // exactly half of the master clock rate, in perfect sync. The trick is to
mjr 100:1ff35c07217c 73 // pick a combination of master clock rate and ADC sample mode such that the
mjr 100:1ff35c07217c 74 // ADC conversion time is *almost but not quite* twice as long as the master
mjr 100:1ff35c07217c 75 // clock rate. With that combination of timings, we can trigger the ADC
mjr 100:1ff35c07217c 76 // from the TPM, and we'll get an ADC sample on exactly every other tick of
mjr 100:1ff35c07217c 77 // the master clock. The reason this works is that the KL25Z ADC ignores
mjr 100:1ff35c07217c 78 // hardware triggers (the TPM trigger is a hardware trigger) that occur when
mjr 100:1ff35c07217c 79 // a conversion is already in progress. So if the ADC sampling time is more
mjr 100:1ff35c07217c 80 // than one master clock period, the ADC will always be busy one clock tick
mjr 100:1ff35c07217c 81 // after a sample starts, so it'll ignore that first clock tick. But as
mjr 100:1ff35c07217c 82 // long as the sampling time is less than *two* master clock periods, the
mjr 100:1ff35c07217c 83 // ADC will always be ready again on the second tick. So we'll get one ADC
mjr 100:1ff35c07217c 84 // sample for every two master clock ticks, exactly as we need.
mjr 100:1ff35c07217c 85 //
mjr 100:1ff35c07217c 86
mjr 100:1ff35c07217c 87 #include "config.h"
mjr 100:1ff35c07217c 88 #include "NewPwm.h"
mjr 100:1ff35c07217c 89 #include "AltAnalogIn.h"
mjr 100:1ff35c07217c 90 #include "SimpleDMA.h"
mjr 100:1ff35c07217c 91 #include "DMAChannels.h"
mjr 100:1ff35c07217c 92
mjr 100:1ff35c07217c 93
mjr 100:1ff35c07217c 94 // Logic Gate Inverters: if invertedLogicGates is true, it means that the
mjr 100:1ff35c07217c 95 // hardware is buffering all of the logic signals (fM, ICG, SH) through an
mjr 100:1ff35c07217c 96 // inverter. The data sheet recommends using a 74HC04 between the host MCU
mjr 100:1ff35c07217c 97 // and the chip logic gates because of the high capacitive load on some of
mjr 100:1ff35c07217c 98 // the gates (particularly SH, 150pF).
mjr 100:1ff35c07217c 99
mjr 100:1ff35c07217c 100 template<bool invertedLogicGates> class TCD1103
mjr 100:1ff35c07217c 101 {
mjr 100:1ff35c07217c 102 public:
mjr 100:1ff35c07217c 103 TCD1103(PinName fmPin, PinName osPin, PinName icgPin, PinName shPin) :
mjr 100:1ff35c07217c 104 fm(fmPin, invertedLogicGates),
mjr 100:1ff35c07217c 105 os(osPin, false, 6, 1), // single sample, 6-cycle long sampling mode, no averaging
mjr 100:1ff35c07217c 106 icg(icgPin),
mjr 100:1ff35c07217c 107 sh(shPin),
mjr 100:1ff35c07217c 108 os_dma(DMAch_TDC_ADC)
mjr 100:1ff35c07217c 109 {
mjr 100:1ff35c07217c 110 // Calibrate the ADC for best accuracy
mjr 100:1ff35c07217c 111 os.calibrate();
mjr 100:1ff35c07217c 112
mjr 100:1ff35c07217c 113 // Idle conditions: SH low, ICG high.
mjr 100:1ff35c07217c 114 sh = logicLow;
mjr 100:1ff35c07217c 115 icg = logicHigh;
mjr 100:1ff35c07217c 116
mjr 100:1ff35c07217c 117 // ADC sample conversion time. This must be calculated based on the
mjr 100:1ff35c07217c 118 // combination of parameters selected for the os() initializer above.
mjr 100:1ff35c07217c 119 // See the KL25 Sub-Family Reference Manual, section 28.4.45, for the
mjr 100:1ff35c07217c 120 // formula.
mjr 100:1ff35c07217c 121 const float ADC_TIME = 2.2083333e-6f; // 6-cycle long sampling, no averaging
mjr 100:1ff35c07217c 122
mjr 100:1ff35c07217c 123 // Set the TPM cycle time to satisfy our timing constraints:
mjr 100:1ff35c07217c 124 //
mjr 100:1ff35c07217c 125 // Tm + epsilon1 < A < 2*Tm - epsilon2
mjr 100:1ff35c07217c 126 //
mjr 100:1ff35c07217c 127 // where A is the ADC conversion time and Tm is the master clock
mjr 100:1ff35c07217c 128 // period, and the epsilons are a margin of safety for any
mjr 100:1ff35c07217c 129 // non-deterministic component to the timing of A and Tm. The
mjr 100:1ff35c07217c 130 // epsilons could be zero if the timing of the ADC is perfectly
mjr 100:1ff35c07217c 131 // deterministic; this must be determined empirically.
