Biamp SPM522D RS-232 User Manual

RS-232 Control

of the

Advantage SPM522D

________________________________________________________________________________________

Biamp Systems, 14130 N.W. Science Park, Portland, Oregon 97229 U.S.A. [phone]

an affiliate of Rauland-Borg Corp.

Introduction

This document contains technical information relating to computer control of the Biamp
Advantage SPM522D Stereo Preamp/Mixer. This information is intended for advanced
users - in particular for those who wish to develop their own computer programs to
control the SPM522D. It is assumed that the reader is an experienced programmer and
has some familiarity with standard programming practices, binary and hexadecimal
numbers, the ASCII character set, asynchronous serial data communications, and RS-232
interfaces.

Hexadecimal, ASCII-Hex, and "Pseudo-Hex" Numbers

Throughout this document, hexadecimal numbers shall be represented by preceding the
number with "0x". For example: the hexadecimal equivalent of the decimal number 255
is 0xFF.

Individual ASCII characters, except control characters, will be enclosed in single quotes.
For example: the ASCII character 'A' has the hexadecimal value 0x41. The ASCII
"carriage return" control character shall be represented as . An ASCII code chart is
included with this document for your convenience.

When an 8-bit binary data value is being transmitted over a serial data communications
link, it is a common practice to transmit the byte as two "ASCII-hex" characters - one
character represents the most significant nibble of the data value and the other character
represents the least significant nibble (a nibble is 4-bits; half of a byte). Each ASCII-hex
character is in the range of '0' thru '9' or 'A' thru 'F' (from the ASCII code chart, 0x30 thru
0x39 or 0x41 thru 0x46). For example, the hexadecimal equivalent of the decimal
number 61 is 0x3D. To transmit this in an ASCII-hex format, first transmit the ASCII
character '3' (whose hex value is 0x33), followed by the ASCII character 'D' (whose hex
value is 0x44). This is the standard way to transmit an ASCII-hex value. In some cases,
the lower case characters 'a' thru 'f' (0x61 thru 0x66) are accepted in addition to the upper
case letters 'A' thru 'F'.

The Advantage SPM522D does not utilize standard ASCII-hex format. The SPM522D
computer commands implement what I call "pseudo-hex" notation (also sometimes
referred to as a "poor man's" ASCII-hex notation). Instead of representing the
hexadecimal value using the ASCII characters '0' thru '9' and 'A', 'B', 'C', 'D', 'E', and 'F',
the pseudo-hex format uses the ASCII characters '0' thru '9' and the characters ':', ';', '<',
'=', '>', and '?'. As you can see by studying the ASCII code chart, a binary nibble may be
converted to its equivalent pseudo-hex character by simply adding 0x30.

A binary/decimal/hexadecimal/pseudo-hex conversion chart is included at the end of this
manual for your convenience.

Computer Control of the Advantage SPM522D page 1

Serial Interface - Data Communications Parameters

The SPM522D communicates through its serial interface at a data rate ("baud" rate) of
2400 bits per second with 8 data bits, 1 stop bit, and no parity. Although this is currently
the only supported data rate, 9600 bits per second may be supported in the future - contact
the factory for details. The SPM522D utilizes a subset of the standard 7-bit ASCII
character set. The eighth data bit (bit 7 - the most significant bit) of each character
transmitted by the computer should always be 0. The computer should not echo the
characters it receives from the SPM522D.

Since the SPM522D only has a single-character input buffer for its incoming serial data, a
form of flow control must be implemented by the computer in order to guarantee that no
characters are lost. Neither hardware (DTR) nor XON/XOFF (also known as DC1/DC3
or control-S/control-Q) handshaking is supported by the SPM522D. However, each
character which the SPM522D receives will be "echoed" back to the computer through
the SPM522D's serial interface. Flow control may be implemented by the computer
software by simply waiting for each character's echo from the SPM522D before
transmitting the next character, since the SPM522D doesn't retrieve and echo an
incoming character until it has finished processing the previous character.

