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

Dependencies:   mbed FastIO FastPWM USBDevice

Fork of Pinscape_Controller by Mike R


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

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

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

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


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


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

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

System Requirements

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

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

Main Features

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

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

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

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

Expansion Boards

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

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

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

Expansion Board project page

Update notes

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

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

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

New Features

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

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

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

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

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

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

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

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

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

More Downloads

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

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

Copyright and License

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

Warning to VirtuaPin Kit Owners

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

Fri Nov 29 05:38:07 2019 +0000
Use continuous asynchronous frame transfers in image sensors

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 82:4f6209cb5c33 1 /*
mjr 82:4f6209cb5c33 2 * AMS/TAOS TSL14xx series photodiode array interface class.
mjr 82:4f6209cb5c33 3 *
mjr 82:4f6209cb5c33 4 * This provides a high-level interface for the AMS/TAOS TSLxx series
mjr 82:4f6209cb5c33 5 * of photodiode arrays. This class works with most of the sensors
mjr 82:4f6209cb5c33 6 * in this series, which differ only in pixel array sizes. This code
mjr 82:4f6209cb5c33 7 * has been tested with the following sensors from the series:
mjr 82:4f6209cb5c33 8 *
mjr 82:4f6209cb5c33 9 * TSL1410R - 1280 pixels, 400dpi
mjr 82:4f6209cb5c33 10 * TSL1412S - 1536 pixels, 400dpi
mjr 82:4f6209cb5c33 11 * TSL1401CL - 128 pixels, 400dpi
mjr 82:4f6209cb5c33 12 *
mjr 82:4f6209cb5c33 13 * All of these sensors have the same electrical interface, consisting
mjr 82:4f6209cb5c33 14 * of a clock input (CLK), start pulse input (SI), and analog pixel
mjr 82:4f6209cb5c33 15 * output (AO). The sensors are equipped with hold capacitors and
mjr 82:4f6209cb5c33 16 * shift registers that allow simultaneous sampling of all pixels, and
mjr 82:4f6209cb5c33 17 * serial access to the pixel values.
mjr 82:4f6209cb5c33 18 *
mjr 82:4f6209cb5c33 19 * (Note on the plunger sensor class hierarchy: this class is for the
mjr 82:4f6209cb5c33 20 * sensor only, not for the plunger application. This class is meant
mjr 82:4f6209cb5c33 21 * to be reusable in other contexts that just need to read raw pixel
mjr 82:4f6209cb5c33 22 * data from the sensor. Plunger/tslxxSensor.h implements the next
mjr 82:4f6209cb5c33 23 * level up, which is the implementation of the generic plunger sensor
mjr 82:4f6209cb5c33 24 * interface for TSL14xx sensors. That's still an abstract class, since
mjr 82:4f6209cb5c33 25 * it only provides the plunger class specialization for these sensor
mjr 82:4f6209cb5c33 26 * types, without any image analysis component. The final concrete
mjr 82:4f6209cb5c33 27 * classes are in Plunger/edgeSensor.h and Plunger/barCodeSensor.h,
mjr 82:4f6209cb5c33 28 * which add the image processing that analyzes the image data to
mjr 82:4f6209cb5c33 29 * determine the plunger position.)
mjr 82:4f6209cb5c33 30 *
mjr 101:755f44622abc 31 * *** Double buffering ***
mjr 101:755f44622abc 32 *
mjr 82:4f6209cb5c33 33 * Our API is based on a double-buffered asynchronous read. The caller
mjr 82:4f6209cb5c33 34 * can access a completed buffer, containing the pixels from the last image
mjr 82:4f6209cb5c33 35 * frame, while the sensor is transferring data asynchronously (using the
mjr 82:4f6209cb5c33 36 * microcontroller's DMA capability) into the other buffer. Each time a
mjr 82:4f6209cb5c33 37 * new read is started, we swap buffers, making the last completed buffer
mjr 82:4f6209cb5c33 38 * available to the client and handing the other buffer to the DMA
mjr 82:4f6209cb5c33 39 * controller to fill asynchronously.
mjr 101:755f44622abc 40 *
mjr 101:755f44622abc 41 * In a way, there are actually THREE frames in our pipeline at any given
mjr 101:755f44622abc 42 * time:
mjr 101:755f44622abc 43 *
mjr 101:755f44622abc 44 * - a live image integrating light on the photo receptors on the sensor
mjr 101:755f44622abc 45 * - the prior image, held in the sensor's shift register and being
mjr 101:755f44622abc 46 * transferred via DMA into one of our buffers (the "DMA" buffer)
mjr 101:755f44622abc 47 * - the second prior image, in our other buffer (the "stable" buffer),
mjr 101:755f44622abc 48 * available for the client to process
mjr 101:755f44622abc 49 *
mjr 101:755f44622abc 50 * The integration process on the sensor starts when we begin the transfer
