Laird BTM430 User manual

BTM430/431 DATA MODULE
User Guide
Version 5.0
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1REVISION HISTORY
Revision
Date
Description
Approved By
1.0
3 Jan 2012
Initial Release
Jonathan Kaye
2.0
20 Mar 2012
Updates to firmware v11.28.1.0
Jonathan Kaye
3.0
11 May 2012
Formatting and general editing
Jonathan Kaye
4.0
7 Jan 2013
Updated FCC Statement, new mech. drawings, general
editing / formatting
Jonathan Kaye
4.1
15 Mar 2013
Converted to Laird formatting
Sue White
5.0
04 Feb 2014
Separated into two separate docs (Hardware
Integration Guide and User Guide). Added a Related
Documents section.
Sue White

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2TABLE OF CONTENTS
1Revision History....................................................................................................................................... 2
2Table of Contents.................................................................................................................................... 3
1. Overview and Key Features.................................................................................................................... 4
FEATURES AND BENEFITS ...................................................................................................................................4
2.1 APPLICATIONS ...............................................................................................................................................4
3AT Command Set Reference .................................................................................................................. 5
3.1 Introduction...................................................................................................................................................5
3.2 Assumptions ..................................................................................................................................................6
3.3 Commands.....................................................................................................................................................6
3.4 Unsolicited Responses .................................................................................................................................36
3.5 Incoming Connections .................................................................................................................................37
3.6 Dropping Connections .................................................................................................................................37
3.7 Pairing and Trusted Devices ........................................................................................................................38
3.8 Error Responses...........................................................................................................................................39
3.9 Factory Default Mode..................................................................................................................................40
3.10 Miscellaneous Features ...............................................................................................................................40
3.11 Known Issues ...............................................................................................................................................41
3.12 Disclaimers ..................................................................................................................................................42
3.13 Data Sheet Status ........................................................................................................................................42
3.14 Changes between release............................................................................................................................42
4PCM CODEC Interface...........................................................................................................................43
4.1 Compatible Codec Chips..............................................................................................................................43
5FTP Client Profile Commands ...............................................................................................................43
5.1 Generic Notes and Guidance.......................................................................................................................43
5.2 FTP related AT Commands ..........................................................................................................................44
5.2 FTP related Subcommands ..........................................................................................................................44
5.3 FTP related subresponses............................................................................................................................47
5.4 FTP line multiplexing commands.................................................................................................................49
5.5 Message Sequence Charts...........................................................................................................................50
6OBEX Profile Commands ......................................................................................................................64
6.1 Generic Notes and Guidance.......................................................................................................................65
6.2 OBEX Push related AT Commands...............................................................................................................65
6.2 OBEX Push related Subcommands ..............................................................................................................65
6.3 OBEX Push Related Subresponses ...............................................................................................................66
6.4 OBEX Push Line Multiplexing Commands....................................................................................................68
6.5 Message Sequence Charts...........................................................................................................................69
7Related Documents............................................................................................................................... 73

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1. OVERVIEW AND KEY FEATURES
The BTM430 and BTM431 Bluetooth®modules from Laird Technologies have been designed to meet the
needs of developers who wish to add robust, short range Bluetooth data connectivity to their products. They
are based on the market leading Cambridge Silicon Radio BC04 chipset, providing exceptionally low power
consumption with outstanding range.
With physical sizes as small as 12.5 x 18.0mm and best of class, low-power operation, these modules are the
ideal choice for applications where designers need both performance and minimum size. For maximum
flexibility in systems integration, the modules are designed to support a separate power supply for I/O.
To aid product development and integration, Laird Technologies has integrated a complete Bluetooth
protocol stack within the modules, including support for the Bluetooth Serial Port Profile. The modules are
fully qualified as Bluetooth End Products, allowing designers to integrate them within their own products
with no further Bluetooth Qualification. They can then list and promote their products on the Bluetooth
website free of charge.
A comprehensive AT command interface is included, which simplifies firmware integration. Combined with a
low cost developer’s kit, this ensures that the choice of Laird Technologies Bluetooth modules guarantees the
fastest route to market.
FEATURES AND BENEFITS
Bluetooth®v2.0+EDR
Adaptive Frequency Hopping to cope with
interference from other wireless devices
External or internal antenna options
Comprehensive AT interface
for simple programming
Bluetooth®END Product Qualified
Compact size
Class 2 output –4dBm
Low power operation
UART interface
PCM and SCO for external codec
GPIO lines under AT control
Support for multiple profiles
Wi-Fi co-existence
2.1 APPLICATIONS
Embedded Devices
Phone Accessories
Security Devices
Medical and Wellness Devices
Automotive Applications
Bluetooth Advertising
ePOS