Computer Control

The Advantage SPM522D has an RS-232-compatible serial interface which allows it to
be controlled by a computer. The SPM522D offers two methods of computer control:

 Control Button Emulation. This method of computer control allows the computer to

emulate Biamp's standard infrared remote control transmitter or wall-mount remote
control panel. Using this method, the computer outputs ASCII characters which are
equivalent to the characters generated by the remote control. Control Button
Emulation is simple to perform, however, it only provides "one-way" control of the
SPM522D - it allows the computer to send simple commands to the SPM522D, but it
does not provide any mechanism for requesting status information from the
SPM522D.

 Advanced Computer Control. This method of computer control provides advanced

commands which allow "two-way" control of the SPM522D. Using Advanced
Computer Control commands, the computer may request status information from the
device as well as send commands to the device. Advanced Computer Control and
Control Button Emulation are not mutually exclusive - both methods may be freely
intermixed.

page 2 Computer Control of the Advantage SPM522D

Control Button Emulation

Control Button Emulation is the simplest form of computer control of the Advantage
SPM522D. This method of operation allows the computer to emulate the operation of a
standard Biamp remote control transmitter.

The SPM522D provides two rear-panel remote control ports plus a remote translator port
in addition to the internal front-panel infrared receiver. The signals from these four
inputs are routed to a proprietary infrared decoder IC for translation before being sent on
to the SPM522D's main microprocessor. When the decoder IC detects a proper bitstream
which indicates that a button is being pressed on one of the remote control devices, it
converts the button code into a standard ASCII character and transmits it to the main
microprocessor's serial port. This is a shared serial port - the same serial port which is
used for computer control. When the microprocessor receives a character through its
serial port, it doesn't know (and doesn't care) whether that character came from a remote
control device or whether it came from the computer. So, in order for the computer to
emulate the operation of a remote control transmitter, all it has to do is transmit the same
ASCII characters that the decoder IC transmits for each detected button press.

The following table summarizes the ASCII characters corresponding to each of the 40
remote control buttons supported by the SPM522D. These button codes are also
summarized on the ASCII code chart provided at the end of this manual. The Advantage
PC Control Software Package also indicates on its button definition screen the equivalent
ASCII character for each of the 40 individual remote control buttons. The remote control
buttons on the standard Biamp transmitter are numbered from left to right going from
bottom to top with the lower left-hand button being button number 1.

Control Button Equivalent ASCII Codes (with factory default button definitions shown)

button 1 'B' (0x42) Mic 1 volume down
button 2 'C' (0x43) Mic 2 volume down
button 3 'D' (0x44) Zone volume down
button 4 'E' (0x45) Main volume down
button 5 'F' (0x46) Mic 1 volume up
button 6 'G' (0x47) Mic 2 volume up
button 7 'H' (0x48) Zone volume up
button 8 'I' (0x49) Main volume up
button 9 'J' (0x4A) Mic 1 toggle mute
button 10 'K' (0x4B) Mic 2 toggle mute
button 11 'L' (0x4C) Zone toggle mute
button 12 'M' (0x4D) Main toggle mute
button 13 'N' (0x4E) Zone recall preset E
button 14 'O' (0x4F) Zone recall preset F
button 15 'P' (0x50) Zone recall preset G
button 16 'Q' (0x51) Zone select source 5
button 17 'R' (0x52) Zone select source 1
button 18 'S' (0x53) Zone select source 2
button 19 'T' (0x54) Zone select source 3
button 20 'U' (0x55) Zone select source 4