mjr 101:755f44622abc 51 * of an image via DMA. That frame's integration period ends when the next
mjr 101:755f44622abc 52 * transfer starts. So the minimum integration time is also the DMA pixel
mjr 101:755f44622abc 53 * transfer time. Longer integration times can be achieved by waiting
mjr 101:755f44622abc 54 * for an additional interval after a DMA transfer finishes, before starting
mjr 101:755f44622abc 55 * the next transfer. We make provision for this added time to allow for
mjr 101:755f44622abc 56 * longer exposure times to optimize image quality.
mjr 101:755f44622abc 57 *
mjr 82:4f6209cb5c33 58 *
mjr 101:755f44622abc 59 * *** Optimizing pixel transfer speed ***
mjr 82:4f6209cb5c33 60 *
mjr 101:755f44622abc 61 * For Pinscape purposes, we want the fastest possible frame rate, as we're
mjr 101:755f44622abc 62 * trying to accurately capture the motion of a fast-moving object (the
mjr 101:755f44622abc 63 * plunger). The TSL14xx sensors can achieve a frame rate up to about
mjr 101:755f44622abc 64 * 1000 frames per second, if everything is clocked at the limits in the
mjr 101:755f44622abc 65 * data sheet. The KL25Z, however, can't achieve that fast a rate. The
mjr 101:755f44622abc 66 * limiting factor is the KL25Z's ADC. We have to take an ADC sample for
mjr 101:755f44622abc 67 * every pixel, and the minimum sampling time for the ADC on the KL25Z is
mjr 101:755f44622abc 68 * about 2us. With the 1280-pixel TSL1410R, that gives us a minimum
mjr 101:755f44622abc 69 * pixel transfer time of about 2.6ms. And it's actually very difficult
mjr 101:755f44622abc 70 * to achieve that speed - my original, naive implementation took more
mjr 101:755f44622abc 71 * like 30ms (!!!) to transfer each frame.
mjr 82:4f6209cb5c33 72 *
mjr 101:755f44622abc 73 * As a rule, I don't like tricky code, because it's hard to understand
mjr 101:755f44622abc 74 * and hard to debug. But in this case it's justified. For good plunger
mjr 101:755f44622abc 75 * tracking, it's critical to achieve a minimum frame rate of around 200
mjr 101:755f44622abc 76 * fps (5ms per frame). I'm pretty sure there's no way to even get close
mjr 101:755f44622abc 77 * to this rate without the complex setup described below.
mjr 101:755f44622abc 78 *
mjr 101:755f44622abc 79 * Here's our approach for fast data transfer:
mjr 82:4f6209cb5c33 80 *
mjr 82:4f6209cb5c33 81 * First, we put the analog input port (the ADC == Analog-to-Digital
mjr 82:4f6209cb5c33 82 * Converter) in "continuous" mode, at the highest clock speed we can
mjr 82:4f6209cb5c33 83 * program with the available clocks and the fastest read cycle
mjr 82:4f6209cb5c33 84 * available in the ADC hardware. (The analog input port is the
mjr 82:4f6209cb5c33 85 * GPIO pin attached to the sensor's AO == Analog Output pin, where
mjr 82:4f6209cb5c33 86 * it outputs each pixel's value, one at a time, as an analog voltage
mjr 82:4f6209cb5c33 87 * level.) In continuous mode, every time the ADC finishes taking a
mjr 82:4f6209cb5c33 88 * sample, it stores the result value in its output register and then
mjr 82:4f6209cb5c33 89 * immediately starts taking a new sample. This means that no MCU
mjr 82:4f6209cb5c33 90 * (or even DMA) action is required to start each new sample. This
mjr 82:4f6209cb5c33 91 * is where most of the speedup comes from, since it takes significant
mjr 82:4f6209cb5c33 92 * time (multiple microseconds) to move data through the peripheral
mjr 82:4f6209cb5c33 93 * registers, and it takes more time (also multiple microseconds) for
mjr 82:4f6209cb5c33 94 * the ADC to spin up for each new sample when in single-sample mode.
mjr 82:4f6209cb5c33 95 * We cut out about 7us this way and get the time per sample down to
mjr 82:4f6209cb5c33 96 * about 2us. This is close to the documented maximum speed for the
mjr 82:4f6209cb5c33 97 * ADC hardware.
mjr 82:4f6209cb5c33 98 *
mjr 82:4f6209cb5c33 99 * Second, we use the DMA controller to read the ADC result register
mjr 82:4f6209cb5c33 100 * and store each sample in a memory array for processing. The ADC
mjr 82:4f6209cb5c33 101 * hardware is designed to work with the DMA controller by signaling
mjr 82:4f6209cb5c33 102 * the DMA controller when a new sample is ready; this allows DMA to
mjr 82:4f6209cb5c33 103 * move each sample immediately when it's available without any CPU
mjr 82:4f6209cb5c33 104 * involvement.
mjr 82:4f6209cb5c33 105 *
mjr 82:4f6209cb5c33 106 * Third - and this is where it really gets tricky - we use two
mjr 82:4f6209cb5c33 107 * additional "linked" DMA channels to generate the clock signal
mjr 82:4f6209cb5c33 108 * to the CCD sensor. The clock signal is how we tell the CCD when
mjr 82:4f6209cb5c33 109 * to place the next pixel voltage on its AO pin, so the clock has
mjr 82:4f6209cb5c33 110 * to be generated in lock step with the ADC sampling cycle. The
mjr 82:4f6209cb5c33 111 * ADC timing isn't perfectly uniform or predictable, so we can't
mjr 82:4f6209cb5c33 112 * just generate the pixel clock with a *real* clock. We have to
mjr 82:4f6209cb5c33 113 * time the signal exactly with the ADC, which means that we have
mjr 82:4f6209cb5c33 114 * to generate it from the ADC "sample is ready" signal. Fortunately,
mjr 82:4f6209cb5c33 115 * there is just such a signal, and in fact we're already using it,
mjr 82:4f6209cb5c33 116 * as described above, to tell the DMA when to move each result from
mjr 82:4f6209cb5c33 117 * the ADC output register to our memory array. So how do we use this
mjr 82:4f6209cb5c33 118 * to generate the CCD clock? The answer lies in the DMA controller's
mjr 82:4f6209cb5c33 119 * channel linking feature. This allows one DMA channel to trigger a
mjr 82:4f6209cb5c33 120 * second DMA channel each time the first channel completes one
mjr 82:4f6209cb5c33 121 * transfer. And we can use DMA to control our clock GPIO pin by
