Monday, January 21, 2013

REMOTE CONTROL DETAILED

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Microsoft Windows Media Center uses infrared (IR) both for basic control of a computer and for controlling other IR-based devices that are used in conjunction with Windows Media Center. You should have a basic understanding of the IR functionality in Windows Media Center and how it is used with the software so that when you develop your hardware and port drivers you understand how the hardware and software will work together.The terms are important to know when you read this documentation:Main IR receiverA wide-band IR receiver that is used to receive IR commands from the Windows Media Center remote control and to translate those signals in order to interact with Windows Media Center.This receiver is used in the first run when the user is configuring a set-top box. The main IR receiver is used with the parse-and-match functionality to recognize a set-top box remote control.Learning IR receiverA close-range IR receiver that is used when Windows Media Center cannot correctly identify the set-top box remote control that is using parse-and-match. The user is then guided through a step-by-step process so that Windows Media Center "learns" the numeric keys on the remote control so it can control the set-top box.This receiver is used in the first run when the user is configuring a set-top box.IR outputSends IR signals from the computer to control a set-top box. The IR signals sent through the IR output port are sent from a licensed IR database or from a user IR database, if the user has gone through the IR learning process.IR output is important for any user that is trying to control a set-top box. There are two primary scenarios that are important to Windows Media Center:The user wants to record a show when they are not at home. Windows Media Center needs to be capable of changing the channel for the user.The user uses a Windows Media Center Extender in another room to watch television, and they want to change channels. The Windows Media Center computer needs to relay the command to the set-top box.Device configuration informationIdentifies the type of receiver that is connected to the system and displays the appropriate error messages to the user so they can set up their computer. This information is used in used in the first run. Microsoft Windows Media Center uses infrared (IR) both for basic control of a computer and for controlling other IR-based devices that are used in conjunction with Windows Media Center. You should have a basic understanding of the IR functionality in Windows Media Center and how it is used with the software so that when you develop your hardware and port drivers you understand how the hardware and software will work together.The terms are important to know when you read this documentation:Main IR receiverA wide-band IR receiver that is used to receive IR commands from the Windows Media Center remote control and to translate those signals in order to interact with Windows Media Center.This receiver is used in the first run when the user is configuring a set-top box. The main IR receiver is used with the parse-and-match functionality to recognize a set-top box remote control.Learning IR receiverA close-range IR receiver that is used when Windows Media Center cannot correctly identify the set-top box remote control that is using parse-and-match. The user is then guided through a step-by-step process so that Windows Media Center "learns" the numeric keys on the remote control so it can control the set-top box.This receiver is used in the first run when the user is configuring a set-top box.IR outputSends IR signals from the computer to control a set-top box. The IR signals sent through the IR output port are sent from a licensed IR database or from a user IR database, if the user has gone through the IR learning process.IR output is important for any user that is trying to control a set-top box. There are two primary scenarios that are important to Windows Media Center:The user wants to record a show when they are not at home. Windows Media Center needs to be capable of changing the channel for the user.The user uses a Windows Media Center Extender in another room to watch television, and they want to change channels. The Windows Media Center computer needs to relay the command to the set-top box.Device configuration informationIdentifies the type of receiver that is connected to the system and displays the appropriate error messages to the user so they can set up their computer. This information is used in used in the first run. Support for consumer infrared (CIR) remote controls is implemented in the Microsoft Windows operating systems by using a stack of drivers. Starting in Windows Vista, the architecture of this driver stack has been both extended and simplified to facilitate support of non-Microsoft CIR remote controls. The following diagram shows the overall architecture of the CIR driver stack.The preceding diagram shows the components that are used to support remote control operations in Windows. Components provided by Microsoft are shown as blue-shaded blocks; Windows Media Center partner-developed components are shown as white blocks. Both user-mode and kernel-mode components are illustrated.Support in the Windows operating system for CIR remote controls is anchored by the CIRClass driver. As shown in the preceding diagram, the upper edge of this driver provides the interface to the rest of the Windows system. As CIRClass receives data from underlying CIR Port drivers (such as USBCIR in the diagram), it routes that data (according to its own algorithms) to user-mode Windows Media Center components, to the human interface device (HID) stack, or to both of these destinations. During IR blasting operations, CIRClass sends data to one or more specific CIR Port drivers.The lower edge of CIRClass provides an interface to one or more CIR Port drivers, including the Microsoft-supplied USBCIR driver. CIR Port drivers are responsible for controlling their CIR remote control hardware and for translating data for that hardware between the standard format that CIRClass uses (see Data Format) and their hardware's proprietary format.The USBCIR driver supports standard Microsoft-defined CIR devices that connect to the computer through USB. USBCIR interfaces with CIRClass at its upper edge and with the standard Microsoft USB driver stack at its lower edge.Also, the preceding diagram shows how an arbitrary, non-Microsoft-developed CIR remote control fits into the Windows system of CIR support. Non-Microsoft CIR Port drivers interface with the standard CIRClass driver at their upper edge, and with their hardware at their lower edge. Note that the CIR Port driver can interact with its hardware directly or indirectly, through an additional set of drivers that Microsoft might supply. For example, a non-Microsoft CIR Port driver would directly interface with a PCI-based non-Microsoft CIR remote control (with the support of the standard Microsoft-supplied PCI bus driver). Alternatively, a non-Microsoft USB-based CIR remote control would interact with its device indirectly through the standard Microsoft-supplied USB driver stack. There are two types of remotes that you need to take into account: normal remotes and pulse-mode remotes:Normal remotes are modulated with a carrier and have pulse widths from 50-5000 microseconds. Information is typically conveyed with the relative lengths of pulses and spaces. Normal remotes account for about 95 percent of the remote controls in the world.Pulse-mode remotes are not modulated with a carrier. They have pulses from 4-45 microseconds. For a given remote code set, all pulses are http://msdn.microsoft.com/en-us/library/windows/hardware/ff557557(v=vs.85).aspx of identical width and the information is conveyed with the relative lengths of the spaces only. Pulse mode remotes account for about 5 percent of the remotes in the world.Your hardware should be able to emit IR for modulated code sets; however, we recommend supporting pulse-mode code sets. If your hardware supports pulse mode and the TRANSMIT_FLAGS_PULSE_MODE flag is set, your hardware needs to switch to pulse mode for emitting that IR.For receiving, your hardware does not need to do anything special for pulse mode.

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