button 21 'V' (0x56) Main recall preset A
button 22 'W' (0x57) Main recall preset B
button 23 'X' (0x58) Main recall preset C
button 24 'Y' (0x59) Main select source 5
button 25 'Z' (0x5A) Main select source 1
button 26 '[' (0x5B) Main select source 2
button 27 '\' (0x5C) Main select source 3
button 28 ']' (0x5D) Main select source 4
button 29 '^' (0x5E) NOP (no operation)
button 30 '_' (0x5F) NOP (no operation)
button 31 '`' (0x60) NOP (no operation)
button 32 'b' (0x62) NOP (no operation)
button 33 'c' (0x63) NOP (no operation)
button 34 'd' (0x64) NOP (no operation)
button 35 'e' (0x65) NOP (no operation)
button 36 'f' (0x66) NOP (no operation)
button 37 'g' (0x67) NOP (no operation)
button 38 'h' (0x68) NOP (no operation)
button 39 'i' (0x69) NOP (no operation)
button 40 'j' (0x6A) NOP (no operation)

When a remote control button is first pressed, the decoder IC sends the character which
corresponds to that button to the SPM522D's main microprocessor. If the button is

Computer Control of the Advantage SPM522D page 3

pressed for longer than 110 milliseconds, the decoder IC will then send a "repeat code" to
the main microprocessor and will continue to send additional repeat codes every 110
milliseconds for as long as the button is being pressed. The ASCII character
corresponding to the repeat code is '@' (0x40).

Device Select Prefix Characters

When using Advanced Computer Control, up to eight SPM522Ds may be linked together
and individually controlled by the computer (if each device is first assigned a unique
device number). When using Control Button Emulation, a limited subset of device
addressing may be performed, which allows individual control of up to four SPM522Ds
(with device numbers 1 thru 4). This is accomplished by transmitting a device select
prefix code immediately prior to each control button ASCII character code. The device
select prefix code is inspected by each device to determine whether or not the device
should react to the button code which immediately follows. (Note: do not transmit prefix
codes prior to repeat codes.) If a button code is not immediately preceded by a device
select prefix character, then all SPM522Ds in the system will react to that button code.
The following table summarizes the ASCII characters to use for selecting various devices.
This information is also summarized in the ASCII code chart provided at the end of this
manual.

Device Select Prefix Codes

select device 1 'l' (0x6C)
select device 2 'm' (0x6D)
select devices 1 & 2 'n' (0x6E)
select device 3 'o' (0x6F)
select devices 1 & 3 'p' (0x70)
select devices 2 & 3 'q' (0X71)
select devices 1 & 2 & 3 'r' (0x72)
select device 4 's' (0x73)
select devices 1 & 4 't' (0x74)
select devices 2 & 4 'u' (0x75)
select devices 1 & 2 & 4 'v' (0x76)
select devices 3 & 4 'w' (0x77)
select devices 1 & 3 & 4 'x' (0x78)
select devices 2 & 3 & 4 'y' (0x79)
select devices 1 & 2 & 3 & 4 'z' (0x7A)

Note: Device select prefix codes are not supported (and will be ignored) by SPM522Ds
with firmware versions earlier than July 2, 1995.

page 4 Computer Control of the Advantage SPM522D

Advanced Computer Control

The Advanced Computer Control command set includes commands which allow the
SPM522D to return information about the system to the computer, unlike Control Button
Emulation which is basically a one-way control mechanism. The following list
summarizes the commands available using Advanced Computer Control, including the
ASCII command character associated with each command:

!

virtual-button perform the specified button actions.

"

button-definition define or retrieve the definition for the specified button.

#

source-settings define or retrieve the stereo source settings (tone, balance).

$

preset-definition define or retrieve the definition for the specified preset.

%

do-misc miscellaneous functions.

&

do-button perform button actions for specified button.

'

do-preset-action perform the specified preset action.

(

do-volume-action perform the specified volume or balance action.

(

set-volume set the volume for the specified fader.

)

do-tone-action perform the specified bass or treble or balance action.

*

do-source-select perform the specified stereo source selection action.

+

sleep-for-10-sec. sleep for 10 seconds, ignoring all commands.

,

read-memory retrieve data from non-volatile configuration memory.

-

write-memory store data in non-volatile configuration memory.