mjr 82:4f6209cb5c33 122 * using the pin's GPIO IPORT register as the DMA destination address.
mjr 82:4f6209cb5c33 123 * Specifically, we can take the clock high by writing our pin's bit
mjr 82:4f6209cb5c33 124 * pattern to the PSOR ("set output") register, and we can take the
mjr 82:4f6209cb5c33 125 * clock low by writing to the PCOR ("clear output") register. We
mjr 82:4f6209cb5c33 126 * use one DMA channel for each of these operations.
mjr 82:4f6209cb5c33 127 *
mjr 82:4f6209cb5c33 128 * Putting it all together, the cascade of linked DMA channels
mjr 82:4f6209cb5c33 129 * works like this:
mjr 82:4f6209cb5c33 130 *
mjr 82:4f6209cb5c33 131 * - We kick off the first ADC sample.
mjr 82:4f6209cb5c33 132 *
mjr 82:4f6209cb5c33 133 * - When the ADC sample completes, the ADC DMA trigger fires,
mjr 82:4f6209cb5c33 134 * which triggers channel 1, the "Clock Up" channel. This
mjr 82:4f6209cb5c33 135 * performs one transfer of the clock GPIO bit to the clock
mjr 82:4f6209cb5c33 136 * PSOR register, taking the clock high, which causes the CCD
mjr 82:4f6209cb5c33 137 * to move the next pixel onto AO.
mjr 82:4f6209cb5c33 138 *
mjr 82:4f6209cb5c33 139 * - After the Clock Up channel does its transfer, it triggers
mjr 82:4f6209cb5c33 140 * its link to channel 2, the ADC transfer channel. This
mjr 82:4f6209cb5c33 141 * channel moves the ADC output register value to our memory
mjr 82:4f6209cb5c33 142 * array.
mjr 82:4f6209cb5c33 143 *
mjr 82:4f6209cb5c33 144 * - After the ADC channel does its transfer, it triggers channel
mjr 82:4f6209cb5c33 145 * 3, the "Clock Down" channel. This performs one transfer of
mjr 82:4f6209cb5c33 146 * the clock GPIO bit to the clock PCOR register, taking the
mjr 82:4f6209cb5c33 147 * clock low.
mjr 82:4f6209cb5c33 148 *
mjr 82:4f6209cb5c33 149 * Note that the order of the channels - Clock Up, ADC, Clock Down -
mjr 82:4f6209cb5c33 150 * is important. It ensures that we don't toggle the clock line
mjr 82:4f6209cb5c33 151 * too quickly. The CCD has a minimum pulse duration of 50ns for
mjr 82:4f6209cb5c33 152 * the clock signal. The DMA controller is so fast that it might
mjr 82:4f6209cb5c33 153 * toggle the clock faster than this limit if we did the Up and
mjr 82:4f6209cb5c33 154 * Down transfers back-to-back.
mjr 82:4f6209cb5c33 155 *
mjr 82:4f6209cb5c33 156 * Note also that it's important for Clock Up to be the very first
mjr 82:4f6209cb5c33 157 * operation after the DMA trigger. The ADC is in continuous mode,
mjr 82:4f6209cb5c33 158 * meaning that it starts taking a new sample immediately upon
mjr 82:4f6209cb5c33 159 * finishing the previous one. So when the ADC DMA signal fires,
mjr 82:4f6209cb5c33 160 * the new sample is already starting. We therefore have to get
mjr 82:4f6209cb5c33 161 * the next pixel onto the sampling pin immediately, or as close
mjr 82:4f6209cb5c33 162 * to immediately as possible. The sensor's "analog output
mjr 82:4f6209cb5c33 163 * settling time" is 120ns - this is the time for a new pixel
mjr 82:4f6209cb5c33 164 * voltage to stabilize on AO after a clock rising edge. So
mjr 82:4f6209cb5c33 165 * assuming that the ADC raises the DMA signal immediately on
mjr 82:4f6209cb5c33 166 * sample completion, and the DMA controller responds within a
mjr 82:4f6209cb5c33 167 * couple of MCU clock cycles, we should have the new pixel voltage
mjr 82:4f6209cb5c33 168 * stable on the sampling pin by about 200ns after the new ADC
mjr 82:4f6209cb5c33 169 * sample cycle starts. The sampling cycle with our current
mjr 82:4f6209cb5c33 170 * parameters is about 2us, so the voltage level is stable for
mjr 82:4f6209cb5c33 171 * 90% of the cycle.
mjr 82:4f6209cb5c33 172 *
mjr 82:4f6209cb5c33 173 * Also, note that it's okay that the ADC sample transfer doesn't
mjr 82:4f6209cb5c33 174 * happen until after the Clock Up DMA transfer. The ADC output
mjr 82:4f6209cb5c33 175 * register holds the last result until the next sample completes,
mjr 82:4f6209cb5c33 176 * so we have about 2us to grab it. The first Clock Up DMA
mjr 82:4f6209cb5c33 177 * transfer only takes a couple of clocks - order of 100ns - so
mjr 82:4f6209cb5c33 178 * we get to it with time to spare.
mjr 82:4f6209cb5c33 179 *
mjr 82:4f6209cb5c33 180 * (Note that it would nicer to handle the clock with a single DMA
mjr 82:4f6209cb5c33 181 * channel, since DMA channels are a limited resource. We could
mjr 82:4f6209cb5c33 182 * conceivably consolidate the clock generator one DMA channel by
mjr 82:4f6209cb5c33 183 * switching the DMA destination to the PTOR "toggle" register, and
mjr 82:4f6209cb5c33 184 * writing *two* times per trigger - once to toggle the clock up,
mjr 82:4f6209cb5c33 185 * and a second time to toggle it down. But I haven't found a way
mjr 82:4f6209cb5c33 186 * to make this work. The obstacle is that the DMA controller can
mjr 82:4f6209cb5c33 187 * only do one transfer per trigger in the fully autonomous mode
mjr 82:4f6209cb5c33 188 * we're using, and to make this toggle scheme work, we'd have to do
mjr 82:4f6209cb5c33 189 * two writes per trigger. Maybe even three or four: I think we'd
mjr 82:4f6209cb5c33 190 * have to throw in one or two no-op writes (of all zeroes) between
mjr 82:4f6209cb5c33 191 * the two toggles, to pad the timing to ensure that the clock pulse
mjr 82:4f6209cb5c33 192 * width is over the sensor's 50ns minimum. But it's the same issue
mjr 82:4f6209cb5c33 193 * whether it's two writes or four. The DMA controller does have a
mjr 82:4f6209cb5c33 194 * "continuous" mode that does an entire transfer on a single trigger,
mjr 82:4f6209cb5c33 195 * but it can't reset itself after such a transfer; CPU intervention
mjr 82:4f6209cb5c33 196 * is required to do that, which means we'd have to service an
mjr 82:4f6209cb5c33 197 * interrupt on every ADC cycle to set up the next clock write.
mjr 82:4f6209cb5c33 198 * Given the 2us cycle time, an interrupt would create a ton of CPU