mjr 100:1ff35c07217c 132 //
mjr 100:1ff35c07217c 133 // The most conservative solution would be to make epsilon as large
mjr 100:1ff35c07217c 134 // as possible, which means bisecting the time window by making
mjr 100:1ff35c07217c 135 // A = 1.5*T, or, equivalently, T = A/1.5 (the latter form being more
mjr 100:1ff35c07217c 136 // useful because T is the free variable here, as we can only control
mjr 100:1ff35c07217c 137 // A to the extent that we can choose the ADC parameters).
mjr 100:1ff35c07217c 138 //
mjr 100:1ff35c07217c 139 // But we'd also like to make T as short as possible while maintaining
mjr 100:1ff35c07217c 140 // reliable operation. Shorter T yields a higher frame rate, and we
mjr 100:1ff35c07217c 141 // want the frame rate to be as high as possible so that we can track
mjr 100:1ff35c07217c 142 // fast plunger motion accurately. Empirically, we can get reliable
mjr 100:1ff35c07217c 143 // results by using half of the ADC time plus a small buffer time.
mjr 100:1ff35c07217c 144 //
mjr 100:1ff35c07217c 145 fm.getUnit()->period(masterClockPeriod = ADC_TIME/2 + 0.1e-6f);
mjr 100:1ff35c07217c 146 printf("TCD1103 master clock period = %g\r\n", masterClockPeriod);
mjr 100:1ff35c07217c 147
mjr 100:1ff35c07217c 148 // Start the master clock running with a 50% duty cycle
mjr 100:1ff35c07217c 149 fm.write(0.5f);
mjr 100:1ff35c07217c 150
mjr 100:1ff35c07217c 151 // allocate our double pixel buffers
mjr 100:1ff35c07217c 152 pix1 = new uint8_t[nPixSensor*2];
mjr 100:1ff35c07217c 153 pix2 = pix1 + nPixSensor;
mjr 100:1ff35c07217c 154
mjr 100:1ff35c07217c 155 // put the first DMA transfer into the first buffer (pix1)
mjr 100:1ff35c07217c 156 pixDMA = 0;
mjr 100:1ff35c07217c 157 running = false;
mjr 100:1ff35c07217c 158
mjr 100:1ff35c07217c 159 // start the sample timer with an arbitrary epoch of "now"
mjr 100:1ff35c07217c 160 t.start();
mjr 100:1ff35c07217c 161
mjr 100:1ff35c07217c 162 // Set up the ADC transfer DMA channel. This channel transfers
mjr 100:1ff35c07217c 163 // the current analog sampling result from the ADC output register
mjr 100:1ff35c07217c 164 // to our pixel array.
mjr 100:1ff35c07217c 165 os.initDMA(&os_dma);
mjr 100:1ff35c07217c 166
mjr 100:1ff35c07217c 167 // Register an interrupt callback so that we're notified when
mjr 100:1ff35c07217c 168 // the last ADC transfer completes.
mjr 100:1ff35c07217c 169 os_dma.attach(this, &TCD1103::transferDone);
mjr 100:1ff35c07217c 170
mjr 100:1ff35c07217c 171 // Set up the ADC to trigger on the master clock's TPM channel
mjr 100:1ff35c07217c 172 os.setTriggerTPM(fm.getUnitNum());
mjr 100:1ff35c07217c 173
mjr 100:1ff35c07217c 174 // clear the timing statistics
mjr 100:1ff35c07217c 175 totalXferTime = 0.0;
mjr 100:1ff35c07217c 176 maxXferTime = 0;
mjr 100:1ff35c07217c 177 minXferTime = 0xffffffff;
mjr 100:1ff35c07217c 178 nRuns = 0;
mjr 100:1ff35c07217c 179
mjr 100:1ff35c07217c 180 // clear random power-up data by clocking through all pixels twice
mjr 100:1ff35c07217c 181 clear();
mjr 100:1ff35c07217c 182 clear();
mjr 100:1ff35c07217c 183 }
mjr 100:1ff35c07217c 184
mjr 100:1ff35c07217c 185 // logic gate levels, based on whether or not the logic gate connections
mjr 100:1ff35c07217c 186 // in the hardware are buffered through inverters
mjr 100:1ff35c07217c 187 static const int logicLow = invertedLogicGates ? 1 : 0;
mjr 100:1ff35c07217c 188 static const bool logicHigh = invertedLogicGates ? 0 : 1;
mjr 100:1ff35c07217c 189
mjr 100:1ff35c07217c 190 // ready to read
mjr 100:1ff35c07217c 191 bool ready() { return !running; }
mjr 100:1ff35c07217c 192
mjr 100:1ff35c07217c 193 // is the DMA busy?
mjr 100:1ff35c07217c 194 bool dmaBusy() { return running; }
mjr 100:1ff35c07217c 195
mjr 100:1ff35c07217c 196 // wait for the current DMA cycle to finish
mjr 100:1ff35c07217c 197 void wait() { while (running) ; }
mjr 100:1ff35c07217c 198
mjr 100:1ff35c07217c 199 // Get the stable pixel array. This is the image array from the
mjr 100:1ff35c07217c 200 // previous capture. It remains valid until the next startCapture()
mjr 100:1ff35c07217c 201 // call, at which point this buffer will be reused for the new capture.