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3AT COMMAND SET REFERENCE
3.1 Introduction
This document describes the protocol used to control and configure the following Laird Technologies
Bluetooth devices:
BTM430
BTM431
The protocol is similar to the industry standard Hayes AT protocol used in telephony modems which is
appropriate for cable replacement scenarios, as both types of devices are connection oriented. The telephony
commands have been extended to make the Laird Technologies device perform the two core actions of a
Bluetooth device, which is make/break a connection and Inquiry. Other AT commands are also provided to
perform ancillary functions, such as, pairing, trusted device database management and S Register
maintenance.
Just like telephony modems, the Laird Technologies device powers up in an unconnected state and will only
respond via the serial interface. In this state the Laird Technologies device will not even respond to Bluetooth
Inquiries. Then, just like controlling a modem, the host can issue AT commands which map to various
Bluetooth activities. The command set is extensive enough to allow a host to make connections which are
authenticated and/or encrypted or not authenticated and/or encrypted or any combination of these.
Commands can be saved, so that on a subsequent power up the device is discoverable or automatically
connects.
The device has a serial interface which can be configured for baud rates from 1200 up to 921600, and an RF
communications end point. The latter has a concept of connected and unconnected modes and the former
will have a concept of command and data modes. This leads to the matrix of states shown below.
Table 1: Matrix of mode states
RF Unconnected
RF Connected
Local Command Mode
OK
OK
Remote Command Mode
ILLEGAL
OK
Data Mode
ILLEGAL
OK
The combinations ‘Data and RF Unconnected Mode’ and ‘Remote Command and RF Unconnected Mode’ do
not make sense and will be ignored.
Navigation between these states is done using the AT commands which are described in detail in subsequent
sections.

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3.2 Assumptions
The CSR (Cambridge Silicon Radio) BC04 chipset in Laird Technologies devices is memory resource limited.
Therefore it is NOT proposed that there be full implementation of the AT protocol as seen in modems. The
claim made for this device is that it will have a protocol similar to an AT modem. In fact, the protocol is
similar enough so that existing source code written for modems can be used with very little modification with
a Laird Technologies device.
Therefore the following assumptions are made:
All commands are terminated by the carriage return character 0x0D, which is represented by the string
<cr> in descriptions below this cannot be changed.
All responses from the Laird Technologies device have carriage return and linefeed characters
preceding and appending the response. These dual character sequences have the values 0x0D and
0x0A respectively and shall be represented by the string <cr,lf>.
All Bluetooth addresses are represented by a fixed 12 digit hexadecimal string, case insensitive.
All Bluetooth Device Class codes are represented by a fixed 6 digit hexadecimal string, case insensitive.
All new Bluetooth specific commands are identified by the string +BTx, where xis generally a
mnemonic of the intended functionality.
3.3 Commands
This section describes all available AT commands. Many commands require mandatory parameters and some
take optional parameters. These parameters are integer values, strings, Bluetooth addresses, or device classes.
The following convention is used when describing the various AT commands.
<bd_addr>
A 12 character Bluetooth address consisting of ASCII characters ‘0’ to ‘9’, ‘A’
to ‘F’ and ‘a’ to ‘f’.
<devclass>
A 6 character Bluetooth device class consisting of ASCII characters ‘0’ to ‘9’,
‘A’ to ‘F’ and ‘a’ to ‘f’.
n
A positive integer value.
m
An integer value (positive or negative) which can be entered as a decimal
value or in hexadecimal if preceded by the ‘$’ character. E.g. the value 1234
can also be entered as $4D2
<string>
A string delimited by double quotes. E.g. "Hello World". The " character
MUST be supplied as delimiters.
<uuid>
A 4 character UUID number consisting of ASCII characters ‘0’ to ‘9’, ‘A’ to ‘F’
and ‘a’ to ‘f’.

