Drivers Motion Input Devices

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Open Windows Settings - Devices - Add Bluetooth or other device - Bluetooth and remove any earlier instances of “Motion controller – Right” and “Motion controller – Left”. Check also Other devices category at the bottom of the list. Select Add Bluetooth or other device and see it starting to discover Bluetooth devices. Latest Drivers in Input Devices. Intel Wireless Bluetooth Driver 22.20.0. Leap Motion Controller Driver and Software for Windows 2.3.1 With a wave of a hand or lift of a finger, you’re about. The package provides the installation files for Microsoft USB Input Device Driver version 10.0.4. If the driver is already installed on your system, updating (overwrite-installing) may fix various issues, add new functions, or just upgrade to the available version.

Application programs rely on a combination of user-mode and kernel-mode components to capture (input) and render (output) wave streams. A wave stream is a digital-audio stream whose data format is described by a WAVEFORMATEX or WAVEFORMATEXTENSIBLEMobile stream network tv. structure.

An application can use either of the following software interfaces for wave rendering and capture:

  • Microsoft Windows Multimedia waveOutXxx and waveInXxx functions

  • DirectSound and DirectSoundCapture APIs

The behavior of the waveOutXxx and waveInXxx functions is based on the capabilities of legacy wave drivers and devices. Beginning with Windows 98, the WDMAud system driver translates calls to these functions into commands to WDM audio drivers. However, by emulating the behavior of older software and hardware, the waveOutXxx functions sacrifice the 3-D sound effects and hardware acceleration that are now available through the DirectSound API. For more information about DirectSound and the Windows Multimedia wave functions, see the Microsoft Windows SDK documentation.

DirectSound and the Windows Multimedia wave functions are clients of the SysAudio system driver, which builds the audio filter graphs that process the wave and DirectSound streams. Graph building is transparent to the applications that use these software interfaces.

Wave Components

The following figure shows the user-mode and kernel-mode components that a wave application uses to render or capture a digital audio stream consisting of wave PCM data.

The rendering components appear on the left side of the preceding figure, and the capture components appear on the right. The boxes representing the wave miniport driver are darkened to indicate that these are vendor-supplied components. The other components in the figure are system-supplied.

At the top left of the figure, the wave-rendering (or 'wave-out') application interfaces to the WDM audio drivers through the waveOutXxx functions, which are implemented in the user-mode WinMM system component, Winmm.dll. The application reads blocks of wave audio samples from a file and calls the waveOutWrite function to render them.

WDMAud, which consists of both user-mode and kernel-mode components (Wdmaud.drv and Wdmaud.sys), buffers the wave data from the waveOutWrite call and outputs the wave stream to the KMixer system driver, which appears below WDMAud in the figure.

KMixer is a system component that receives wave PCM streams from one or more sources and mixes them together to form a single output stream, which is also in wave PCM format.

KMixer outputs a wave stream to a WaveCyclic or WavePci device, whose port and miniport drivers appear below KMixer on the left side of the preceding figure. The miniport driver binds itself to the port driver to form the wave filter that represents the underlying audio rendering device. A typical rendering device outputs an analog signal that drives a set of speakers or an external audio unit. A rendering device might also output digital audio through an S/PDIF connector. For more information about WaveCyclic and WavePci, see Wave Filters.

Alternatively, KMixer can pass its output stream to a USB audio device, which is controlled by the USBAudio class system driver (not shown in figure), instead of a WaveCyclic or WavePci device.

An adapter driver creates an instance of a WaveCyclic or WavePci port driver by calling PcNewPort with a GUID value of CLSID_PortWaveCyclic or CLSID_PortWavePci, respectively.

The right side of the preceding figure shows the components that are needed to support an application that captures wave data to a file. The wave-capture (or 'wave-in') application communicates with the WDM audio drivers through the waveInXxx functions, which are implemented in the WinMM system component.

At the lower right corner of the figure, the wave-capture device is controlled by wave miniport and port drivers. The port and miniport drivers, which can be of type WaveCyclic or WavePci, bind together to form a wave filter that represents the capture device. This device typically captures an analog signal from a microphone or other audio source and converts it to a wave PCM stream. The device might also input a digital audio stream through an S/PDIF connector.

Drivers Motion Input Devices Diagram

Drivers Motion Input Devices

The wave port driver outputs its wave stream either to KMixer or to WDMAud directly. The stream must pass through KMixer if it needs to be sample-rate converted before WDMAud receives it. A system that performs simultaneous rendering and capture of audio streams might require two instances of KMixer, as shown in the figure. Note that SysAudio automatically creates these instances as they are needed.