mjr 100:1ff35c07217c 202 void getPix(uint8_t * &pix, uint32_t &t)
mjr 100:1ff35c07217c 203 {
mjr 100:1ff35c07217c 204 // return the pixel array that ISN'T assigned to the DMA
mjr 100:1ff35c07217c 205 if (pixDMA)
mjr 100:1ff35c07217c 206 {
mjr 100:1ff35c07217c 207 // DMA owns pix2, so the stable array is pix1
mjr 100:1ff35c07217c 208 pix = pix1;
mjr 100:1ff35c07217c 209 t = t1;
mjr 100:1ff35c07217c 210 }
mjr 100:1ff35c07217c 211 else
mjr 100:1ff35c07217c 212 {
mjr 100:1ff35c07217c 213 // DMA owns pix1, so the stable array is pix2
mjr 100:1ff35c07217c 214 pix = pix2;
mjr 100:1ff35c07217c 215 t = t2;
mjr 100:1ff35c07217c 216 }
mjr 100:1ff35c07217c 217
mjr 100:1ff35c07217c 218 // debugging - print out the pixel transfer time stats periodically
mjr 100:1ff35c07217c 219 static int n;
mjr 100:1ff35c07217c 220 ++n;
mjr 100:1ff35c07217c 221 if (n > 1000)
mjr 100:1ff35c07217c 222 {
mjr 100:1ff35c07217c 223 printf("TCD1103 scan last=%d, min=%d, max=%d (us)\r\n", dtPixXfer, minXferTime, maxXferTime);
mjr 100:1ff35c07217c 224 n = 0;
mjr 100:1ff35c07217c 225 }
mjr 100:1ff35c07217c 226 }
mjr 100:1ff35c07217c 227
mjr 100:1ff35c07217c 228 // wait for pixels to become ready
mjr 100:1ff35c07217c 229 void waitPix(uint8_t * &pix, uint32_t &t)
mjr 100:1ff35c07217c 230 {
mjr 100:1ff35c07217c 231 // wait for the current transfer to finish
mjr 100:1ff35c07217c 232 wait();
mjr 100:1ff35c07217c 233
mjr 100:1ff35c07217c 234 // Return the pixel array that IS assigned to DMA, since this
mjr 100:1ff35c07217c 235 // is the latest buffer filled. This buffer is stable, even
mjr 100:1ff35c07217c 236 // though it's assigned to DMA, because the last transfer is
mjr 100:1ff35c07217c 237 // already finished and thus DMA is no longer accessing the
mjr 100:1ff35c07217c 238 // buffer.
mjr 100:1ff35c07217c 239 if (pixDMA)
mjr 100:1ff35c07217c 240 {
mjr 100:1ff35c07217c 241 // DMA owns pix2
mjr 100:1ff35c07217c 242 pix = pix2;
mjr 100:1ff35c07217c 243 t = t2;
mjr 100:1ff35c07217c 244 }
mjr 100:1ff35c07217c 245 else
mjr 100:1ff35c07217c 246 {
mjr 100:1ff35c07217c 247 // DMA owns pix1
mjr 100:1ff35c07217c 248 pix = pix1;
mjr 100:1ff35c07217c 249 t = t1;
mjr 100:1ff35c07217c 250 }
mjr 100:1ff35c07217c 251 }
mjr 100:1ff35c07217c 252
mjr 100:1ff35c07217c 253 // Start an image capture from the sensor. Waits the previous
mjr 100:1ff35c07217c 254 // capture to finish if it's still running, then starts a new one
mjr 100:1ff35c07217c 255 // and returns immediately. The new capture proceeds autonomously
mjr 100:1ff35c07217c 256 // via the DMA hardware, so the caller can continue with other
mjr 100:1ff35c07217c 257 // processing during the capture.
mjr 100:1ff35c07217c 258 void startCapture(uint32_t minIntTime_us = 0)
mjr 100:1ff35c07217c 259 {
mjr 100:1ff35c07217c 260 IF_DIAG(uint32_t tDiag0 = mainLoopTimer.read_us();)
mjr 100:1ff35c07217c 261
mjr 100:1ff35c07217c 262 // wait for the last current capture to finish
mjr 100:1ff35c07217c 263 while (running) { }
mjr 100:1ff35c07217c 264
mjr 100:1ff35c07217c 265 // we're starting a new capture immediately
mjr 100:1ff35c07217c 266 running = true;
mjr 100:1ff35c07217c 267
mjr 100:1ff35c07217c 268 // collect timing diagnostics
mjr 100:1ff35c07217c 269 IF_DIAG(mainLoopIterCheckpt[8] += uint32_t(mainLoopTimer.read_us() - tDiag0);)
mjr 100:1ff35c07217c 270
mjr 100:1ff35c07217c 271 // If the elapsed time since the start of the last integration
mjr 100:1ff35c07217c 272 // hasn't reached the specified minimum yet, wait. This allows
mjr 100:1ff35c07217c 273 // the caller to control the integration time to optimize the
mjr 100:1ff35c07217c 274 // exposure level.
mjr 100:1ff35c07217c 275 uint32_t dt = uint32_t(t.read_us() - tInt);
mjr 100:1ff35c07217c 276 if (dt < minIntTime_us)
mjr 100:1ff35c07217c 277 {
mjr 100:1ff35c07217c 278 // we haven't reached the required minimum yet - wait for the
mjr 100:1ff35c07217c 279 // remaining interval
mjr 100:1ff35c07217c 280 wait_us(minIntTime_us - dt);
mjr 100:1ff35c07217c 281 }
mjr 100:1ff35c07217c 282
mjr 100:1ff35c07217c 283 // swap to the other DMA buffer for reading the new pixel samples
mjr 100:1ff35c07217c 284 pixDMA ^= 1;
mjr 100:1ff35c07217c 285
mjr 100:1ff35c07217c 286 // Set up the active pixel array as the destination buffer for
mjr 100:1ff35c07217c 287 // the ADC DMA channel.