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1. ^^^ {Enter Local Command Mode}
When in data and connected mode, the host can force the device into a command and connected mode so
that AT Commands can be issued to the device. The character in this escape sequence is specified in the S2
register, so can be changed. In addition, the escape sequence guard time is specified by S Register 12. By
default the guard time is set to 100 milliseconds. Please refer to Section 5: Dropping Connections for more
related information.
In modems this escape sequence is usually “+++”. “^^^” is specified to avoid confusion when the module is
providing access to a modem.
Response: <cr,lf>OK<cr,lf>
2. !!! {Enter Remote Command Mode}
When in data and connected mode, the host can force the remote device into a command and connected
mode so that AT Commands can be issued to the device remotely. The escape sequence guard time is
specified by S Register 12 and is the same as per the ^^^ escape sequence. By default the guard time is set
to 100 milliseconds. The remote device issues ATO as normal to return to data mode. (Refer to 2.2.12)
For this command to be effective S Register 536 must be set to 1.
Response: <cr,lf>OK<cr,lf>
3. AT
Used to check the module is available.
Response: <cr,lf>OK<cr,lf>
4. ATA {Answer Call}
Accept an incoming connection, which is indicated by the unsolicited string
<cr,lf>RING 123456789012<cr,lf> every second. 123456789012 is the Bluetooth address of the connecting
device.
Response: <cr,lf>CONNECT 123456789012<cr,lf>
5. ATD<U><Y><bd_addr>,<uuid> {Make Outgoing Connection}
Make a connection to device with Bluetooth address <bd_addr> and profile <uuid>. The <uuid> is an
optional parameter which specifies the UUID of the profile server to attach to, and if not supplied then the
default UUID from S Register 101 is used. As this is a Laird Technologies device which utilises the RFCOMM
layer as described in the Bluetooth specification, it necessarily implies that only profiles based on RFCOMM
can be accessed.
If <U> is not specified, then authentication is as per register 500, otherwise the connection will be
authenticated.
If <Y> is not specified, then encryption is as per register 501, otherwise the connection will have encryption
enabled.
The timeout is specified by S register 505.
Response: <cr,lf>CONNECT 123456789012<cr,lf>
Or <cr,lf>NO CARRIER<cr,lf>

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Due to a known issue in the Bluetooth RFCOMM stack, it is not possible to make more than 65525 outgoing
connections. Therefore if that number is exceeded, then the connection attempt will fail with the following
response:
Response: <cr,lf>CALL LIMIT
Or <cr,lf>NO CARRIER<cr,lf>
In that case, issuing an ATZ to reset the device will reset the count to 0 and more connections are possible.
The following RFCOMM based UUIDs are defined in the Bluetooth Specification:
Profile Name
UUID
Serial Port
1101
LAN Access Using PPP
1102
Dialup Networking
1103
IrMC Sync
1104
OBEX Object Push
1105
OBEX File Transfer
1106
IrMC Sync Command
1107
Headset
1108
Cordless Telephony
1109
Intercom
1110
Fax
1111
Audio Gateway
1112
WAP
1113
WAP_CLIENT
1114
6. ATD<U><Y><bd_addr>,<ServiceName> {Make Connection}
Make a connection to device with Bluetooth address <bd_addr> and profile specified via S Reg 101 AND
which has a service name starting with the string <ServiceName>. The ServiceName parameter is a string
delimited by “.
If <U> is not specified, then authentication is as per register 500, otherwise the connection will be
authenticated.
If <Y> is not specified, then encryption is as per register 501, otherwise the connection will have encryption
enabled.
The timeout is specified by S register 505.
Response: <cr,lf>CONNECT 123456789012<cr,lf>
Or <cr,lf>NO CARRIER<cr,lf>
7. ATD<U><Y>L {Remake Connection}
Make a connection with the same device and service as that specified in the most recent ATD command. The
<UY> modifiers are optional. An error will be returned if the ‘L’ modifier is specified AND a Bluetooth
address.

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If both ‘L’ and ‘R’ modifiers are specified then an error will be returned.
Response: <cr,lf>CONNECT 123456789012 AE<cr,lf>
Or <cr,lf>NO CARRIER<cr,lf>
8. ATD<U><Y>R {Make Connection to peer specified in AT+BTR}
Make a connection with the device address specified in the most recent AT+BTR command. The service is as
specified in S Register 101. The <UY> modifiers are optional. An error will be returned if the ‘R’ modifier is
specified AND a Bluetooth address.
If both ‘R’ and ‘L’ modifiers are specified then an error will be returned.
Response: <cr,lf>CONNECT 123456789012 AE<cr,lf>
Or <cr,lf>NO CARRIER<cr,lf>
9. ATEn {Enable/Disable Echo}
This command enables or disables the echo of characters to the screen. A valid parameter value will be
written to S Register 506.
E0
Disable echo.
E1
Enable echo.
All other values of n will generate an error.
Response: <cr,lf>OK<cr,lf>
Or <cr,lf>ERROR nn<cr,lf>
10. ATH {Drop Connection}
Drop an existing connection or reject an incoming connection indicated by unsolicited RING messages.
Response: <cr,lf>NO CARRIER<cr,lf>
11. ATIn {Information}
This will return the following information about the Laird Technologies device.
I0
The product name/variant.
I1
The CSR firmware build number.
I2
The Laird Technologies firmware build number. For internal use only.
I3
The Laird Technologies firmware revision.
I4
A 12 digit hexadecimal number corresponding to the Bluetooth address of the Laird
Technologies device.
I5
The manufacturer of this device.
I6
The maximum size of trusted device database.
I7
The manufacturer of the Bluetooth chipset.
I8
The chipset format.
I9
0 if not in a connect state and 1 if in a connect state.