.

set-factory-defaults resets configuration parameters to factory defaults.

/

get-version retrieve the model information and firmware version date.

Each Advanced Computer Control command requires at least two parameter bytes (four
pseudo-hex nibbles) to be sent prior to the command character. Each command will be
explained in detail on the following pages.

Some of the commands cause the SPM522D to return information to the computer. For
each string of information returned to the computer, the SPM522D terminates the string
by transmitting the ASCII carriage return character (0x0D - represented in this document
as  ). An internal dip-switch may be set to cause the SPM522D to append an ASCII line
feed character (0x0A) after each carriage return. This dip-switch is labelled "Opt. X".
When the Opt. X dip-switch is off, the option is disabled (no line feed); when the dip­switch is on, the option is enabled (a line feed follows each carriage return). The factory
default setting is Opx. X disabled (no line feed).

As mentioned earlier, the Advantage SPM522D will echo all characters it receives,
regardless of whether or not the characters are valid commands or parameters. Characters
greater than 0x7F are reserved and should not be transmitted by the computer. The
SPM522D utilizes a subset of the standard ASCII character set. The following characters
have meaning to the SPM522D:

Computer Control of the Advantage SPM522D page 5

character hexadecima

operation

l

ASCII control characters (0x00 - 0x1F) no operation

SPACE

ASCII

!

thru

0

thru

@
A
B

thru

a
b

thru

k

thru

{

thru

0x80 thru 0xFF (0x80 - 0xFF) RESERVED

character

/

?

`

j
z

DEL

(0x20) no operation

(0x21 - 0x2F) Advanced Computer Control

commands

(0x30 - 0x3F) pseudo-hex parameters for Advanced

Computer Control commands
(0x40) Control Button Emulation Repeat Code
(0x41) no operation

(0x42 - 0x60) Control Button Emulation commands

(buttons 01 - 31)
(0x61) no operation

(0x62 - 0x6A) Control Button Emulation commands

(buttons 32 - 40)

(0x6B - 0x7A) Control Button Emulation Device Select

Prefix commands

(0x7B - 0x7F) no operation

An ASCII code chart showing all SPM522D commands and codes is provided later in
this document for your convenience. One key point to observe is that the computer may
feel free to transmit spaces, tabs, carriage returns, line feeds, or any other control
characters at any time (even between two nibbles of a pseudo-hex parameter byte)
without having any affect on the operation of the SPM522D. The SPM522D will simply
echo them and then ignore them.

Device Type Bitmask and Device Number Bitmask

In a system which has more than one Advantage product connected to the computer, the
Device Type Bitmask and Device Number Bitmask command parameters provide a
mechanism for the computer to individually address a particular device (or a combination
of devices). Every command in the Advanced Computer Control command set requires
that a Device Type Bitmask and a Device Number Bitmask be transmitted as the last two
parameter bytes before the computer transmits the command character itself. These two
bitmask parameters bytes provide a device addressing capability to specify which of the
devices in the system should execute the command. All devices which are not
specifically addressed by these two bitmask values will ignore the command.

page 6 Computer Control of the Advantage SPM522D

The Device Type Bitmask parameter byte supports up to eight distinct device types - one
bit per device type. The eight device types are:

0x01 (bit 0) Biamp Advantage DRC 4+4 digital remote control
0x02 (bit 1) Biamp Advantage EQ28X digitally-controlled graphic equalizer
0x04 (bit 2) Biamp Advantage SPM522D stereo preamp/mixer
0x08 (bit 3) Biamp Advantage PMX84 programmable matrix switch
0x10 (bit 4) (reserved for future product)
0x20 (bit 5) (reserved for future product)
0x40 (bit 6) (reserved for future product)
0x80 (bit 7) (reserved for future product)

The Advantage SPM522D will only respond to Advanced Computer Control commands
if bit 2 of the Device Type Bitmask parameter byte is a '1'. A command may be directed
to more than one device type in the system by setting all of the corresponding bits in the
Device Type Bitmask to '1's.