mjr 100:1ff35c07217c 288 os_dma.destination(pixDMA ? pix2 : pix1, true);
mjr 100:1ff35c07217c 289
mjr 100:1ff35c07217c 290 // Start the read cycle by sending the ICG/SH pulse sequence
mjr 100:1ff35c07217c 291 uint32_t tNewInt = gen_SH_ICG_pulse(true);
mjr 100:1ff35c07217c 292
mjr 100:1ff35c07217c 293 // Set the timestamp for the current active buffer. The ICG/SH
mjr 100:1ff35c07217c 294 // gymnastics we just did transferred the CCD pixels into the sensor's
mjr 100:1ff35c07217c 295 // internal shift register and reset the pixels, starting a new
mjr 100:1ff35c07217c 296 // integration cycle. So the pixels we just shifted started
mjr 100:1ff35c07217c 297 // integrating the *last* time we did that, which we recorded as
mjr 100:1ff35c07217c 298 // tInt at the time. The image we're about to transfer therefore
mjr 100:1ff35c07217c 299 // represents the light collected between tInt and the SH pulse we
mjr 100:1ff35c07217c 300 // just did. The image covers a time range rather than a single
mjr 100:1ff35c07217c 301 // point in time, but we still have to give it a single timestamp.
mjr 100:1ff35c07217c 302 // Use the midpoint of the integration period.
mjr 100:1ff35c07217c 303 uint32_t tmid = (tNewInt + tInt) >> 1;
mjr 100:1ff35c07217c 304 if (pixDMA)
mjr 100:1ff35c07217c 305 t2 = tmid;
mjr 100:1ff35c07217c 306 else
mjr 100:1ff35c07217c 307 t1 = tmid;
mjr 100:1ff35c07217c 308
mjr 100:1ff35c07217c 309 // Record the start time of the currently active integration period
mjr 100:1ff35c07217c 310 tInt = tNewInt;
mjr 100:1ff35c07217c 311
mjr 100:1ff35c07217c 312 IF_DIAG(mainLoopIterCheckpt[9] += uint32_t(mainLoopTimer.read_us() - tDiag0);)
mjr 100:1ff35c07217c 313 }
mjr 100:1ff35c07217c 314
mjr 100:1ff35c07217c 315 // clear the sensor pixels
mjr 100:1ff35c07217c 316 void clear()
mjr 100:1ff35c07217c 317 {
mjr 100:1ff35c07217c 318 // make sure any DMA run is completed
mjr 100:1ff35c07217c 319 wait();
mjr 100:1ff35c07217c 320
mjr 100:1ff35c07217c 321 // send an SH/ICG pulse sequence to start an integration cycle
mjr 100:1ff35c07217c 322 // (without initiating a DMA transfer, as we just want to discard
mjr 100:1ff35c07217c 323 // the incoming samples for a "clear")
mjr 100:1ff35c07217c 324 tInt = gen_SH_ICG_pulse(false);
mjr 100:1ff35c07217c 325
mjr 100:1ff35c07217c 326 // wait for one full readout cycle, plus a little extra for padding
mjr 100:1ff35c07217c 327 ::wait(nPixSensor*masterClockPeriod*2 + 4.0e-6f);
mjr 100:1ff35c07217c 328 }
mjr 100:1ff35c07217c 329
mjr 100:1ff35c07217c 330 // figure the average scan time from the running totals
mjr 100:1ff35c07217c 331 uint32_t getAvgScanTime() { return static_cast<uint32_t>(totalXferTime / nRuns);}
mjr 100:1ff35c07217c 332
mjr 100:1ff35c07217c 333 protected:
mjr 100:1ff35c07217c 334 // Generate an SH/ICG pulse. This transfers the pixel data from the live
mjr 100:1ff35c07217c 335 // sensor photoreceptors into the sensor's internal shift register, clears
mjr 100:1ff35c07217c 336 // the live pixels, and starts a new integration cycle.
mjr 100:1ff35c07217c 337 //
mjr 100:1ff35c07217c 338 // If start_dma_xfer is true, we'll start the DMA transfer for the ADC
mjr 100:1ff35c07217c 339 // pixel data. We handle this here because the sensor starts clocking
mjr 100:1ff35c07217c 340 // out pixels precisely at the end of the ICG pulse, so we have to be
mjr 100:1ff35c07217c 341 // be very careful about the timing.
mjr 100:1ff35c07217c 342 //
mjr 100:1ff35c07217c 343 // Returns the timestamp (relative to our image timer 't') of the end
mjr 100:1ff35c07217c 344 // of the SH pulse, which is the moment the new integration cycle starts.
mjr 100:1ff35c07217c 345 //
mjr 100:1ff35c07217c 346 // Note that we send these pulses synchronously - that is, this routine
mjr 100:1ff35c07217c 347 // blocks until the pulses have been sent. The overall sequence takes
mjr 100:1ff35c07217c 348 // about 2.5us to 3us, so it's not a significant interruption of the
mjr 100:1ff35c07217c 349 // main loop.