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I11
The reason why a “NO CARRIER” resulted in the most recent attempt at making an outgoing
connection. Where the response values are as follows:
0 = No prior connection
1 = Connection timeout
2 = Connection attempt cancelled
3 = Normal disconnection
4 = Peer device has refused connection
5 = Service profile <uuid> requested not available on remote device
6 = Connection has failed
32 = ATH was entered
33 = Incoming connection aborted because too many rings
34 = Unexpected incoming connection
35 = Invalid address
36 = DSR is not asserted
37 = Call limit of 65531 connections has been reached
38 = Pairing in progress
39 = No link key
40 = Invalid link key
255 = Unknown Reason
I12
The last ERROR response number.
I13
The Sniff status is returned as follows:-
Response: <cr,lf>a:b,c,d,e<cr,lf>OK<cr,lf>
Where ‘a’ = 0 when not online and 1 when online and Sniff has been enabled, ‘b’ is the Sniff
Attempt parameter, ‘c’ is the Sniff timeout parameter, ‘d’ is the minimum sniff interval and ‘e’
is the maximum sniff interval. All parameters ‘b’, ’c’, ’d’ and ‘e’ are given as Bluetooth slots
which are 625 microseconds long converted from values of S Registers 561, 562, 563 and
564 respectively.
I14
The current boot mode (Only for firmware 1.18.0 and newer)
I15
The maximum length of an AT command, including the terminating carriage return (only for
firmware 1.6.10 and newer)
I16
The size of AT command input buffer
I20
Returns the number of bytes pending to be sent in the RF buffer when a connection is up.
I33
Version number of Multipoint application
Note: ATI is provided for compatibility in multipoint mode; other AT commands are not
available.
I42
State information. Where the response values are as follows:
13 = NotOpen
14 = OpenIdle
15 = Ringing
16 = OnlineCommand
172 to 177 = waiting for connectable and/or discoverable where the lowest significant digit
equates to the value stored in S Register 512 or 555.
Note: When n=16, ATI9 will return 1.

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I101
The RSSI value in dBm. If a connection does NOT exist then a value of -32786 is returned.
A value of 0 means the RSSI is within the golden range this is quite a large band, therefore
RSSI is not always a useful indicator. Use ATI111 instead which returns the bit error rate.
I111
Returns LinkQual which in the CSR chipset is defined as BER (bit error rate). This returns a
value which is the number of bits in error out of 1 million. Hence a value of 0 is best, and
larger values are worse. As the value approaches 1000 (BER = 0.1%) it is an indication that
the link is very bad and a large number of Bluetooth packets are being lost.
I333
Returns extended firmware version number.
For recognised values of n. All other values of n will generate an error.
Response: <cr,lf>As Appropriate<cr,lf>OK<cr,lf>
Or <cr,lf>ERROR nn<cr,lf>
12. ATO {Enter Data Mode} (letter ‘o’)
Return to data mode. Assume that the module is in data mode after OK is received. Responds with an error if
there is no Bluetooth connection.
Response: <cr,lf> CONNECT 123456789012<cr,lf>
Or <cr,lf>ERROR nn<cr,lf>
13. ATSn=m {Set S Register}
As with modems, the Laird Technologies Bluetooth module employs a concept of registers which are used to
store parameters (such as escape sequence character and inquiry delay time) as listed in detail below.
The value part ‘m’ can be entered as decimal or hexadecimal. A hexadecimal value is specified via a ‘$’
leading character. For example $1234 is a hexadecimal number.
When S register values are changed, the changes are not stored in non-volatile memory UNTIL the AT&W
command is used. Note that AT&W does not affect S registers 520 to 525 or 1000 to 1010 as they are
updated in non-volatile memory when the command is received.
Table 2: S Registers
Register
Default
Range
Comment
S0
1
-1..15
Number of RING indication before automatically answering an
incoming connection. A value of 0 disables autoanswer. If -1, then
autoanswer on one RING and do NOT send RING/CONNECT
response to the host. This emulates a serial cable replacement
situation.
Setting values >= 0 resets S504 to 0 and <0 forces 504 to 1.
If S0 <> 0 and S100 <> 0 then S0 must be < S100. If a value is
entered which violates this rule, then ERROR 29 is sent in response.
If S504 =1 then this register will return -1, regardless of the actual
value stored in non-volatile memory.
S2
0x5E
0x20..0x7E
Escape sequence character. It is not ‘+’ by default as a Bluetooth
serial link can be used to connect to a mobile phone which
exposes an AT command set, which will in turn use ‘+’ as default.
So if both used ‘+’ there will be confusion. 0x5e is the character
‘^’.