mjr 82:4f6209cb5c33 199 * load, and I don't think the CPU is fast enough to reliably complete
mjr 82:4f6209cb5c33 200 * the work we'd have to do on each 2us cycle. Fortunately, at
mjr 82:4f6209cb5c33 201 * the moment we can afford to dedicate three channels to this
mjr 82:4f6209cb5c33 202 * module. We only have one other module using the DMA at all
mjr 82:4f6209cb5c33 203 * (the TLC5940 PWM controller interface), and it only needs one
mjr 82:4f6209cb5c33 204 * channel. So the KL25Z's complement of four DMA channels is just
mjr 82:4f6209cb5c33 205 * enough for all of our needs for the moment.)
mjr 101:755f44622abc 206 *
mjr 101:755f44622abc 207 * Note that some of the sensors in this series (TSL1410R, TSL1412S)
mjr 101:755f44622abc 208 * have a "parallel" readout mode that lets them physically deliver
mjr 101:755f44622abc 209 * two pixels at once the MCU, via separate physical connections. This
mjr 101:755f44622abc 210 * could provide a 2X speedup on an MCU equipped with two independent
mjr 101:755f44622abc 211 * ADC samplers. Unfortunately, the KL25Z is not so equipped; even
mjr 101:755f44622abc 212 * though it might appear at first glance to support multiple ADC
mjr 101:755f44622abc 213 * "channels", all of the channels internally multiplex into a single
mjr 101:755f44622abc 214 * converter unit, so the hardware can ultimately perform only one
mjr 101:755f44622abc 215 * conversion at a time. Paradoxically, using the sensor's parallel
mjr 101:755f44622abc 216 * mode is actually *slower* with a KL25Z than using its serial mode,
mjr 101:755f44622abc 217 * because we can only maintain the higher throughput of the KL25Z ADC's
mjr 101:755f44622abc 218 * continuous sampling mode by reading all samples thorugh a single
mjr 101:755f44622abc 219 * channel. Switching channels on alternating samples involves a
mjr 101:755f44622abc 220 * bunch of setup overhead within the ADC hardware that adds lots of
mjr 101:755f44622abc 221 * clocks compared to single-channel continuous mode.
mjr 82:4f6209cb5c33 222 */
mjr 82:4f6209cb5c33 223
mjr 82:4f6209cb5c33 224 #include "mbed.h"
mjr 82:4f6209cb5c33 225 #include "config.h"
mjr 82:4f6209cb5c33 226 #include "AltAnalogIn.h"
mjr 82:4f6209cb5c33 227 #include "SimpleDMA.h"
mjr 82:4f6209cb5c33 228 #include "DMAChannels.h"
mjr 82:4f6209cb5c33 229
mjr 82:4f6209cb5c33 230 #ifndef TSL14XX_H
mjr 82:4f6209cb5c33 231 #define TSL14XX_H
mjr 82:4f6209cb5c33 232
mjr 82:4f6209cb5c33 233
mjr 82:4f6209cb5c33 234 // To allow DMA access to the clock pin, we need to point the DMA
mjr 82:4f6209cb5c33 235 // controller to the IOPORT registers that control the pin. PORT_BASE()
mjr 82:4f6209cb5c33 236 // gives us the address of the register group for the 32 GPIO pins with
mjr 82:4f6209cb5c33 237 // the same letter name as our target pin (e.g., PTA0 through PTA31),
mjr 82:4f6209cb5c33 238 // and PINMASK gives us the bit pattern to write to those registers to
mjr 82:4f6209cb5c33 239 // access our single GPIO pin. Each register group has three special
mjr 82:4f6209cb5c33 240 // registers that update the pin in particular ways: PSOR ("set output
mjr 82:4f6209cb5c33 241 // register") turns pins on, PCOR ("clear output register") turns pins
mjr 82:4f6209cb5c33 242 // off, and PTOR ("toggle output register") toggle pins to the opposite
mjr 82:4f6209cb5c33 243 // of their current values. These registers have special semantics:
mjr 82:4f6209cb5c33 244 // writing a bit as 0 has no effect on the corresponding pin, while
mjr 82:4f6209cb5c33 245 // writing a bit as 1 performs the register's action on the pin. This
mjr 82:4f6209cb5c33 246 // allows a single GPIO pin to be set, cleared, or toggled with a
mjr 82:4f6209cb5c33 247 // 32-bit write to one of these registers, without affecting any of the
mjr 82:4f6209cb5c33 248 // other pins addressed by the register. (It also allows changing any
mjr 82:4f6209cb5c33 249 // group of pins with a single write, although we don't use that
mjr 82:4f6209cb5c33 250 // feature here.)
mjr 82:4f6209cb5c33 251 //
mjr 82:4f6209cb5c33 252 // - To turn a pin ON: PORT_BASE(pin)->PSOR = PINMASK(pin)
mjr 82:4f6209cb5c33 253 // - To turn a pin OFF: PORT_BASE(pin)->PCOR = PINMASK(pin)
mjr 82:4f6209cb5c33 254 // - To toggle a pin: PORT_BASE(pin)->PTOR = PINMASK(pin)
mjr 82:4f6209cb5c33 255 //
mjr 82:4f6209cb5c33 256 #define GPIO_PORT(pin) (((unsigned int)(pin)) >> PORT_SHIFT)
mjr 82:4f6209cb5c33 257 #define GPIO_PORT_BASE(pin) ((GPIO_Type *)(PTA_BASE + GPIO_PORT(pin) * 0x40))
mjr 82:4f6209cb5c33 258 #define GPIO_PINMASK(pin) gpio_set(pin)
mjr 82:4f6209cb5c33 259
mjr 82:4f6209cb5c33 260 IF_DIAG(
mjr 82:4f6209cb5c33 261 extern uint64_t mainLoopIterCheckpt[];
mjr 82:4f6209cb5c33 262 extern Timer mainLoopTimer;)
mjr 82:4f6209cb5c33 263
mjr 82:4f6209cb5c33 264 class TSL14xx
mjr 82:4f6209cb5c33 265 {
mjr 82:4f6209cb5c33 266 public:
mjr 82:4f6209cb5c33 267 // Set up the interface.
mjr 82:4f6209cb5c33 268 //
mjr 82:4f6209cb5c33 269 // nPixSensor = native number of pixels on sensor
mjr 82:4f6209cb5c33 270 // siPin = SI pin (GPIO, digital out)
mjr 82:4f6209cb5c33 271 // clockPin = CLK pin (GPIO, digital out)
mjr 82:4f6209cb5c33 272 // aoPin = AO pin (GPIO, analog in - must be ADC-capable)
mjr 82:4f6209cb5c33 273 TSL14xx(int nPixSensor, PinName siPin, PinName clockPin, PinName aoPin)
mjr 100:1ff35c07217c 274 : adc_dma(DMAch_TSL_ADC),
mjr 100:1ff35c07217c 275 clkUp_dma(DMAch_TSL_CLKUP),
mjr 100:1ff35c07217c 276 clkDn_dma(DMAch_TSL_CLKDN),
mjr 82:4f6209cb5c33 277 si(siPin),
mjr 82:4f6209cb5c33 278 clock(clockPin),
mjr 100:1ff35c07217c 279 ao(aoPin, true, 0), // continuous sampling, fast sampling mode
mjr 82:4f6209cb5c33 280 nPixSensor(nPixSensor)
mjr 82:4f6209cb5c33 281 {
mjr 100:1ff35c07217c 282 // Calibrate the ADC for best accuracy
mjr 100:1ff35c07217c 283 ao.calibrate();