mjr 100:1ff35c07217c 350 //
mjr 100:1ff35c07217c 351 uint32_t gen_SH_ICG_pulse(bool start_dma_xfer)
mjr 100:1ff35c07217c 352 {
mjr 100:1ff35c07217c 353 // If desired, prepare to start the DMA transfer for the ADC data.
mjr 100:1ff35c07217c 354 // (Set up a dummy location to write in lieu of the DMA register if
mjr 100:1ff35c07217c 355 // DMA initiation isn't required, so that we don't have to take the
mjr 100:1ff35c07217c 356 // time for a conditional when we're ready to start the DMA transfer.
mjr 100:1ff35c07217c 357 // The timing there will be extremely tight, and we can't afford the
mjr 100:1ff35c07217c 358 // extra instructions to test a condition.)
mjr 100:1ff35c07217c 359 uint8_t dma_chcfg_dummy = 0;
mjr 100:1ff35c07217c 360 volatile uint8_t *dma_chcfg = start_dma_xfer ? os_dma.prepare(nPixSensor, true) : &dma_chcfg_dummy;
mjr 100:1ff35c07217c 361
mjr 100:1ff35c07217c 362 // The basic idea is to take ICG low, and while holding ICG low,
mjr 100:1ff35c07217c 363 // pulse SH. The coincidence of the two pulses transfers the charge
mjr 100:1ff35c07217c 364 // from the live pixels into the shift register, which effectively
mjr 100:1ff35c07217c 365 // discharges the live pixels and thereby starts a new integration
mjr 100:1ff35c07217c 366 // cycle.
mjr 100:1ff35c07217c 367 //
mjr 100:1ff35c07217c 368 // The timing of the pulse sequence is rather tightly constrained
mjr 100:1ff35c07217c 369 // per the data sheet, so we have to take some care in executing it:
mjr 100:1ff35c07217c 370 //
mjr 100:1ff35c07217c 371 // ICG -> LOW
mjr 100:1ff35c07217c 372 // 100-1000 ns delay (*)
mjr 100:1ff35c07217c 373 // SH -> HIGH
mjr 100:1ff35c07217c 374 // >1000ns delay
mjr 100:1ff35c07217c 375 // SH -> LOW
mjr 100:1ff35c07217c 376 // >1000ns delay
mjr 100:1ff35c07217c 377 // ICG -> high (**)
mjr 100:1ff35c07217c 378 //
mjr 100:1ff35c07217c 379 // There are two steps here that are tricky:
mjr 100:1ff35c07217c 380 //
mjr 100:1ff35c07217c 381 // (*) is a narrow window that we can't achieve with an mbed
mjr 100:1ff35c07217c 382 // microsecond timer. Instead, we'll do a couple of extra writes
mjr 100:1ff35c07217c 383 // to the ICG register, which take about 60ns each.
mjr 100:1ff35c07217c 384 //
mjr 100:1ff35c07217c 385 // (**) has the rather severe constraint that the transition must
mjr 100:1ff35c07217c 386 // occur AND complete while the master clock is high. Other people
mjr 100:1ff35c07217c 387 // working with similar Toshiba chips in MCU projects have suggested
mjr 100:1ff35c07217c 388 // that this constraint can safely be ignored, so maybe the data
mjr 100:1ff35c07217c 389 // sheet's insistence about it is obsolete advice from past Toshiba
mjr 100:1ff35c07217c 390 // sensors that the doc writers carried forward by copy-and-paste.
mjr 100:1ff35c07217c 391 // Toshiba has been making these sorts of chips for a very long time,
mjr 100:1ff35c07217c 392 // and the data sheets for many of them are obvious copy-and-paste
mjr 100:1ff35c07217c 393 // jobs. But let's take the data sheet at its word and assume that
mjr 100:1ff35c07217c 394 // this is important for proper operation. Our best hope of
mjr 100:1ff35c07217c 395 // satisfying this constraint is to synchronize the start of the
mjr 100:1ff35c07217c 396 // ICG->high transition with the start of a TPM cycle on the master
mjr 100:1ff35c07217c 397 // clock. That guarantees that the ICG transition starts when the
mjr 100:1ff35c07217c 398 // clock signal is high (as each TPM cycle starts out high), and
mjr 100:1ff35c07217c 399 // gives us the longest possible runway for the transition to
mjr 100:1ff35c07217c 400 // complete while the clock is still high, as we get the full
mjr 100:1ff35c07217c 401 // length of the high part of the cycle to work with. To quantify,
mjr 100:1ff35c07217c 402 // it gives us about 600ns. The register write takes about 60ns,
mjr 100:1ff35c07217c 403 // and waitEndCycle() adds several instructions of overhead, perhaps
mjr 100:1ff35c07217c 404 // 200ns, so we get around 300ns for the transition to finish. That
mjr 100:1ff35c07217c 405 // should be a gracious plenty assuming that the hardware is set up
mjr 100:1ff35c07217c 406 // with an inverter to buffer the clock signals. The inverter should
mjr 100:1ff35c07217c 407 // be able to pull up the 35pF on ICG in a "typical" 30ns (rise time
mjr 100:1ff35c07217c 408 // plus propagation delay, per the 74HC04 data sheet) and max 150ns.