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Register
Default
Range
Comment
S12
100
40..5000
Escape sequence guard time in milliseconds, with a granularity of
20ms. New values are rounded down to the nearest 20ms
multiple.
S100
15
0..15
Number of RING indications before an auto disconnection is
initiated. A value of 0 disables this feature.
If S0 <> 0 and S100 <> 0 then S0 must be < S100. If a value is
entered which violates this rule, then ERROR 29 is sent in response.
S101
$1101
0..$ffff
UUID of default SPP based profile when not specified explicitly in
the ATD command.
S102
1
1..$7F
Defines a set of bits masks for enabling profile servers. Values can
be ORed.
1 is Serial Port Profile
2 is Headset ( S Reg 580 allows remote volume control bit to be
adjusted)
4 is DUN
8 is Audio Gateway (Headset)
16 is Handsfree (S Reg 581 allows supported feature field to be
adjusted)
32 is OBEX FTP
64 is Audio Gateway (Handsfree)
It is recommended that due to memory resource issues, not more
than 2 profiles are activated at the same time.
S103
1
1..7
Boot Mode on cold boot.
S126
?
0 .. 0xFFFF
Primer for changing to Multipoint mode
S127
?
0 .. 0xFFFF
0x100 for At mode
0x200 for Multipoint mode
Other values are reserved
S400
0
0..1
Pio deamon.
1 = Hostless Audio gateway Operation
S401
1000
100..5000
In Hostless Audio Gateway Operation –GPIO4 flash period while
inquiring
S402
0
0..100
In Hostless Audio Gateway Operation –GPIO4 flash duty cycle
while inquiring
S403
1000
100..5000
In Hostless Audio Gateway Operation –GPIO4 flash period when
there is an ACL connection only to the headset
S404
0
0..100
In Hostless Audio Gateway Operation –GPIO4 flash duty cycle
when there is an ACL connection only to the headset
S405
1000
100..5000
In Hostless Audio Gateway Operation –GPIO4 flash period when
there is an ACL and SCO connection to the headset
S406
0
0..100
In Hostless Audio Gateway Operation –GPIO4 flash duty cycle
when there is an ACL and SCO connection to the headset
S407
0
0..1
In Hostless Audio Gateway Operation –‘Lift-Hook’ output follows
SCO state

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Register
Default
Range
Comment
S408
0
0..1
In Hostless Audio Gateway Operation –if set to 1 then delete
trusted device database when inquiry is initiated to look for
headsets
S409
0
0..1
In Hostless Audio Gateway Operation –when inquiring and
pairing, use the device class code of the response to classify which
uuid to connect to the headset when initiating a Bluetooth
connection from the gateway
S410
0
0..1
In AudioGateway Hostless mode, if set to 1, AG”” async responses
will be forced out from the UART –good for debugging
S411
500
4000
In AudioGateway Hostless mode, Short press duration in
milliseconds. 500msec granularity
S412
500
4000
In AudioGateway Hostless mode, component of medium press
duration in milliseconds. 500msec granularity. Actual duration is
this value plus S411
S413
500
4000
In AudioGateway Hostless mode, component of long press
duration in milliseconds. 500msec granularity. Actual duration is
this value plus S412 plus S411
S414
30
240
In AudioGateway Hostless mode, The inquiry to search for
headsets will be aborted after this amount of time, in seconds. The
granularity is 30 seconds.
S420
0
1
If this is set, then the module maintains a seconds counter. Use
ATI420 to read the count value. It is basically the time the module
has been powered up in seconds.
S500
0
0..1
Authentication for outgoing connections. Set to 1 to Enable
Authentication.
S501
0
0..1
Encryption for outgoing connections. Set to 1 to Enable
Encryption.
S502
0
0..1
Authentication for incoming connections. Set to 1 to Enable
Authentication.
S503
0
0..1
Encryption for incoming connections. Set to 1 to Enable
Encryption.
S504
0
0..1
Setting to 1 will force S0 to -1 and will suppress messages arising
from connections or pairing. E.g. CONNECT, NO CARRIER, RING,
PAIR etc.
Suppressing connection based messaged allows the Laird
Technologies device to be configured in cable replacement mode.
S505
10
2..120
Minimum delay before abandoning connection attempt as a
master. Referenced by ATD. In units of seconds. See S Registers
530 and 543 also.
Please note that as disconnection time can vary; this register only
guarantees the minimum delay. Note that for invalid addresses
specified in the ATD command, the “NO CARRIER” response will
be immediate. See S register 560 for specifying disconnect max
timeout.
S506
1
0..1
Enable/Disable echoes. The ATEn command also affects this.