Alternatively, the source of the captured wave stream can be a USB audio device instead of a WaveCyclic or WavePci device. In this case, the USBAudio driver (not shown in figure) passes the stream to KMixer.

Regardless of whether the wave stream is captured by a USB device or by a WaveCyclic or WavePci device, KMixer performs sample-rate conversion on the stream, if needed, but does no mixing with other streams. KMixer outputs the resulting stream to Wdmaud.sys, the kernel-mode half of the WDMAud system driver. The user-mode half, Wdmaud.drv, outputs the wave stream to the application program through the waveInXxx functions, which are implemented in Winmm.dll. Finally, at the top of the figure, the wave-capture application writes the wave data to a file.

At the time that the wave-capture application calls the waveInOpen function to open the capture stream, it passes in a pointer to its callback routine. When a wave-capture event occurs, the operating system calls the callback routine with a buffer containing the next block of wave samples from the capture device. In response to the callback, the application writes the next block of wave data to the file.

DirectSound Components

Motion

The following figure shows the user-mode and kernel-mode components that are used by a DirectSound application program to render or capture wave data.

The rendering components are shown in the left half of the preceding figure, and the capture components appear on the right. The wave miniport drivers are shown as darkened boxes to indicate that they are vendor-supplied components. The other components in the figure are system-supplied.

At the top left of the figure, a DirectSound application loads wave data from a file to a sound buffer that the user-mode DirectSound system component (Dsound.dll) manages. This component sends a wave stream to a WaveCyclic or WavePci device, whose port and miniport drivers appear at the lower left in the figure. If a hardware mixer pin is available on the device, the stream passes directly to the wave port driver, bypassing KMixer. Otherwise, the stream first passes through KMixer, which mixes it with any other simultaneously playing streams. KMixer outputs the mixed stream to the port driver.

As before, the miniport driver binds itself to the port driver to form the wave filter that represents the underlying audio rendering device. This device might play the stream through a set of speakers, for example.

Alternatively, the wave stream can be rendered by a USB audio device instead of a WaveCyclic or WavePci device. In this case, the stream cannot bypass KMixer; the USBAudio class system driver (not shown in figure) always passes the stream to KMixer.

The right side of the preceding figure shows the components that support a DirectSoundCapture application. The application records wave data that is receives from a WaveCyclic or WavePci capture device. This device converts an analog signal from a microphone, for example, to a wave stream. The device's wave port and miniport drivers appear at the lower-right corner of the figure. As shown in the figure, the port driver receives as input the stream from the miniport driver and outputs it either directly to the user-mode DirectSound component, Dsound.dll, or indirectly through KMixer. This depends on whether a hardware capture pin is available from the capture device.

Alternatively, the source of the captured wave stream can be a USB audio device. In this case, the stream cannot bypass KMixer; the USBAudio driver (not shown in figure) always passes the stream to KMixer.

If KMixer is inserted into the path of the capture stream, it performs sample-rate conversion on the stream, if needed, but does no mixing with other streams.

At the top-right corner of the preceding figure, the application reads the wave data from the DirectSoundCapture buffer and writes it to the file.

1.1. The simplest example¶

Here comes a very simple example of an input device driver. The device hasjust one button and the button is accessible at i/o port BUTTON_PORT. Whenpressed or released a BUTTON_IRQ happens. The driver could look like:

1.2. What the example does¶

First it has to include the <linux/input.h> file, which interfaces to theinput subsystem. This provides all the definitions needed.

In the _init function, which is called either upon module load or whenbooting the kernel, it grabs the required resources (it should also checkfor the presence of the device).

Then it allocates a new input device structure with input_allocate_device()and sets up input bitfields. This way the device driver tells the otherparts of the input systems what it is - what events can be generated oraccepted by this input device. Our example device can only generate EV_KEYtype events, and from those only BTN_0 event code. Thus we only set thesetwo bits. We could have used:

as well, but with more than single bits the first approach tends to beshorter.

Then the example driver registers the input device structure by calling:

This adds the button_dev structure to linked lists of the input driver andcalls device handler modules _connect functions to tell them a new inputdevice has appeared. input_register_device() may sleep and therefore mustnot be called from an interrupt or with a spinlock held.

While in use, the only used function of the driver is:

which upon every interrupt from the button checks its state and reports itvia the:

call to the input system. There is no need to check whether the interruptroutine isn’t reporting two same value events (press, press for example) tothe input system, because the input_report_* functions check thatthemselves.

Then there is the:

call to tell those who receive the events that we’ve sent a complete report.This doesn’t seem important in the one button case, but is quite importantfor for example mouse movement, where you don’t want the X and Y valuesto be interpreted separately, because that’d result in a different movement.