mjr 100:1ff35c07217c 409 // This seems to be one place where the inverter might really be
mjr 100:1ff35c07217c 410 // necessary to meet the timing requirements, as the KL25Z GPIO
mjr 100:1ff35c07217c 411 // might need more like 2us to pull that load up.
mjr 100:1ff35c07217c 412 //
mjr 100:1ff35c07217c 413 // There's an additional constraint on the timing at the end of the
mjr 100:1ff35c07217c 414 // ICG pulse. The sensor starts clocking out pixels on the rising
mjr 100:1ff35c07217c 415 // edge of the ICG pulse. So we need the ICG pulse end to align
mjr 100:1ff35c07217c 416 // with the start of an ADC cycle. If we get that wrong, all of our
mjr 100:1ff35c07217c 417 // ADC samples will be off by half a clock, so every sample will be
mjr 100:1ff35c07217c 418 // the average of two adjacent pixels instead of one pixel. That
mjr 100:1ff35c07217c 419 // would lose half of the image resolution, which would obviously
mjr 100:1ff35c07217c 420 // be bad. So make certain we're at the tail end of an ADC cycle
mjr 100:1ff35c07217c 421 // by waiting for the ADC "ready" bit to be set.
mjr 100:1ff35c07217c 422 //
mjr 100:1ff35c07217c 423 // The end of the SH pulse triggers the start of a new integration
mjr 100:1ff35c07217c 424 // cycle, so note the time of that pulse for image timestamping
mjr 100:1ff35c07217c 425 // purposes. That will be the start time of the NEXT image we
mjr 100:1ff35c07217c 426 // transfer after we shift out the current sensor pixels, which
mjr 100:1ff35c07217c 427 // represent the pixels from the last time we pulsed SH.
mjr 100:1ff35c07217c 428 //
mjr 100:1ff35c07217c 429 icg = logicLow;
mjr 100:1ff35c07217c 430 icg = logicLow; // for timing, adds about 60ns
mjr 100:1ff35c07217c 431 icg = logicLow; // ditto, another 60ns, total is now 120ns > min 100ns
mjr 100:1ff35c07217c 432 sh = logicHigh;
mjr 100:1ff35c07217c 433 wait_us(1); // >1000ns delay
mjr 100:1ff35c07217c 434 sh = logicLow;
mjr 100:1ff35c07217c 435 uint32_t t_sh = t.read_us(); // this is the start time of the NEXT image
mjr 100:1ff35c07217c 436 wait_us(1); // >1000ns delay
mjr 100:1ff35c07217c 437
mjr 100:1ff35c07217c 438 // Now the tricky part! We have to end the ICG pulse (take ICG high)
mjr 100:1ff35c07217c 439 // at the start of a master clock cycle, AND at the start of an ADC
mjr 100:1ff35c07217c 440 // sampling cycle. The sensor will start clocking out pixels the
mjr 100:1ff35c07217c 441 // instance ICG goes high, so we have to align our ADC cycle so that
mjr 100:1ff35c07217c 442 // we start a sample at almost exactly the same time we take ICG
mjr 100:1ff35c07217c 443 // high.
mjr 100:1ff35c07217c 444 //
mjr 100:1ff35c07217c 445 // Now, every ADC sampling cycle always starts at a rising edge of
mjr 100:1ff35c07217c 446 // the master clock, since the master clock is the ADC trigger. BUT,
mjr 100:1ff35c07217c 447 // the converse is NOT true: every rising edge of the master clock
mjr 100:1ff35c07217c 448 // is NOT an ADC sample start. Recall that we've contrived the timing
mjr 100:1ff35c07217c 449 // so that every OTHER master clock rising edge starts an ADC sample.
mjr 100:1ff35c07217c 450 //
mjr 100:1ff35c07217c 451 // So how do we detect which part of the clock cycle we're in? We
mjr 100:1ff35c07217c 452 // could conceivably use the COCO bit in the ADC status register to
mjr 100:1ff35c07217c 453 // detect the little window between the end of one sample and the
mjr 100:1ff35c07217c 454 // start of the next. Unfortunately, this doesn't work: the COCO
mjr 100:1ff35c07217c 455 // bit is never actually set for the duration of even a single CPU
mjr 100:1ff35c07217c 456 // instruction in our setup, no matter how loose we make the timing
mjr 100:1ff35c07217c 457 // between the ADC and the fM cycle. I think the reason is the DMA
mjr 100:1ff35c07217c 458 // setup: the COCO bit triggers the DMA, and the DMA controller
mjr 100:1ff35c07217c 459 // reads the ADC result register (the DMA source in our setup),
mjr 100:1ff35c07217c 460 // which has the side effect of clearing COCO. I've experimented
mjr 100:1ff35c07217c 461 // with this using different timing parameters, and the result is
mjr 100:1ff35c07217c 462 // always the same: the CPU *never* sees the COCO bit set. The DMA
mjr 100:1ff35c07217c 463 // trigger timing is evidently deterministic such that the DMA unit
mjr 100:1ff35c07217c 464 // invariably gets its shot at reading ADC0->R before the CPU does.
