Laird BTM430 User manual

BTM430/431
DATA MODULE
USER MANUAL
Innovative Technology
for a Connected World
www.lairdtech.com
This datasheet has been downloaded fromhttp://www.digchip.com at this page

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
REVISION HISTORY
Revision Description
REVISION
HISTORY

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
CONTENTS
BTM430/431 Bluetooth®Module ..4
Overview .............................................. 4
BTM430/431 Key Features ................... 4
Specications ................................5
Detailed Specications ......................... 5
Pin Denitions ...................................... 7
Operating Parameters ...................8
Voltage Specications .......................... 8
AT Command Set Reference ..........9
Introduction ......................................... 9
Module Conguration Commands .... 10
Connection Management
Commands ........................................ 25
Audio Link Management
Commands ........................................ 35
SPP Prole Commands........................ 36
FTP Client Prole Commands.............. 37
OBEX Prole Commands .................... 53
Unsolicited Responses ........................ 61
Error Responses................................... 62
FCC Regulatory Statements .........63
BTM430 FCC and Industry
Canada Statements ............................ 63
BTM431 FCC and Industry
Canada Statements ............................ 63
Declarations of Compliance ........64
BTM430 EU Declaration
of Conformity .................................... 64
BTM431 EU Declaration
of Conformity .................................... 65
Mechanical Drawings ..................66
BTM430 Mechanical Details ............... 66
BTM431 Mechanical Details ............... 68
Development Kit Schematic ............... 71
Ordering Information ..................73
Product Part Numbers ........................ 73
General Comments ............................ 73
TABLE OF
CONTENTS

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
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 Qualied
• Compact size
• Class 2 output – 4dBm
• Low power operation
• UART interface
• PCM and SCO for external codec
• GPIO lines under AT control
• Support for Serial Port Prole
• Support for Health Device Prole (later release)
• Wi-Fi co-existence
APPLICATION AREAS
• Embedded Devices
• Phone Accessories
• Security Devices
• Medical and Wellness
Devices
• Automotive Applications
• Bluetooth®Advertising
• ePOS
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 exibility 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 Prole. The modules are fully qualied as
Bluetooth End Products, allowing designers to integrate them within their own products with no further Bluetooth
Qualication. They can then list and promote their products on the Bluetooth website free of charge.
Future releases include support for the Bluetooth Health Device Prole, making this module the ideal choice for
manufacturers who are developing Continua Health Alliance compliant devices.
A comprehensive AT command interface is included, which simplies rmware integration. Combined with a low
cost developers kit, this ensures that the choice of Laird Technologies Bluetooth modules guarantees the fastest
route to market.
OVERVIEW AND
KEY FEATURES

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BTM430/431
Bluetooth® AT Data Module
Categories Feature Implementation
Wireless Specication Bluetooth®Version 2.0+EDR
Transmit Class Class 2
Frequency 2.402 – 2.480 GHz
Channels 79 channels Frequency Hopping
Adaptive Frequency Hopping
Max Transmit Power +4 dBm at antenna pad – BTM430
+4 dBmi from integrated antenna – BTM431
Min Transmit Power -27 dBm at antenna pad – BTM430
-27 dBmi from integrated antenna – BTM431
Receive Sensitivity -84dBm
Range 30m
Data Transfer Rate Up to 300 kbps
Antenna Modes External Antenna 50 Ohm matched SMT pad – BTM430
Integrated Antenna (option) +0dBi multilayer ceramic – BTM431
UART Interface Serial Interface RS-232 bi-directional for commands and data
16550 compatible
Baud Rate Congurable from 1,200 to 921,600bps Non-standard
baud rates supported
Bits 8
Parity Odd, even, none
Stop bits 1
Default Serial parameters 9600,n,8,1
Levels Set by VDD_USB input
Modem Control DTR, DSR, DCD, RI, RTS, CTS
General Purpose Interface I/O 8 general purpose I/O pins
Audio Support 1 PCM channel @ 64kbps
SCO Channels Support SCO and eSCO
PCM Interface
Congurable as master or slave
8 bit A-law
8 bit μ-law
13 bit linear
PCM Clock available when in slave mode
Protocols and Firmware Bluetooth Stack V2.0 compliant. Fully integrated.
Proles
GAP (Generic Access Prole)
SDP (Service Discovery Prole)
SPP (Serial Port Prole)
FTP Client
OBEX push client
Firmware Upgrade Available over UART
Connection Modes Point to point (cable replacement)
SPECIFICATIONS