The Device Number Bitmask parameter byte supports up to eight distinct device numbers

- one bit per device number. The eight device numbers are:

0x01 (bit 0) Select Device Number 1
0x02 (bit 1) Select Device Number 2
0x04 (bit 2) Select Device Number 3
0x08 (bit 3) Select Device Number 4
0x10 (bit 4) Select Device Number 5
0x20 (bit 5) Select Device Number 6
0x40 (bit 6) Select Device Number 7
0x80 (bit 7) Select Device Number 8

A particular Advantage SPM522D will only respond to Advanced Computer Control
commands if the bit in the Device Number Bitmask parameter byte corresponding to its
device number is a '1'. A command may be directed to more than one device number in
the system by setting all of the corresponding bits in the Device Number Bitmask to '1's.

The Advanced Computer Control command set supports, in theory, up to sixty-four
devices in a system - eight devices of each of the eight device types. In order for any
particular device in the system to respond to an Advanced Computer Control command,
the appropriate bit in both the Device Type and Device Number bitmask parameter bytes
must be set to '1'.

Computer Control of the Advantage SPM522D page 7

Preset Data Structure

The SPM522D firmware maintains data structures for 12 presets:

preset 0 Main power-up preset preset 6 Zone power-up preset
preset 1 Main preset 'A' preset 7 Zone preset 'E'
preset 2 Main preset 'B' preset 8 Zone preset 'F'
preset 3 Main preset 'C' preset 9 Zone preset 'G'
preset 4 Main preset 'D' preset 10 Zone preset 'H'
preset 5 Main "current mix" preset 11 Zone "current mix"

SPM522D Preset Data Structure

5-byte array with elements numbered preset[0] thru preset[4]

preset[4]

(transmitted first)

preset[3]

preset[2]]

preset[1]

preset[0]

(transmitted last)

(msb) (lsb)

Mute

Mic 2

Pri

Room
Comb

Mic 1

Pri

Ch5

OV

Mic 2

EN

LAST RECALLED

Mix

Mod

MIC 2 VOLUMEMute

MIC 1 VOLUMEMute

OUTPUT VOLUME

Mic 1

OV

EN

EN

PRESET

SELECTED

01234567

Note: This value is
only significant for presets
0 and 6 (power-up mixes)

SOURCE

Ch. 5 OVERRIDE ENABLED

MIC 1 ENABLED

MIC 2 ENABLED

MIC 1 PRIORITY

MIC 2 PRIORITY

The volume levels are 5-bit values which range from 0x00 (step 0 - minimum volume) to
0x1F (step 31 - maximum volume). Bit 7 of the volume bytes indicates whether or not
that particular fader is muted. If the fader is muted, the actual volume level sent to the
VCA is 0x00, but the volume level specified in the 5 least significant bits of the volume
byte indicates the volume level which will be restored when that fader becomes un­muted.

The fifth byte of the preset data structure (preset[4]) is used only for presets 0 and 6, the
power-up presets. The SPM522D periodically stores its current mix status in its non­volatile configuration memory as preset 0 (Main) and preset 6 (Zone). Unless configured
otherwise, the SPM522D will recall presets 0 and 6 upon power-up.

page 8 Computer Control of the Advantage SPM522D

Stereo Source Data Structure

The SPM522D maintains data structures for 6 stereo sources. Source 0 is not used.
Sources 1 thru 5 correspond to the five stereo inputs. These data structures contain the
Main treble, Main bass, Main balance, Zone treble, Zone bass, and Zone balance
information for each of the five stereo sources. Please note that the tone and balance
information is directly associated with each stereo source and not associated with presets.