mjr 100:1ff35c07217c 284
mjr 82:4f6209cb5c33 285 // start the sample timer with an arbitrary zero point of 'now'
mjr 82:4f6209cb5c33 286 t.start();
mjr 82:4f6209cb5c33 287
mjr 101:755f44622abc 288 // start with no minimum integration time
mjr 101:755f44622abc 289 tIntMin = 0;
mjr 101:755f44622abc 290
mjr 82:4f6209cb5c33 291 // allocate our double pixel buffers
mjr 82:4f6209cb5c33 292 pix1 = new uint8_t[nPixSensor*2];
mjr 82:4f6209cb5c33 293 pix2 = pix1 + nPixSensor;
mjr 82:4f6209cb5c33 294
mjr 82:4f6209cb5c33 295 // put the first DMA transfer into the first buffer (pix1)
mjr 82:4f6209cb5c33 296 pixDMA = 0;
mjr 101:755f44622abc 297
mjr 101:755f44622abc 298 // DMA owns both buffers until the first transfer completes
mjr 101:755f44622abc 299 clientOwnsStablePix = true;
mjr 82:4f6209cb5c33 300
mjr 82:4f6209cb5c33 301 // remember the clock pin port base and pin mask for fast access
mjr 82:4f6209cb5c33 302 clockPort = GPIO_PORT_BASE(clockPin);
mjr 82:4f6209cb5c33 303 clockMask = GPIO_PINMASK(clockPin);
mjr 82:4f6209cb5c33 304
mjr 82:4f6209cb5c33 305 // clear out power-on random data by clocking through all pixels twice
mjr 82:4f6209cb5c33 306 clear();
mjr 82:4f6209cb5c33 307 clear();
mjr 82:4f6209cb5c33 308
mjr 82:4f6209cb5c33 309 // Set up the Clock Up DMA channel. This channel takes the
mjr 82:4f6209cb5c33 310 // clock high by writing the clock bit to the PSOR (set output)
mjr 82:4f6209cb5c33 311 // register for the clock pin.
mjr 82:4f6209cb5c33 312 clkUp_dma.source(&clockMask, false, 32);
mjr 82:4f6209cb5c33 313 clkUp_dma.destination(&clockPort->PSOR, false, 32);
mjr 82:4f6209cb5c33 314
mjr 82:4f6209cb5c33 315 // Set up the Clock Down DMA channel. This channel takes the
mjr 82:4f6209cb5c33 316 // clock low by writing the clock bit to the PCOR (clear output)
mjr 82:4f6209cb5c33 317 // register for the clock pin.
mjr 82:4f6209cb5c33 318 clkDn_dma.source(&clockMask, false, 32);
mjr 82:4f6209cb5c33 319 clkDn_dma.destination(&clockPort->PCOR, false, 32);
mjr 82:4f6209cb5c33 320
mjr 82:4f6209cb5c33 321 // Set up the ADC transfer DMA channel. This channel transfers
mjr 82:4f6209cb5c33 322 // the current analog sampling result from the ADC output register
mjr 82:4f6209cb5c33 323 // to our pixel array.
mjr 82:4f6209cb5c33 324 ao.initDMA(&adc_dma);
mjr 82:4f6209cb5c33 325
mjr 82:4f6209cb5c33 326 // Set up our chain of linked DMA channel:
mjr 82:4f6209cb5c33 327 //
mjr 82:4f6209cb5c33 328 // ADC sample completion triggers Clock Up
mjr 82:4f6209cb5c33 329 // ...which triggers the ADC transfer
mjr 82:4f6209cb5c33 330 // ...which triggers Clock Down
mjr 82:4f6209cb5c33 331 //
mjr 82:4f6209cb5c33 332 // We operate the ADC in "continuous mode", meaning that it starts
mjr 82:4f6209cb5c33 333 // a new sample immediately after the last one completes. This is
mjr 82:4f6209cb5c33 334 // what keeps the cycle going after the Clock Down, since the Clock
mjr 82:4f6209cb5c33 335 // Down transfer itself doesn't trigger another DMA operation.
mjr 82:4f6209cb5c33 336 clkUp_dma.trigger(Trigger_ADC0);
mjr 82:4f6209cb5c33 337;
mjr 82:4f6209cb5c33 338, false);
mjr 82:4f6209cb5c33 339
mjr 82:4f6209cb5c33 340 // Set the trigger on the downstream links to NONE - these are
mjr 82:4f6209cb5c33 341 // triggered by their upstream links, so they don't need separate
mjr 82:4f6209cb5c33 342 // peripheral or software triggers.
mjr 82:4f6209cb5c33 343 adc_dma.trigger(Trigger_NONE);
mjr 82:4f6209cb5c33 344 clkDn_dma.trigger(Trigger_NONE);
mjr 82:4f6209cb5c33 345
mjr 82:4f6209cb5c33 346 // Register an interrupt callback so that we're notified when
mjr 82:4f6209cb5c33 347 // the last transfer completes.
mjr 82:4f6209cb5c33 348 clkDn_dma.attach(this, &TSL14xx::transferDone);
mjr 82:4f6209cb5c33 349
mjr 82:4f6209cb5c33 350 // clear the timing statistics
mjr 82:4f6209cb5c33 351 totalTime = 0.0;
mjr 82:4f6209cb5c33 352 nRuns = 0;
mjr 101:755f44622abc 353
mjr 101:755f44622abc 354 // start the first transfer
mjr 101:755f44622abc 355 startTransfer();
mjr 82:4f6209cb5c33 356 }
mjr 82:4f6209cb5c33 357
mjr 82:4f6209cb5c33 358 // Get the stable pixel array. This is the image array from the
mjr 82:4f6209cb5c33 359 // previous capture. It remains valid until the next startCapture()
mjr 82:4f6209cb5c33 360 // call, at which point this buffer will be reused for the new capture.
mjr 82:4f6209cb5c33 361 void getPix(uint8_t * &pix, uint32_t &t)
mjr 82:4f6209cb5c33 362 {
mjr 82:4f6209cb5c33 363 // return the pixel array that ISN'T assigned to the DMA
mjr 82:4f6209cb5c33 364 if (pixDMA)
mjr 82:4f6209cb5c33 365 {
mjr 82:4f6209cb5c33 366 // DMA owns pix2, so the stable array is pix1
mjr 82:4f6209cb5c33 367 pix = pix1;
mjr 82:4f6209cb5c33 368 t = t1;
mjr 82:4f6209cb5c33 369 }
mjr 82:4f6209cb5c33 370 else
mjr 82:4f6209cb5c33 371 {
mjr 82:4f6209cb5c33 372 // DMA owns pix1, so the stable array is pix2
mjr 82:4f6209cb5c33 373 pix = pix2;
mjr 82:4f6209cb5c33 374 t = t2;
mjr 82:4f6209cb5c33 375 }
mjr 82:4f6209cb5c33 376 }
mjr 82:4f6209cb5c33 377
mjr 86:e30a1f60f783 378 // Wait for the current DMA transfer to finish, and retrieve its
mjr 86:e30a1f60f783 379 // pixel array buffer. This provides access to the latest image
mjr 86:e30a1f60f783 380 // without starting a new transfer. These pixels are valid throughout
mjr 86:e30a1f60f783 381 // the next transfer (started via startCapture()) and remain valid
mjr 86:e30a1f60f783 382 // until the next transfer after that.
mjr 86:e30a1f60f783 383 void waitPix(uint8_t * &pix, uint32_t &t)
mjr 86:e30a1f60f783 384 {
mjr 101:755f44622abc 385 // wait for stable buffer ownership to transfer to the client
mjr 86:e30a1f60f783 386 wait();
mjr 86:e30a1f60f783 387
mjr 86:e30a1f60f783 388 // Return the pixel array that IS assigned to DMA, since this
mjr 86:e30a1f60f783 389 // is the latest buffer filled. This buffer is stable, even