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
Categories Feature Implementation
Command Interface AT Instructions set Comprehensive control of connection and module operation
S Registers for non-volatile storage of parameters
Current Consumption Data Transfer Typically 32mA
Low Power Sniff Mode Less than 2.5mA
Supply Voltage Supply 3.0V – 3.3V DC
I/O 1.7V – 3.3V DC (independent of Supply)
USB & UART 1.7V – 3.6V DC (independent of Supply)
Coexistence / Compatibility WLAN (802.11) 2-wire and 3-wire hardware coexistence
schemes supported
Connections Interface Surface Mount Pads
External Antenna (BTM430) Pad for 50 Ohm antenna
Physical Dimensions 12.5mm x 18.0 x 3.4mm BTM430
12.5mm x 24.0mm x 3.4mm BTM431
Weight 3 grams
Environmental Operating Temperature -30°C to +70°C
Storage Temperature -40°C to +85°C
Approvals Bluetooth Qualied as an END product
FCC Limited Modular Approval (BTM430)
Full Modular Approval (BTM431)
CE & R&TTE Meets CE and R&TTE requirements
Miscellaneous Lead free Lead-free and RoHS compliant
Warranty 12 Months
Development Tools Development Kit
Development board and software tools
DVK-BTM430 Dev Kit with BTM430 module tted
DVK-BTM431 Dev Kit with BTM431 module tted
SPECIFICATIONS

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
Pin Signal Description Voltage
Specication
1 Unused
2 GND
3 UART_CTS Clear to Send I/P VUSB
4 UART_RXD Receive data I/P VUSB
5 UART_RTS Request to Send O/P VUSB
6 UART_TXD Transmit data O/P VUSB
7 GND
8 SPI_CSB SPI bus chip select I/P VIO
9 SPI_MISO SPI bus serial O/P VIO
10 SPI_MOSI SPI bus serial I/P VIO
11 SPI_CLK SPI bus clock I/P VIO
12 VDD_USB USB & UART supply voltage
13 VDD_IO I/O supply voltage
14 VDD_IN Main supply voltage
15 GND
16 PCM_IN PCM clock I/P VIO
17 PCM_SYNC PCM sync I/P VIO
18 PCM_CLK PCM clock I/P VIO
19 PCM_OUT PCM Data O/P VIO
20 RESET Module reset I/P See note 2
21 GPIO4 BT_ACTIVE / BT_STATE VIO
22 GPIO2 / UART_DCD I/O for host VIO
23 GND
24 Unused
25 Unused See note 3
26 Unused See note 3
27 Unused See note 3
28 GND See note 3
29 ANT (BTM430) Antenna connection (50 ohm matched) See note 3
30 GND See note 3
31 Unused See note 3
32 Unused See note 3
33 Unused See note 3
34 Unused See note 3
35 Unused See note 3
36 Unused See note 3
37 Unused See note 3
38 Unused
39 Unused
40 Unused
41 GND
42 GPIO1/ UART_RI I/O for host VIO
43 GPIO7 UART_DTR VIO
44 GPIO8 UART_DSR VIO
45 GND
46 D- Not used for AT module variants VUSB
47 D+ Not used for AT module variants VUSB
48 GPIO6 RF_ACTIVE VIO
49 GPIO5 WLAN_ACTIVE VIO
50 GPIO3 BT_PRIORITY VIO
Note: 1. Unused pins may have internal connections and must not be connected.
2. Reset input is active low. Input is pulled up to VDD_IN via 22k. Minimum reset pulse width is 5ms.
3. Pins 25-37 should be left not connected on modules with integrated antenna (BTM411, BTM421, and BTM431)
SPECIFICATIONS