mjr 100:1ff35c07217c 465 //
mjr 100:1ff35c07217c 466 // The COCO approach would be a little iffy anyway, since we want the
mjr 100:1ff35c07217c 467 // ADC idle time to be as short as possible, which wouldn't give us
mjr 100:1ff35c07217c 468 // much time to do all we have to do in the COCO period, even if
mjr 100:1ff35c07217c 469 // there were one. What we can do instead is seize control of the
mjr 100:1ff35c07217c 470 // ADC cycle timing: rather than trying to detect when the cycle
mjr 100:1ff35c07217c 471 // ends, we can specify when it begins. We can do this by canceling
mjr 100:1ff35c07217c 472 // the TPM->ADC trigger and aborting any conversion in progress, then
mjr 100:1ff35c07217c 473 // reprogramming the TPM->ADC trigger at our leisure. What we *can*
mjr 100:1ff35c07217c 474 // detect reliably is the start of a TPM cycle. So here's our
mjr 100:1ff35c07217c 475 // strategy:
mjr 100:1ff35c07217c 476 //
mjr 100:1ff35c07217c 477 // - Turn off the TPM->ADC trigger and abort the current conversion
mjr 100:1ff35c07217c 478 // - Wait until a new TPM cycle starts
mjr 100:1ff35c07217c 479 // - Reset the TPM->ADC trigger. The first new conversion will
mjr 100:1ff35c07217c 480 // start on the next TPM cycle, so we have the remainder of
mjr 100:1ff35c07217c 481 // the current TPM cycle to make this happen (about 1us, enough
mjr 100:1ff35c07217c 482 // for 16 CPU instructions - plenty for this step)
mjr 100:1ff35c07217c 483 // - Wait for the new TPM cycle
mjr 100:1ff35c07217c 484 // - End the ICG pulse
mjr 100:1ff35c07217c 485 //
mjr 100:1ff35c07217c 486
mjr 100:1ff35c07217c 487 // The timing is so tight here that we want to be sure we're not
mjr 100:1ff35c07217c 488 // interrupted by other tasks - disable interrupts.
mjr 100:1ff35c07217c 489 __disable_irq();
mjr 100:1ff35c07217c 490
mjr 100:1ff35c07217c 491 // disable the TPM->ADC trigger and abort the current conversion
mjr 100:1ff35c07217c 492 os.stop();
mjr 100:1ff35c07217c 493
mjr 100:1ff35c07217c 494 // Enable the DMA controller for the new transfer from the ADC.
mjr 100:1ff35c07217c 495 // The sensor will start clocking out new samples at the ICG rising
mjr 100:1ff35c07217c 496 // edge, so the next ADC sample to complete will represent the first
mjr 100:1ff35c07217c 497 // pixel in the new frame. So we need the DMA ready to go at the
mjr 100:1ff35c07217c 498 // very next sample. Recall that the DMA is triggered by ADC
mjr 100:1ff35c07217c 499 // completion, and ADC is stopped right now, so enabling the DMA
mjr 100:1ff35c07217c 500 // won't have any immediate effect - it just spools it up so that
mjr 100:1ff35c07217c 501 // it's ready to move samples as soon as we resume the ADC.
mjr 100:1ff35c07217c 502 *dma_chcfg |= DMAMUX_CHCFG_ENBL_MASK;
mjr 100:1ff35c07217c 503
mjr 100:1ff35c07217c 504 // wait for the start of a new master clock cycle
mjr 100:1ff35c07217c 505 fm.waitEndCycle();
mjr 100:1ff35c07217c 506
mjr 100:1ff35c07217c 507 // Okay, a master clock cycle just started, so we have about 1us
mjr 100:1ff35c07217c 508 // (about 16 CPU instructions) before the next one begins. Resume
mjr 100:1ff35c07217c 509 // ADC sampling. The first new sample will start with the next
mjr 100:1ff35c07217c 510 // TPM cycle 1us from now. (This step takes about 3 instructions.)
mjr 100:1ff35c07217c 511 os.resume();
mjr 100:1ff35c07217c 512
mjr 100:1ff35c07217c 513 // Okay, everything is queued up! We just have to fire the starting
mjr 100:1ff35c07217c 514 // pistol on the sensor at the right moment. And that right moment
mjr 100:1ff35c07217c 515 // is the start of the next TPM cycle. Wait for it...
mjr 100:1ff35c07217c 516 fm.waitEndCycle();
mjr 100:1ff35c07217c 517
mjr 100:1ff35c07217c 518 // And go!