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Register
Default
Range
Comment
S507
0
0..2
When set to 0, a connection can be dropped using ^^^ escape
sequence only and the state of DSR line is ignored.
When set to 1 a connection can be dropped using EITHER the ^^^
escape sequence OR the DSR handshaking line. When set to 2, a
connection can only dropped using a deassertion of DSR. Mode 2
provides for the highest data transfer rate.
If the status of the DSR line is to be conveyed to the remote device
as a low bandwidth signal then this register MUST be set to 0,
otherwise a deassertion of DSR will be seen as a request to drop
the Bluetooth connection.
This register affects S Register 536 –see details of 536
For the Go blue Activator variant this can only be set to 0.
S508
640
10..2550
Page Scan Interval in milliseconds. Minimum is 11.25ms so
10/11ms will give 11.25ms.
S509
320
10..2550
Page Scan Window in milliseconds. Minimum is 11.25ms so
10/11ms will give 11.25ms.
S510
640
10..2550
Inquiry Scan Interval in milliseconds. Minimum is 11.25ms so
10/11ms will give 11.25ms.
S511
320
10..2550
Inquiry Scan Window in milliseconds. Minimum is 11.25ms so
10/11ms will give 11.25ms.
S512
1
0..7
Specify power up state.
When set to 0, AT+BTO is required to open the device for
Bluetooth activity.
When set to 1, it proceeds to a state as if AT+BTO was entered.
When set to 2, it will be discoverable only, similar to issuing
AT+BTQ.
When set to 3, it will be connectable but not discoverable e.g.
AT+BTG
When set to 4, it will be connectable and discoverable e.g.
AT+BTP.
When set to 5, it will be like 2, but all UART RX traffic is discarded
in absence of a connection while DSR is asserted. If DSR is not
asserted, then it behaves exactly as per mode 2.
When set to 6, it will be like 3, but all UART RX traffic is discarded
in absence of a connection while DSR is asserted. If DSR is not
asserted, then it behaves exactly as per mode 3.
When set to 7, it will be like 4, but all UART RX traffic is discarded
in absence of a connection while DSR is asserted. If DSR is not
asserted, then it behaves exactly as per mode 4.
Note: By implication, a change to this can only be seen after a
power cycle AND if AT&W is actioned prior to the power cycle.
If S Reg 554 is non-zero and this register is between 2 and 7
inclusive, then the value of S554 specifies the time in seconds that
the device will remain in the specified mode after power up. On
timeout, the device will fall back to the mode specified in S
Register 555.

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Register
Default
Range
Comment
In modes 5, 6, 7 when all RX activity is ignored, only the special
command (capitalised) AT+BT&BISM& terminated by a <cr> will
force the module temporarily back into modes 2, 3 and 4
respectively.
In some firmware builds, S Registers 565 to 569 inclusive are
visible, which allows the start-up mode to depend on the state of
RI line (Setting S Reg 565 forces the RI pin to be configured as an
input). For this feature to be active, SReg 565 should be set to 1. In
that case, on start-up, if RI is asserted, then the start-up mode is
defined by S Reg 566 and if deasserted then S Reg 567.
S513
1
0..1
Pairing Authentication, 1 = Enable
S514
10
1..60
Pairing Timeout in seconds. This includes the time a host takes to
supply the PIN number when PIN? messages are indicated.
S515
0x001F00
0.. 0xFFFFFF
Default Device Class Code to be used with AT+BTO when it is not
explicitly specified. When queried, the value is always printed as a
hexadecimal number.
To change the device class of the module, after AT+BTO, use the
command AT+BTC.
S516
0x000000
0..0x2FFFFFF
Default Device Class filter to be used with AT+BTI when it is not
explicitly specified. When queried the value is always printed as a
hex number.
The seventh most significant digit, can be 0, 1 or 2, and is used to
specify the type of device class filter.
When 0, it specifies no filtering.
When 1, it specifies an AND mask and all 24 bits are relevant
When 2, it specifies a filter to look for devices with matching major
device class which occupies a 5 bit field from bits 8 to 12 inclusive
(assuming numbering starts at bit 0). All other 19 bits MUST be set
to 0.
S517
20
2..61
Inquiry Length in units of seconds. This parameter is referenced by
the AT+BTI command
S518
8
0..255
Maximum number of responses from an inquiry request. This
parameter is reference by the AT+BTI command. If this number is
set too high, then AT+BTI will return ERROR 27. For a particular
firmware revision, determine the effective maximum value by trial
and error. That is, set to a high value, send AT+BTI and if ERROR
27 is returned, then retry with a smaller value. This effective max
value will remain unchanged for that particular firmware build.
S519
500
100..6000
When S507>0, and in a connection, DSR can be used to change
from data to command state by deasserting the DSR line for less
than the time specified in this register. This value is rounded down
to the nearest 100ms