mjr 86:e30a1f60f783 390 // though it's assigned to DMA, because the last transfer is
mjr 86:e30a1f60f783 391 // already finished and thus DMA is no longer accessing the
mjr 86:e30a1f60f783 392 // buffer.
mjr 86:e30a1f60f783 393 if (pixDMA)
mjr 86:e30a1f60f783 394 {
mjr 86:e30a1f60f783 395 // DMA owns pix2
mjr 86:e30a1f60f783 396 pix = pix2;
mjr 86:e30a1f60f783 397 t = t2;
mjr 86:e30a1f60f783 398 }
mjr 86:e30a1f60f783 399 else
mjr 86:e30a1f60f783 400 {
mjr 86:e30a1f60f783 401 // DMA owns pix1
mjr 86:e30a1f60f783 402 pix = pix1;
mjr 86:e30a1f60f783 403 t = t1;
mjr 86:e30a1f60f783 404 }
mjr 86:e30a1f60f783 405 }
mjr 86:e30a1f60f783 406
mjr 101:755f44622abc 407 // Set the requested minimum integration time. If this is less than the
mjr 101:755f44622abc 408 // sensor's physical minimum time, the physical minimum applies.
mjr 101:755f44622abc 409 virtual void setMinIntTime(uint32_t us)
mjr 82:4f6209cb5c33 410 {
mjr 101:755f44622abc 411 tIntMin = us;
mjr 101:755f44622abc 412 }
mjr 101:755f44622abc 413
mjr 101:755f44622abc 414 // Wait for the stable buffer ownership to transfer to the client
mjr 101:755f44622abc 415 void wait() { while (!clientOwnsStablePix) ; }
mjr 101:755f44622abc 416
mjr 101:755f44622abc 417 // Is a buffer available?
mjr 101:755f44622abc 418 bool ready() const { return clientOwnsStablePix; }
mjr 101:755f44622abc 419
mjr 101:755f44622abc 420 // Release the client DMA buffer. The client must call this when it's
mjr 101:755f44622abc 421 // done with the current image frame to release the frame back to the
mjr 101:755f44622abc 422 // DMA subsystem, so that it can hand us the next frame.
mjr 101:755f44622abc 423 void releasePix() { clientOwnsStablePix = false; }
mjr 82:4f6209cb5c33 424
mjr 101:755f44622abc 425 // get the timing statistics - sum of scan time for all scans so far
mjr 101:755f44622abc 426 // in microseconds, and total number of scans so far
mjr 101:755f44622abc 427 void getTimingStats(uint64_t &totalTime, uint32_t &nRuns) const
mjr 101:755f44622abc 428 {
mjr 101:755f44622abc 429 totalTime = this->totalTime;
mjr 101:755f44622abc 430 nRuns = this->nRuns;
mjr 101:755f44622abc 431 }
mjr 101:755f44622abc 432
mjr 101:755f44622abc 433 // get the average scan time in microseconds
mjr 101:755f44622abc 434 uint32_t getAvgScanTime() const
mjr 101:755f44622abc 435 {
mjr 101:755f44622abc 436 return uint32_t(totalTime / nRuns);
mjr 101:755f44622abc 437 }
mjr 101:755f44622abc 438
mjr 101:755f44622abc 439 private:
mjr 101:755f44622abc 440 // Start a new transfer. We call this at the end of each integration
mjr 101:755f44622abc 441 // cycle, in interrupt mode. This can be called directly by the interrupt
mjr 101:755f44622abc 442 // handler invoked when the DMA transfer completes, or by a timeout. In
mjr 101:755f44622abc 443 // either case, we're in interrupt mode.
mjr 101:755f44622abc 444 void startTransfer()
mjr 101:755f44622abc 445 {
mjr 101:755f44622abc 446 // If we own the stable buffer, swap buffers: hand ownership of the
mjr 101:755f44622abc 447 // old DMA buffer to the client, and take control of the old client
mjr 101:755f44622abc 448 // buffer (which the client must be done with if we own it) as our
mjr 101:755f44622abc 449 // new DMA buffer.
mjr 101:755f44622abc 450 //
mjr 101:755f44622abc 451 // If the client owns the stable buffer, we can't swap buffers,
mjr 101:755f44622abc 452 // because the client is still working on the stable one. So we
mjr 101:755f44622abc 453 // must start the new transfer using the existing DMA buffer.
mjr 101:755f44622abc 454 if (!clientOwnsStablePix)
mjr 82:4f6209cb5c33 455 {
mjr 101:755f44622abc 456 // swap buffers
mjr 101:755f44622abc 457 pixDMA ^= 1;
mjr 101:755f44622abc 458
mjr 101:755f44622abc 459 // release the prior DMA buffer to the client
mjr 101:755f44622abc 460 clientOwnsStablePix = true;
mjr 82:4f6209cb5c33 461 }
mjr 82:4f6209cb5c33 462
mjr 82:4f6209cb5c33 463 // Set up the active pixel array as the destination buffer for
mjr 82:4f6209cb5c33 464 // the ADC DMA channel.
mjr 82:4f6209cb5c33 465 adc_dma.destination(pixDMA ? pix2 : pix1, true);
mjr 82:4f6209cb5c33 466
mjr 82:4f6209cb5c33 467 // start the DMA transfers
mjr 82:4f6209cb5c33 468 clkDn_dma.start(nPixSensor*4, true);
mjr 82:4f6209cb5c33 469 adc_dma.start(nPixSensor, true);
mjr 82:4f6209cb5c33 470 clkUp_dma.start(nPixSensor*4, true);
mjr 82:4f6209cb5c33 471
mjr 82:4f6209cb5c33 472 // note the start time of this transfer
mjr 82:4f6209cb5c33 473 t0 = t.read_us();
mjr 82:4f6209cb5c33 474
mjr 82:4f6209cb5c33 475 // start the next integration cycle by pulsing SI and one clock
mjr 82:4f6209cb5c33 476 si = 1;
mjr 82:4f6209cb5c33 477 clock = 1;
mjr 82:4f6209cb5c33 478 si = 0;
mjr 82:4f6209cb5c33 479 clock = 0;
mjr 82:4f6209cb5c33 480
mjr 82:4f6209cb5c33 481 // Set the timestamp for the current active buffer. The SI pulse
mjr 86:e30a1f60f783 482 // we just did performed the HOLD operation, which takes a snapshot
mjr 86:e30a1f60f783 483 // of the photo receptors and stores it in the sensor's shift
mjr 86:e30a1f60f783 484 // register. We noted the start of the current integration cycle
mjr 86:e30a1f60f783 485 // in tInt when we started it during the previous scan. The image
mjr 86:e30a1f60f783 486 // we're about to transfer therefore represents the light collected
mjr 86:e30a1f60f783 487 // between tInt and right now (actually, the SI pulse above, but
mjr 86:e30a1f60f783 488 // close enough). The image covers a time range rather than a
mjr 86:e30a1f60f783 489 // single point in time, but we still have to give it a single
mjr 86:e30a1f60f783 490 // timestamp. Use the midpoint of the integration period.
mjr 82:4f6209cb5c33 491 uint32_t tmid = (t0 + tInt) >> 1;
mjr 82:4f6209cb5c33 492 if (pixDMA)
mjr 82:4f6209cb5c33 493 t2 = tmid;
mjr 82:4f6209cb5c33 494 else
mjr 82:4f6209cb5c33 495 t1 = tmid;
mjr 82:4f6209cb5c33 496