mjr 100:1ff35c07217c 519 icg = logicHigh;
mjr 100:1ff35c07217c 520
mjr 100:1ff35c07217c 521 // note the start time of the transfer
mjr 100:1ff35c07217c 522 tXfer = t.read_us();
mjr 100:1ff35c07217c 523
mjr 100:1ff35c07217c 524 // done with the critical timing section
mjr 100:1ff35c07217c 525 __enable_irq();
mjr 100:1ff35c07217c 526
mjr 100:1ff35c07217c 527 // return the timestamp of the end of the SH pulse - this is the start
mjr 100:1ff35c07217c 528 // of the new integration period that we just initiated
mjr 100:1ff35c07217c 529 return t_sh;
mjr 100:1ff35c07217c 530 }
mjr 100:1ff35c07217c 531
mjr 100:1ff35c07217c 532 // end of transfer notification
mjr 100:1ff35c07217c 533 void transferDone()
mjr 100:1ff35c07217c 534 {
mjr 100:1ff35c07217c 535 // add this sample to the timing statistics (for diagnostics and
mjr 100:1ff35c07217c 536 // performance measurement)
mjr 100:1ff35c07217c 537 uint32_t dt = dtPixXfer = static_cast<uint32_t>(t.read_us() - tXfer);
mjr 100:1ff35c07217c 538 totalXferTime += dt;
mjr 100:1ff35c07217c 539 nRuns += 1;
mjr 100:1ff35c07217c 540
mjr 100:1ff35c07217c 541 // collect debug statistics
mjr 100:1ff35c07217c 542 if (dt < minXferTime) minXferTime = dt;
mjr 100:1ff35c07217c 543 if (dt > maxXferTime) maxXferTime = dt;
mjr 100:1ff35c07217c 544
mjr 100:1ff35c07217c 545 // the sampler is no long running
mjr 100:1ff35c07217c 546 running = false;
mjr 100:1ff35c07217c 547 }
mjr 100:1ff35c07217c 548
mjr 100:1ff35c07217c 549 // master clock
mjr 100:1ff35c07217c 550 NewPwmOut fm;
mjr 100:1ff35c07217c 551
mjr 100:1ff35c07217c 552 // analog input for reading the pixel voltage level
mjr 100:1ff35c07217c 553 AltAnalogIn_8bit os;
mjr 100:1ff35c07217c 554
mjr 100:1ff35c07217c 555 // Integration Clear Gate output
mjr 100:1ff35c07217c 556 DigitalOut icg;
mjr 100:1ff35c07217c 557
mjr 100:1ff35c07217c 558 // Shift Gate output
mjr 100:1ff35c07217c 559 DigitalOut sh;
mjr 100:1ff35c07217c 560
mjr 100:1ff35c07217c 561 // DMA channel for the analog input
mjr 100:1ff35c07217c 562 SimpleDMA os_dma;
mjr 100:1ff35c07217c 563
mjr 100:1ff35c07217c 564 // Master clock period, in seconds, calculated based on the ADC timing
mjr 100:1ff35c07217c 565 float masterClockPeriod;
mjr 100:1ff35c07217c 566
mjr 100:1ff35c07217c 567 // Number of pixels. The TCD1103 has 1500 image pixels, plus 32 dummy
mjr 100:1ff35c07217c 568 // pixels at the front end (before the first image pixel) and another 14
mjr 100:1ff35c07217c 569 // dummy pixels at the back end. The sensor always transfers the full
mjr 100:1ff35c07217c 570 // file on each read cycle, including the dummies, so we have to make
mjr 100:1ff35c07217c 571 // room for the dummy pixels during each read.
mjr 100:1ff35c07217c 572 static const int nPixSensor = 1546;
mjr 100:1ff35c07217c 573
mjr 100:1ff35c07217c 574 // pixel buffers - we keep two buffers so that we can transfer the
mjr 100:1ff35c07217c 575 // current sensor data into one buffer via DMA while we concurrently
mjr 100:1ff35c07217c 576 // process the last buffer
mjr 100:1ff35c07217c 577 uint8_t *pix1; // pixel array 1
mjr 100:1ff35c07217c 578 uint8_t *pix2; // pixel array 2
mjr 100:1ff35c07217c 579
mjr 100:1ff35c07217c 580 // Timestamps of pix1 and pix2 arrays, in microseconds, in terms of the
mjr 100:1ff35c07217c 581 // sample timer (this->t).
mjr 100:1ff35c07217c 582 uint32_t t1;
mjr 100:1ff35c07217c 583 uint32_t t2;
mjr 100:1ff35c07217c 584
mjr 100:1ff35c07217c 585 // DMA target buffer. This is the buffer for the next DMA transfer.
mjr 100:1ff35c07217c 586 // 0 means pix1, 1 means pix2. The other buffer contains the stable
mjr 100:1ff35c07217c 587 // data from the last transfer.
mjr 100:1ff35c07217c 588 uint8_t pixDMA;
mjr 100:1ff35c07217c 589
mjr 100:1ff35c07217c 590 // flag: sample is running
mjr 100:1ff35c07217c 591 volatile bool running;
mjr 100:1ff35c07217c 592
mjr 100:1ff35c07217c 593 // timing statistics
mjr 100:1ff35c07217c 594 Timer t; // sample timer
mjr 100:1ff35c07217c 595 uint32_t tInt; // start time (us) of current integration period
mjr 100:1ff35c07217c 596 uint32_t tXfer; // start time (us) of current pixel transfer
mjr 100:1ff35c07217c 597 uint32_t dtPixXfer; // pixel transfer time of last frame
mjr 100:1ff35c07217c 598 uint64_t totalXferTime; // total time consumed by all reads so far
mjr 100:1ff35c07217c 599 uint32_t nRuns; // number of runs so far
mjr 100:1ff35c07217c 600
mjr 100:1ff35c07217c 601 // debugging - min/max transfer time statistics
mjr 100:1ff35c07217c 602 uint32_t minXferTime;
mjr 100:1ff35c07217c 603 uint32_t maxXferTime;
mjr 100:1ff35c07217c 604 };