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Register
Default
Range
Comment
S520
Depends
on device
–see
comments
1200..11520
0
Change to a standard baud rate. The effect is immediate and in
fact the OK will be sent at the new baud rate. Only one of the
following baud rates are accepted:
1200,2400,4800,9600,19200,28800,38400,57600,115200.
If S register 525=1, then the maximum baud rate is limited to
115200
The default is 9600 for Laird Technologies’ BTM430 / BTM431.
For the Go blue Activator variant of the module this register is read
only
See S Register 526 for further information.
S521
See
Comment
1200..
921600
Change baud rate to non-standard value. Laird Technologies’
modules support any baud rate. The only limitation is the integer
arithmetic involved, which may adjust the applied rate slightly. If
the internally computed baud rate is more than 2% offset from
the desired input value, then an ERROR will be returned and the
old baud rate will prevail. To inspect the actual baud rate, do
ATS521?
S521 should only be sued for non-standard baud rates. For
standard baud rates use S520.
The effect is immediate and in fact the OK will be sent at the new
baud rate.
If S Register 525=1, then the max baud rate is limited to 115200
In the event that a non-standard baud rate is requested, it is
entirely possible that the host is not capable of generating such a
baud rate. In this case the Laird Technologies device cannot be
communicated with. If this happens, there is a procedure to
recover from this situation which is described in section titled
“Factory Default Mode”
The default is 9600 for the Laird Technologies Module and 115200
for other Laird Technologies devices.
For the Go blue Activator variant of the module this register is read
only
See S Register 526 for further information
S522
1
1
1 = CTS/RTS hardware handshaking enabled
For the Go blue Activator variant of the module this register is read
only.
See S Register 526 for further information.
S523
1
1..2
Number of Stop bits
For the Go blue Activator variant of the module this register is read
only.
See S Register 526 for further information.
S524
0
0..2
Parity. 0=None, 1=Odd, 2=Even
For the Go blue Activator variant of the module this register is read
only.
See S Register 526 for further information.

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Register
Default
Range
Comment
S525
See
Comment
0..1
Apply multiplier of 8 to baud rate internally. This is set to 0
(disabled) by default for the Laird Technologies Module/RS-232
Adaptor/Universal RS-232 Adaptor, and set to 1 (enabled) by
default for the Laird Technologies PC Card.
It is required in the PC Card because the UART chip on the PC
Card is driven by a 14.7456MHZ crystal instead of 1.8432MHz.
This means that when a host asks for a baud rate, in reality it gets
a baud rate which is 8 times faster.
If S Register 521 > 115200 then this register cannot be set to 1.
For the Go blue Activator variant of the module this register is read
only.
See S Register 526 for further information.
S526
3
1..3
This register specifies a 2 bit mask used to qualify how S Registers
520 to 525 are actioned.
When bit 0 is 1, the new comms parameter affects the UART
immediately.
When bit 1 is 1, the new comms parameter is stored in non-
volatile memory.
For example, to change comms parameters, but have them come
into effect only after subsequent power cycles, then this register
should be set to 2, and likewise to affect immediately and yet not
have it persist over a power cycle, the value should be set to 1.
Must be set before the baud rate change.
S530
1000
100..15000
Reconnect delay when configured as master in pure-cable-
replacement mode. This value is rounded down to the nearest
100ms. See S Register 505 and 543 also
S531
0
0..5
Specifies the mode on connection establishment.
0 = Normal, that data is exchanged between UART and RF
1 = LOCAL_COMMAND. UART input is parsed by the AT
interpreter and RF data is discarded
2 = REMOTE_COMMAND. RF input is parsed by the AT interpreter
and UART data is discarded. If S Reg 536 is not 1 then this register
cannot be set to 2 and an ERROR will be returned
3=LOCAL_COMMAND. UART input is parsed by the AT interpreter
and incoming RF data is sent to the host using the RX<string>
asynchronous response.
4=LOCAL_COMMAND and on the RF side, the GPIO is
automatically sent when there is a change in input. See section 9.5
for more details.
5=DEAMON mode
S532
0
0..7
If non zero, then on every connection, a SCO channel (audio) will
be initiated. Bit 0 for HV1, Bit1 for HV2 and Bit2 for HV3. When
the connection is lost, the SCO channel disappears along with it.