mjr 82:4f6209cb5c33 497 // Start the ADC sampler. The ADC will read samples continuously
mjr 82:4f6209cb5c33 498 // until we tell it to stop. Each sample completion will trigger
mjr 82:4f6209cb5c33 499 // our linked DMA channel, which will store the next sample in our
mjr 82:4f6209cb5c33 500 // pixel array and pulse the CCD serial data clock to load the next
mjr 82:4f6209cb5c33 501 // pixel onto the analog sampler pin. This will all happen without
mjr 82:4f6209cb5c33 502 // any CPU involvement, so we can continue with other work.
mjr 82:4f6209cb5c33 503 ao.start();
mjr 82:4f6209cb5c33 504
mjr 82:4f6209cb5c33 505 // The new integration cycle starts with the 19th clock pulse
mjr 82:4f6209cb5c33 506 // after the SI pulse. We offload all of the transfer work (including
mjr 86:e30a1f60f783 507 // the clock pulse generation) to the DMA controller, which doesn't
mjr 86:e30a1f60f783 508 // notify when that 19th pulse occurs, so we have to approximate.
mjr 86:e30a1f60f783 509 // Based on empirical measurements, each pixel transfer in our DMA
mjr 86:e30a1f60f783 510 // setup takes about 2us, so clocking 19 pixels takes about 38us.
mjr 86:e30a1f60f783 511 // In addition, the ADC takes about 4us extra for the first read.
mjr 86:e30a1f60f783 512 tInt = t.read_us() + 19*2 + 4;
mjr 82:4f6209cb5c33 513 }
mjr 82:4f6209cb5c33 514
mjr 101:755f44622abc 515 // End of transfer notification. This is called as an interrupt
mjr 101:755f44622abc 516 // handler when the DMA transfer completes.
mjr 101:755f44622abc 517 void transferDone()
mjr 82:4f6209cb5c33 518 {
mjr 101:755f44622abc 519 // stop the ADC sampler
mjr 101:755f44622abc 520 ao.stop();
mjr 101:755f44622abc 521
mjr 101:755f44622abc 522 // clock out one extra pixel to leave the analog out pin on
mjr 101:755f44622abc 523 // the sensor in the high-Z state
mjr 101:755f44622abc 524 clock = 1;
mjr 101:755f44622abc 525 clock = 0;
mjr 101:755f44622abc 526
mjr 101:755f44622abc 527 // add this sample to the timing statistics (for diagnostics and
mjr 101:755f44622abc 528 // performance measurement)
mjr 101:755f44622abc 529 uint32_t now = t.read_us();
mjr 101:755f44622abc 530 totalTime += uint32_t(now - t0);
mjr 101:755f44622abc 531 nRuns += 1;
mjr 101:755f44622abc 532
mjr 101:755f44622abc 533 // note the ending time of the transfer
mjr 101:755f44622abc 534 tDone = now;
mjr 101:755f44622abc 535
mjr 101:755f44622abc 536 // Figure the time remaining to reach the minimum requested
mjr 101:755f44622abc 537 // integration time for the next cycle. The sensor is currently
mjr 101:755f44622abc 538 // working on an integration cycle that started at tInt, and that
mjr 101:755f44622abc 539 // cycle will end when we start the next cycle. We therefore want
mjr 101:755f44622abc 540 // to wait to start the next cycle until we've reached the desired
mjr 101:755f44622abc 541 // total integration time.
mjr 101:755f44622abc 542 uint32_t dt = now - tInt;
mjr 101:755f44622abc 543 if (dt < tIntMin)
mjr 101:755f44622abc 544 {
mjr 101:755f44622abc 545 // more time is required - set a timeout for the remaining inteval
mjr 101:755f44622abc 546 integrationTimeout.attach_us(this, &TSL14xx::startTransfer, tIntMin - dt);
mjr 101:755f44622abc 547 }
mjr 101:755f44622abc 548 else
mjr 101:755f44622abc 549 {
mjr 101:755f44622abc 550 // we've already reached the minimum integration time - start
mjr 101:755f44622abc 551 // the next transfer immediately
mjr 101:755f44622abc 552 startTransfer();
mjr 101:755f44622abc 553 }
mjr 82:4f6209cb5c33 554 }
mjr 101:755f44622abc 555
mjr 101:755f44622abc 556 // Clear the sensor shift register. Clocks in all of the pixels from
mjr 101:755f44622abc 557 // the sensor without bothering to read them on the ADC. Pulses SI
mjr 101:755f44622abc 558 // at the beginning of the operation, which starts a new integration
mjr 101:755f44622abc 559 // cycle.
mjr 82:4f6209cb5c33 560 void clear()
mjr 82:4f6209cb5c33 561 {
mjr 82:4f6209cb5c33 562 // get the clock toggle register
mjr 82:4f6209cb5c33 563 volatile uint32_t *ptor = &clockPort->PTOR;
mjr 82:4f6209cb5c33 564
mjr 82:4f6209cb5c33 565 // make sure any DMA run is completed
mjr 82:4f6209cb5c33 566 wait();
mjr 82:4f6209cb5c33 567
mjr 82:4f6209cb5c33 568 // clock in an SI pulse
mjr 82:4f6209cb5c33 569 si = 1;
mjr 82:4f6209cb5c33 570 *ptor = clockMask;
mjr 82:4f6209cb5c33 571 clockPort->PSOR = clockMask;
mjr 82:4f6209cb5c33 572 si = 0;
mjr 82:4f6209cb5c33 573 *ptor = clockMask;
mjr 82:4f6209cb5c33 574
mjr 82:4f6209cb5c33 575 // This starts a new integration period. Or more precisely, the
mjr 82:4f6209cb5c33 576 // 19th clock pulse will start the new integration period. We're
mjr 82:4f6209cb5c33 577 // going to blast the clock signal as fast as we can, at about
mjr 82:4f6209cb5c33 578 // 100ns intervals (50ns up and 50ns down), so the 19th clock
mjr 82:4f6209cb5c33 579 // will be about 2us from now.
mjr 82:4f6209cb5c33 580 tInt = t.read_us() + 2;
mjr 82:4f6209cb5c33 581
mjr 82:4f6209cb5c33 582 // clock out all pixels, plus an extra one to clock past the last
mjr 82:4f6209cb5c33 583 // pixel and reset the last pixel's internal sampling switch in
mjr 82:4f6209cb5c33 584 // the sensor
mjr 82:4f6209cb5c33 585 for (int i = 0 ; i < nPixSensor + 1 ; )
mjr 82:4f6209cb5c33 586 {
mjr 82:4f6209cb5c33 587 // toggle the clock to take it high
mjr 82:4f6209cb5c33 588 *ptor = clockMask;
mjr 82:4f6209cb5c33 589
mjr 82:4f6209cb5c33 590 // increment our loop variable here to pad the timing, to
mjr 82:4f6209cb5c33 591 // keep our pulse width long enough for the sensor
mjr 82:4f6209cb5c33 592 ++i;
mjr 82:4f6209cb5c33 593
mjr 82:4f6209cb5c33 594 // toggle the clock to take it low
mjr 82:4f6209cb5c33 595 *ptor = clockMask;
mjr 82:4f6209cb5c33 596 }
mjr 82:4f6209cb5c33 597 }
mjr 86:e30a1f60f783 598
mjr 82:4f6209cb5c33 599 // DMA controller interfaces
mjr 82:4f6209cb5c33 600 SimpleDMA adc_dma; // DMA channel for reading the analog input