SPM522D Stereo Source Data Structure

4-byte array with elements numbered source[0] thru source[3]

source[3]

(transmitted first)

source[2]

source[1]

source[0]

(transmitted last)

(msb) (lsb)

ZONE BALANCE VALUERL

ZONE BASS VALUEZONE TREBLE VALUE

RL

MAIN BALANCE VALUE

MAIN BASS VALUEMAIN TREBLE VALUE

01234567

Bass and Treble values range from 0x00 (maximum cut -12 dB) to 0x0C (maximum
boost +12 dB), with the value 0x06 corresponding to a "flat" response (no cut, no boost).

To best understand how the Balance control works, visualize two separate faders - one
which affects the volume level of the left channel and one which affects the right channel.
Each fader has a range of 0x08 (-24 dB) to 0x14 (0 dB). When the balance is centered,
both faders are set at their maximum values of 0x14. To shift the balance to the right,
decrease the left fader value. To shift the balance from the right back to the left, increase
the left fader value until it once again reaches maximum (0x14) and then continue to shift
to the left by decreasing the right fader value. At any given time, one or the other fader
will be at its maximum value (and they will both be at maximum when the balance is
centered). Since one value is always at maximum, there is no point in allocating space in
the data structure to store two fader values to represent one balance setting. Instead, only
one value is stored along with a flag bit to indicate whether the value is the left fader (bit

7) or the right fader value (bit 6). When the balance is centered, both fader values will be
maximum (0x14) and it doesn't matter whether you specify the left fader value or the
right fader value (the SPM522D will always report the value as if it is the left fader
value).

Computer Control of the Advantage SPM522D page 9

Button Definition Data Structure

The SPM522D maintains data structures for 41 buttons (button 0 thru button 40 - button
0 is not used). Each button definition data structure consists of eight bytes - four bytes for
Main button actions and four bytes for Zone button actions. The following illustration
indicates which bit fields of which bytes are used for each type of action.

SPM522D Button Data Structure

8-byte array with elements numbered button[0] thru button[7]

button[7]

(transmitted first)

button[6]

(msb) (lsb)

TREBLE

ACTION

MIC 2 VOL ACTION

BASS

ACTION

BALANCE ACTION

MIC 1 VOL ACTION

01234567

ZONE

button[5]

button[4]

button[3]

button[2]

OUTPUT VOL ACTION

TREBLE

ACTION

MIC 2 VOL ACTION

BASS

ACTION

SOURCE SELECT

ACTION

PRESET NUMBERPRESET ACTION

BALANCE ACTION

MIC 1 VOL ACTION

MAIN

button[1]

button[0]

(transmitted last)

OUTPUT VOL ACTION

SOURCE SELECT

ACTION

PRESET NUMBERPRESET ACTION

The bit patterns for the various button action codes are shown in the following tables:

Preset action codes:
0000 NOP (no operation)
0001 Recall Preset
0010 Store Preset
0011 Enter Combined Mode then Recall
0100 (reserved)
0101 Cancel Combined Mode then Recall
0110 (reserved)
0111 (reserved)
1000 Toggle Combined Mode then Recall

page 10 Computer Control of the Advantage SPM522D

Source Select action codes:
0000 NOP (no operation)
0001 select channel 1
0010 select channel 2
0011 select channel 3
0100 select channel 4
0101 select channel 5
0110 (reserved)
0111 toggle channel 5 Override
1000 channel 5 Override
1001 cancel channel 5 Override
1010 enable mic 1
1011 disable mic 1
1100 toggle mic 1 enable
1101 enable mic 2
1110 disable mic 2
1111 toggle mic 2 enable

Mic 1, Mic 2, and Output Volume action codes:
0000 NOP (no operation)
0001 volume down
0010 volume up
0011 toggle mute
0100 mute
0101 un-mute
0110 minimum volume
0111 maximum volume
1000 (reserved)
1001 set volume to predefined level

Balance action codes:
0000 NOP (no operation)
1101 shift to the Left
1110 shift to the Right
1111 set balance to center

Bass and Treble action codes:
0 0 NOP (no operation)
0 1 cut
1 0 boost
1 1 set to flat

Computer Control of the Advantage SPM522D page 11