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Register
Default
Range
Comment
S533
1
0..2
If set to 1, then GPIO5 follows RI state, if set to 2 then it follows
the state of DSR and if 0 it is not driven and GPIO5 is available as a
user I/O.
This register will not necessarily be effective immediately after
changing the value. It must be saved to non-volatile memory using
AT&W and will operate as expected after an ATZ or a power cycle.
S534
1
0..2
When set to 0, GPIO4 is available as user i/o
If set to 1 then right LED follows DCD state. If set to 2 then the led
behaves as per setting 1, but in addition, when not in a
connection, if the device is connectable or discoverable, then the
led will blink.
This register will not necessarily be effective immediately after
changing the value. It must be saved to non-volatile store using
AT&W and will operate as expected after an ATZ or a power cycle.
S535
20
0..41
Link Supervision Timeout. If units go out of range, then a NO
CARRIER message will be sent to the host after the time specified
here
S536
0
0..1
When set to 1, a remote device can ‘capture’ the AT parser of this
unit by it sending this module an escape “!!!” sequence. The inter
character timing is set via S Register 12.
If S Register 507 is >= 2, then reading this register will always
return 0 and writing 1 will result in ERROR 33.
S537
X
X..X
This register is no longer available –see 551,552,553 instead
It only exists in firmware version 1.1.12 to 1.1.47
The functionality it controlled is now defined by registers 551,552
and 553
S538
0
0..1
If 1, then when a successful pairing occurs, it is automatically saved
in the trusted device database –if it has room to store it.
S539
0
0..1
When set to 1, in idle mode (S512=1), UART Rx characters are
discarded if DSR is deasserted.
S540
0
0 48..127
Sets the MTU in L2CAP configuration negotiations. The value of 0
is a special value which is taken to mean that the current value
should remain.
S541
6
-50..6
This sets the power level in dBm when inquiring or paging.
Reading this register returns the value stored in non-volatile
memory.
S542
6
-50..6
As per S541, however reading this register returns the current
power level as set in the base band. The read can be different from
S541because the actual power is set using a lookup table and the
base band rounds down to the nearest value in the table.

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Register
Default
Range
Comment
S543
0
0..1
If this is set to 1, then incoming pairing attempts will be accepted
(if a pin code has been pre-entered using AT+BTK) while in the
wait phase of auto connect cycle initiated by the AT+BTR
command. In addition to accepting pairing attempts, if the pairing
is successful, then the new device is automatically set as the peer
address for automatic connections (as if an explicit AT+BTR
command was entered).
See S Register 505 and 530 also
S544
1
0..1
Configure the UART for either low latency or maximum
throughput. A setting of 1 gives maximum throughput.
S551
0x3211
0xFFFF
This register specifies in each 4 bit nibble, how the outgoing
modem status bits to the remote peer gets its value. Bluetooth
allows for RTR, RTC, DV and IC bits to be exchanged over an
RFCOMM connection.
Nibble 0..3 specifies the source for RTC
4..7 specifies the source for RTR
8..11 specifies the source for DV (i.e. DCD)
12..15 specifies the source for IC (i.e. RI)
Each nibble can take the following value:-
0 Always set to 0
1 Always set to 1
2 If DCD (pin 8 on module connector) is output then always 1
If DCD is input then 1 if DCD is asserted otherwise 0
3 If RI (pin 6) is output then always 0
If RI is input then 1 if RI is asserted otherwise 0
If DSR (pin 10) is asserted then 1 otherwise 0
In the event that a nibble specifies DSR as the source of its state,
be aware that if, S Register 507 is anything other than 0, a de-
assertion of DSR will cause the Bluetooth connection to be
dropped.
If bits 0..3 and 4..7 are set to 0, then some Bluetooth devices will
use that as a signal to stop sending any data back. For example,
Nokia 6310 stops responding.
If this register is changed while in command and connected mode,
then on going back online using the ATO command, a fresh signal
will be sent to the peer to update the bits.

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Register
Default
Range
Comment
S552
0x0122
0x0FFF
This register specifies in each 4 bit nibble, how the DTR, DCD, RI
output pins are controlled when in a Bluetooth connection
Nibble 0..3 specifies the source for DTR
4..7 specifies the source for DCD
8..11 specifies the source for RI
Each nibble can take the following value:-
0 Do NOT touch the I/O
1 Always deassert
2 Always assert
3 If RTC bit in CONTROL_IND is 1 then assert otherwise deassert
4 If RTR bit in CONTROL_IND is 1 then assert otherwise deassert
5 If DV bit in CONTROL_IND is 1 then assert otherwise deassert
6 If IC bit in CONTROL_IND is 1 then assert otherwise deassert
If this register is changed while in command and connected mode,
then on going back online using the ATO command, the modem
output lines will get refreshed.
S553
0x0201
0x0FFF
This register specifies in each 4 bit nibble, how the DTR,DCD,RI
output pins are controlled when NOT in a Bluetooth connection
Nibble 0..3 specifies the source for DTR
4..7 specifies the source for DCD
8..11 specifies the source for RI
In addition it also refers to S Register 552 to see if the relevant pin
is an input or not to be touched. If the nibble in 552 is 0, then the
relevant pin is an input.
Each nibble can take the following value:-
0 Always deassert
1 Always assert
2 Assert if RING is being sent to the host
The default for the Universal RS-232 Adaptor is $0200.
S554
0
0..900
If S Register 512>=2 and <=7 then this register specifies a time in
seconds for which the device will stay in the S512 mode after
power up or reset. On timeout, it will abort the discoverable and/or
connectable and fall back into S512=1 mode, when it is deaf and
dumb.
Note that if AT+BTR has been used to specify a peer device, then
on reverting to mode 1, it will attempt to make a connection to
that peer device.
A power cycle, reset via BREAK or ATZ is required to see the effects
of change.