Specifications

Remote Control and Receiver-Transceiver Specifications and Requirements
for Windows Media Center in Windows Operating Systems
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The version 2 emulation interface adds additional capabilities bits, which allow a wider range of
devices, such as ―blast only‖, ―learn only‖, and so on. See CMD_GET_DEVDETAILS and
RSP_EQ_DEVDETAILS for more information.
Carrier Capture
When using the wide-band receiver, the device firmware must return the carrier count for any
particular sample. This carrier is an approximate value and applies to an entire sample. It is not
necessary to return an instantaneous carrier value. So, for instance, if the software is using the
wide-band receiver and asks the user to press the zero key, the firmware would send the RLC for
the envelope up to the software, and then send the value of the carrier frequency for the entire
key-press to the software.
The carrier information is sent from the firmware to the software as the ―duration that the signal
was high.‖ Details are in the response topic RSP_EQIRRXCFCNT, later in this document.
USB 1.1 Devices
You can build an emulator device that is a Full Speed USB 1.1 device. For Full Speed devices,
there is very little difference between USB 1.1 and USB 2.0. To make this work, you can have a
Full Speed USB 1.1 chip, but the firmware must follow two rules that are newer for USB 2.0:
 You must set bcdUSB to 0x0200 in the Device Descriptor. If the value of bcdUSB is hard-coded
to a different value in your USB chip, you cannot use that chip.
 You must respond correctly to the device_qualifier request. (For more information, see the
comment that follows regarding Section 9.6.1 of the USB 2.0 specification.)
The 2.0 specification adds a third device-implementation choice, High-Speed, to the Full-Speed
and Low-Speed device implementation choices. It does not eliminate the Full-Speed and Low-
Speed device choices. A device can claim it is compliant with the 2.0 specification even if it is a
Full-Speed or Low-Speed only device.
A USB 2.0 compliant device that is Full-Speed only is essentially the same as a USB 1.1
compliant device.
Section 9.6.1 of the USB 2.0 specification says this:
The DEVICE descriptor of a high-speed capable device has a version number of 2.0 (0200H). If
the device is full-speed only or low-speed only, this version number indicates that it will respond
correctly to a request for the device_qualifier descriptor (that is, it will respond with a request
error).
This means that if a Full-Speed only or Low-Speed only device returns a Device Descriptor with
bcdUSB set to 0x0200, it should be prepared to receive a Get Descriptor request for a Device
Qualifier Descriptor (see section 9.6.2 in the USB 2.0 specification) and if it receives this request,
it should respond to this request with a Request Error, that is, a STALL. (See section 9.2.7 in the
USB 2.0 specification.)
Modulated IR Protocol
 In modulated protocols, the IR signal is modulated with a carrier, typically around 30-60 KHz. The
information in a given data packet is determined by the width of the pulses in the envelope (pulse
width encoding), the width of the space between pulses in the envelope (space encoding), or the
timing of edges in the envelope (bi-phase or Manchester encoding). Pulse and space widths in