Drivers Motion Input Devices For Sale

1.3. dev->open() and dev->close()¶

In case the driver has to repeatedly poll the device, because it doesn’thave an interrupt coming from it and the polling is too expensive to be doneall the time, or if the device uses a valuable resource (eg. interrupt), itcan use the open and close callback to know when it can stop polling orrelease the interrupt and when it must resume polling or grab the interruptagain. To do that, we would add this to our example driver:

Note that input core keeps track of number of users for the device andmakes sure that dev->open() is called only when the first user connectsto the device and that dev->close() is called when the very last userdisconnects. Calls to both callbacks are serialized.

The open() callback should return a 0 in case of success or any nonzero valuein case of failure. The close() callback (which is void) must always succeed.

1.4. Basic event types¶

The most simple event type is EV_KEY, which is used for keys and buttons.It’s reported to the input system via:

See uapi/linux/input-event-codes.h for the allowable values of code (from 0 toKEY_MAX). Value is interpreted as a truth value, ie any nonzero value means keypressed, zero value means key released. The input code generates events onlyin case the value is different from before.

Drivers Motion Input Devices

In addition to EV_KEY, there are two more basic event types: EV_REL andEV_ABS. They are used for relative and absolute values supplied by thedevice. A relative value may be for example a mouse movement in the X axis.The mouse reports it as a relative difference from the last position,because it doesn’t have any absolute coordinate system to work in. Absoluteevents are namely for joysticks and digitizers - devices that do work in anabsolute coordinate systems.

Having the device report EV_REL buttons is as simple as with EV_KEY, simplyset the corresponding bits and call the:

function. Events are generated only for nonzero value.

However EV_ABS requires a little special care. Before callinginput_register_device, you have to fill additional fields in the input_devstruct for each absolute axis your device has. If our button device had alsothe ABS_X axis:

Or, you can just say:

This setting would be appropriate for a joystick X axis, with the minimum of0, maximum of 255 (which the joystick must be able to reach, no problem ifit sometimes reports more, but it must be able to always reach the min andmax values), with noise in the data up to +- 4, and with a center flatposition of size 8.

If you don’t need absfuzz and absflat, you can set them to zero, which meanthat the thing is precise and always returns to exactly the center position(if it has any).

1.5. BITS_TO_LONGS(), BIT_WORD(), BIT_MASK()¶

These three macros from bitops.h help some bitfield computations:

1.6. The id* and name fields¶

The dev->name should be set before registering the input device by the inputdevice driver. It’s a string like ‘Generic button device’ containing auser friendly name of the device.

The id* fields contain the bus ID (PCI, USB, ..), vendor ID and device IDof the device. The bus IDs are defined in input.h. The vendor and device idsare defined in pci_ids.h, usb_ids.h and similar include files. These fieldsshould be set by the input device driver before registering it.

Drivers

The idtype field can be used for specific information for the input devicedriver.

The id and name fields can be passed to userland via the evdev interface.

1.7. The keycode, keycodemax, keycodesize fields¶

These three fields should be used by input devices that have dense keymaps.The keycode is an array used to map from scancodes to input system keycodes.The keycode max should contain the size of the array and keycodesize thesize of each entry in it (in bytes).

Drivers Motion Input Devices Pdf

Userspace can query and alter current scancode to keycode mappings usingEVIOCGKEYCODE and EVIOCSKEYCODE ioctls on corresponding evdev interface.When a device has all 3 aforementioned fields filled in, the driver mayrely on kernel’s default implementation of setting and querying keycodemappings.

1.8. dev->getkeycode() and dev->setkeycode()¶

getkeycode() and setkeycode() callbacks allow drivers to override defaultkeycode/keycodesize/keycodemax mapping mechanism provided by input coreand implement sparse keycode maps.

1.9. Key autorepeat¶

.. is simple. It is handled by the input.c module. Hardware autorepeat isnot used, because it’s not present in many devices and even where it ispresent, it is broken sometimes (at keyboards: Toshiba notebooks). To enableautorepeat for your device, just set EV_REP in dev->evbit. All will behandled by the input system.

Drivers Motion Input Devices Definition

1.10. Other event types, handling output events¶

Drivers motion input devices pdf

The other event types up to now are:

  • EV_LED - used for the keyboard LEDs.
  • EV_SND - used for keyboard beeps.

They are very similar to for example key events, but they go in the otherdirection - from the system to the input device driver. If your input devicedriver can handle these events, it has to set the respective bits in evbit,and also the callback routine:

Devices

This callback routine can be called from an interrupt or a BH (although thatisn’t a rule), and thus must not sleep, and must not take too long to finish.