Appendix: Serial Programming Interface; Introduction - Arcam AVP700 Handbook

Appendix: Serial programming interface

Introduction

This section describes the remote control protocol for controlling the AVP700 via the RS232 interface.
Conventions
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Data transfer format
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Command and response formats
Communication between the remote controller (RC) and the AVP700 takes the form of sequences of
ASCII characters, with all commands and responses having the same basic format. The AVP700 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>
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Each response by the AVP700 is eight bytes long with the following format:
<STR> <RC> <AC> <P1> <P2> <ETR>
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The AVP700 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:
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State changes as a result of other inputs
It is possible that the state of the AVP700 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
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_ *
Assuming that the command was accepted by the AVP700, the AVP700 shall respond to this command
with the following sequence:
STR RC AC P1 P2 ETR
AV_ *
All values in this section are hexadecimal values, unless otherwise specified.
Transfer rate: 38,400bps.
1 start bit, 8 data bits, 1 stop bit, no parity, no flow control.
STR (Start transmission): 0x50, 0x43, 0x5F ("PC_")
CC (Command code): the code for the command
Px (Parameter code): the parameters for the command
ETR (End transmission): 0xd
STR (Start transmission): 0x41, 0x56, 0x5f ("AV_")
RC (Reply code): = command code
AC (Answer code): answer code (see below)
Px (Parameter code): the parameters for the reponse
ETR (End transmission): 0xd
Command OK – 'P' (0x50): The command has been accepted and processed completely.
Command 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.
1 1 (0xd)
P 1 1 (0xd)
button on the
DISPLAY
AVP700
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