Appendix: Serial programming interface

Introduction

This section describes the remote control protocol for controlling the AVR250 via the RS232 interface.

Conventions

nAll values in this section are hexadecimal values, unless otherwise specified.

Data transfer format

nTransfer rate: 38,400bps.

n1 start bit, 8 data bits, 1 stop bit, no parity, no flow control.

Command and response formats

Communication between the remote controller (RC) and the AVR250 takes the form of sequences of ASCII characters, with all commands and responses having the same basic format. The AVR250 shall always respond to a received command, but may also send messages at other times (i.e., full-duplex communication).

Each transmission by the RC is seven bytes long with the following format: <STR> <CC> <P1> <P2> <ETR>

nSTR (Start transmission): 0x50, 0x43, 0x5F (“PC_”)

nCC (Command code): the code for the command

nPx (Parameter code): the parameters for the command

nETR (End transmission): 0xd

Each response by the AVR250 is eight bytes long with the following format: <STR> <RC> <AC> <P1> <P2> <ETR>

nSTR (Start transmission): 0x41, 0x56, 0x5f (“AV_”)

nRC (Reply code): = command code

nAC (Answer code): answer code (see below)

nPx (Parameter code): the parameters for the reponse

nETR (End transmission): 0xd

The AVR250 responds to each command from the RC within three seconds. The RC may send further commands before a previous command response has been received.

Answer codes

The following answer codes are defined:

nCommand OK – ‘P’ (0x50): The command has been accepted and processed completely.

nCommand Error – ‘R’ (0x52): An error occurred relating to the command received. This may be either an invalid command (at this time), or a command formatting error.

State changes as a result of other inputs

It is possible that the state of the AVR250 may be changed as a result of user input via the front panel buttons or via the IR remote control. Changes resulting from these inputs is relayed to the RC using the appropriate message type.

For example, if the user changed the front panel display brightness using the DISPLAY button on the front panel, a display message (defined below) would be sent to the RC. A similar action would be taken for all other state changes (including decode mode changes).

Example command and response sequence

As an example, the command to be sent to bring the main zone out of stand-by (defined below) is as follows:

STR CC P1 P2 ETR

PC_ * 1 1 (0xd)

Assuming that the command was accepted by the AVR250, the AVR250 shall respond to this command with the following sequence:

STR RC AC P1 P2 ETR

AV_ * P 1 1 (0xd)

AVR250

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Arcam AVR250 manual Appendix Serial programming interface, Command and response formats
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AVR250 specifications

The Arcam AVR250 is a distinguished model in the realm of home theater receivers, embodying high-performance audio and video processing capabilities that cater to discerning audiophiles and home cinema enthusiasts alike. Designed by Arcam, a company renowned for its commitment to delivering premium sound, the AVR250 stands out through its thoughtful engineering and robust feature set.

At the heart of the AVR250 lies a powerful amplification stage capable of delivering a peak output of 100 watts per channel into 8 ohms, ensuring that even the most demanding speakers can be driven with ease. This level of power translates into dynamic audio experiences, whether you're enjoying your favorite movies, music, or gaming. The receiver also incorporates a sophisticated digital signal processing engine that enhances sound quality and ensures accurate reproduction of all audio formats.

One of the standout features of the AVR250 is its support for multiple surround sound formats, including Dolby Digital, DTS, and Dolby Pro Logic II. This enables users to experience surround sound in its full glory, bringing their favorite films to life with immersive audio tracks that add depth and realism to the viewing experience. The AVR250 also boasts an array of connectivity options, including HDMI inputs that support high-definition video and audio signals, allowing seamless integration with modern multimedia devices such as Blu-ray players, gaming consoles, and streaming devices.

In addition to its robust audio capabilities, the Arcam AVR250 is also equipped with video processing technologies. It can upscale standard definition content to high-definition resolution, ensuring that older media looks sharper and more vibrant on modern displays. The receiver also features video switching capabilities, allowing users to connect multiple video sources and effortlessly switch between them.

User-friendliness is another hallmark of the AVR250, featuring an intuitive on-screen display and remote control that make setup and operation straightforward. The receiver also offers advanced room correction technologies, which utilize microphone measurements to optimize sound performance in various room acoustics. This ensures that audiences receive the best possible sound quality tailored to their specific environment.

In summary, the Arcam AVR250 exemplifies a blend of power, quality, and versatility. With its advanced audio technologies, comprehensive connectivity options, and user-friendly design, this home theater receiver is poised to elevate cinematic experiences and music reproduction in any home. Whether you are an audiophile or a casual viewer, the AVR250 caters to a wide array of listening preferences, making it a worthy addition to any audio setup.
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