mjr 82:4f6209cb5c33 601 SimpleDMA clkUp_dma; // "Clock Up" channel
mjr 82:4f6209cb5c33 602 SimpleDMA clkDn_dma; // "Clock Down" channel
mjr 82:4f6209cb5c33 603
mjr 82:4f6209cb5c33 604 // Sensor interface pins
mjr 82:4f6209cb5c33 605 DigitalOut si; // GPIO pin for sensor SI (serial data)
mjr 82:4f6209cb5c33 606 DigitalOut clock; // GPIO pin for sensor SCLK (serial clock)
mjr 82:4f6209cb5c33 607 GPIO_Type *clockPort; // IOPORT base address for clock pin - cached for DMA writes
mjr 82:4f6209cb5c33 608 uint32_t clockMask; // IOPORT register bit mask for clock pin
mjr 100:1ff35c07217c 609 AltAnalogIn_8bit ao; // GPIO pin for sensor AO (analog output)
mjr 82:4f6209cb5c33 610
mjr 82:4f6209cb5c33 611 // number of pixels in the physical sensor array
mjr 82:4f6209cb5c33 612 int nPixSensor; // number of pixels in physical sensor array
mjr 82:4f6209cb5c33 613
mjr 82:4f6209cb5c33 614 // pixel buffers - we keep two buffers so that we can transfer the
mjr 82:4f6209cb5c33 615 // current sensor data into one buffer via DMA while we concurrently
mjr 82:4f6209cb5c33 616 // process the last buffer
mjr 82:4f6209cb5c33 617 uint8_t *pix1; // pixel array 1
mjr 82:4f6209cb5c33 618 uint8_t *pix2; // pixel array 2
mjr 82:4f6209cb5c33 619
mjr 82:4f6209cb5c33 620 // Timestamps of pix1 and pix2 arrays, in microseconds, in terms of the
mjr 100:1ff35c07217c 621 // sample timer (this->t).
mjr 82:4f6209cb5c33 622 uint32_t t1;
mjr 82:4f6209cb5c33 623 uint32_t t2;
mjr 82:4f6209cb5c33 624
mjr 82:4f6209cb5c33 625 // DMA target buffer. This is the buffer for the next DMA transfer.
mjr 82:4f6209cb5c33 626 // 0 means pix1, 1 means pix2. The other buffer contains the stable
mjr 82:4f6209cb5c33 627 // data from the last transfer.
mjr 82:4f6209cb5c33 628 uint8_t pixDMA;
mjr 82:4f6209cb5c33 629
mjr 101:755f44622abc 630 // Stable buffer ownership. At any given time, the DMA subsystem owns
mjr 101:755f44622abc 631 // the buffer specified by pixDMA. The other buffer - the "stable" buffer,
mjr 101:755f44622abc 632 // which contains the most recent completed frame, can be owned by EITHER
mjr 101:755f44622abc 633 // the client or by the DMA subsystem. Each time a DMA transfer completes,
mjr 101:755f44622abc 634 // the DMA subsystem looks at the stable buffer owner flag to determine
mjr 101:755f44622abc 635 // what to do:
mjr 101:755f44622abc 636 //
mjr 101:755f44622abc 637 // - If the DMA subsystem owns the stable buffer, it swaps buffers. This
mjr 101:755f44622abc 638 // makes the newly completed DMA buffer the new stable buffer, and makes
mjr 101:755f44622abc 639 // the old stable buffer the new DMA buffer. At this time, the DMA
mjr 101:755f44622abc 640 // subsystem also changes the stable buffer ownership to CLIENT.
mjr 101:755f44622abc 641 //
mjr 101:755f44622abc 642 // - If the CLIENT owns the stable buffer, the DMA subsystem can't swap
mjr 101:755f44622abc 643 // buffers, because the client is still using the stable buffer. It
mjr 101:755f44622abc 644 // simply leaves things as they are.
mjr 101:755f44622abc 645 //
mjr 101:755f44622abc 646 // In either case, the DMA system starts a new transfer at this point.
mjr 101:755f44622abc 647 //
mjr 101:755f44622abc 648 // The client, meanwhile, is free to access the stable buffer when it has
mjr 101:755f44622abc 649 // ownership. If the client *doesn't* have ownership, it must wait for
mjr 101:755f44622abc 650 // the ownership to be transferred, which can only be done by the DMA
mjr 101:755f44622abc 651 // subsystem on completing a transfer.
mjr 101:755f44622abc 652 //
mjr 101:755f44622abc 653 // When the client is done with the stable buffer, it transfers ownership
mjr 101:755f44622abc 654 // back to the DMA subsystem.
mjr 101:755f44622abc 655 //
mjr 101:755f44622abc 656 // Transfers of ownership from DMA to CLIENT are done only by DMA.
mjr 101:755f44622abc 657 // Transfers from CLIENT to DMA are done only by CLIENT. So whoever has
mjr 101:755f44622abc 658 // ownership now is responsible for transferring ownership.
mjr 101:755f44622abc 659 //
mjr 101:755f44622abc 660 volatile bool clientOwnsStablePix;
mjr 101:755f44622abc 661
mjr 101:755f44622abc 662 // End-of-integration timeout handler. This lets us fire an interrupt
mjr 101:755f44622abc 663 // when the current integration cycle is done, so that we can start the
mjr 101:755f44622abc 664 // next cycle.
mjr 101:755f44622abc 665 Timeout integrationTimeout;
mjr 101:755f44622abc 666
mjr 101:755f44622abc 667 // Requested minimum integration time, in micoseconds. The client can use
mjr 101:755f44622abc 668 // this to control the exposure level, by increasing it for a longer
mjr 101:755f44622abc 669 // exposure and thus more light-gathering in low-light conditions. Note
mjr 101:755f44622abc 670 // that the physical limit on the minimum integration time is roughly equal
mjr 101:755f44622abc 671 // to the pixel file transfer time, because the integration cycle is
mjr 101:755f44622abc 672 // initiated and ended by transfer starts. It's thus impossible to make
mjr 101:755f44622abc 673 // the integration time less than the time for one full pixel file
mjr 101:755f44622abc 674 // transfer.
mjr 101:755f44622abc 675 uint32_t tIntMin;
mjr 101:755f44622abc 676
mjr 82:4f6209cb5c33 677 // timing statistics
mjr 82:4f6209cb5c33 678 Timer t; // sample timer
mjr 82:4f6209cb5c33 679 uint32_t t0; // start time (us) of current sample
mjr 82:4f6209cb5c33 680 uint32_t tInt; // start time (us) of current integration period
mjr 86:e30a1f60f783 681 uint32_t tDone; // end time of latest finished transfer
mjr 82:4f6209cb5c33 682 uint64_t totalTime; // total time consumed by all reads so far
mjr 82:4f6209cb5c33 683 uint32_t nRuns; // number of runs so far
mjr 82:4f6209cb5c33 684 };
mjr 82:4f6209cb5c33 685
mjr 82:4f6209cb5c33 686 #endif /* TSL14XX_H */