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
OPERATING PARAMETERS
Recommended Operating Conditions
OPERATING CONDITION MIN MAX
VDD_USB
(USB compatibility not required) 1.7 3.6
VDD_USB
(USB compatibility required) 3.1 3.6
VDD_IO 1.7 3.3
VDD_IN 3.0 3.3
VOLTAGE SPECIFICATIONS
Logic Levels (VUSB)
INPUT VOLTAGE LEVELS MIN TYP MAX
Vih 0.7VDD_USB
Vil 2.7<VDD_USB<3.0 -0.4 +0.8
1.7<VDD_USB<1.9 -0.4 +0.4
OUTPUT VOLTAGE LEVELS (1.7<VDD_USB<1.9)
Voh (Iout = -4mA) VDD_USB – 0.4
Vol (Iout = 4mA) 0.4
OUTPUT VOLTAGE LEVELS (2.7<VDD_USB<3.0)
Voh (Iout = -4mA) VDD_USB – 0.2
Vol (Iout = 4mA) 0.2
Note: VDD_USB must be connected to power the USB and UART interfaces.
Logic Levels (VIO)
INPUT VOLTAGE LEVELS MIN TYP MAX
Vih 0.7VDD_IO
Vil 2.7<VDD_IO<3.0 -0.4 +0.8
1.7<VDD_IO<1.9 -0.4 +0.4
OUTPUT VOLTAGE LEVELS (1.7 < VDD_IO < 1.9)
Voh (Iout = -4mA) VDD_IO – 0.4
Vol (Iout = 4mA) 0.4
OUTPUT VOLTAGE LEVELS (2.7 < VDD_IO < 3.0)
Voh (Iout = -4mA) VDD_IO – 0.2
Vol (Iout = 4mA) 0.2
OPERATING
PARAMETERS

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
AT COMMAND SET
REFERENCE
This document describes the protocol used to control and congure the BTM430 and BTM431 Bluetooth Data
Modules.
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. Many 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 congured 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.
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.
Assumptions
The following assumptions are made:-
1. All commands are terminated by the carriage return character 0x0D, which is represented by the string
<cr> in descriptions below this cannot be changed.
2. 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>.
3. All Bluetooth addresses are represented by a xed 12 digit hexadecimal string, case insensitive.
4. All Bluetooth Device Class codes are represented by a xed 6 digit hexadecimal string, case insensitive.
5. All new Bluetooth specic commands are identied by the string +BTx, where x is generally a
mnemonic of the intended functionality.
AT Command Set Syntax
<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 which could be 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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BTM430/431
Bluetooth® AT Data Module
MODULE CONFIGURATION COMMANDS
This section describes AT commands associated with module conguration and control.
1. AT
Used to check the module is available.
Response: <cr,lf>OK<cr,lf>
2. 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
Response: <cr,lf>ERROR nn<cr,lf>
3. ATIn {Information}
This will return the following information about the Laird Technologies device.
I0 The product name/variant.
I1 The CSR rmware build number.
I2 The Laird Technologies rmware build number. For internal use only.
I3 The Laird Technologies rmware 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 part number.
I9 0 if not in a connect state and 1 if in a connect state.
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 prole <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
AT COMMAND SET
REFERENCE

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BTM430/431
Bluetooth® AT Data Module
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
I15 The maximum length of an AT command, including the terminating carriage return
I16 The codec output gain range
I17 The codec input gain range
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 signicant digit equates
to the value stored in S Register 512 or 555.
Note when n=16, ATI9 will return 1.
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 dened 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.
I10435 The value of the PCM_CONFIG32 parameter in the chipset database
I10438 The value of the PCM_FORMAT parameter in the chipset database
For recognized values of n. All other values of n will generate an error.
Response: <cr,lf>As Appropriate<cr,lf>OK<cr,lf>
or
Response: <cr,lf>ERROR nn<cr,lf>
AT COMMAND SET
REFERENCE

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BTM430/431
Bluetooth® AT Data Module
4. 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, inquiry delay time etc, as listed in detail below.
The value part ‘m’ can be entered as decimal or hexadecimal. A hexadecimal value is specied 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.
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 S Register 504 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 ‘^’.
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 prole when not specied explicitly in
the ATD command.
S102 1 1..$7F Denes a set of bits masks for enabling prole server support. With
the exception of Serial Port Prole, implementation of the prole
servers below requires implementation in the external host
processor and Bluetooth qualication of the completed server
implementation. Values can be ORed.
1 is Serial Port Prole
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 eld 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 proles are activated at the same time.
S103 1 1..7 Boot Mode on cold boot.
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.
AT COMMAND SET
REFERENCE

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BTM430/431
Bluetooth® AT Data Module
Register Default Range Comment
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 congured 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
specied 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.
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
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.
AT COMMAND SET
REFERENCE

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Bluetooth® AT Data Module
Register Default Range Comment
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 trafc 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 trafc 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 trafc 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 that 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 species the time in seconds
that the device will remain in the specied mode after power up.
On timeout, the device will fall back to the mode specied in S
Register 555.
In some rmware 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 congured 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
dened 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 specied. 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 lter to be used with AT+BTI when it is not
explicitly specied. When queried the value is always printed as a
hex number.
The seventh most signicant digit, can be 0,1 or 2, and is used to
specify the type of device class lter.
When 0, it species no ltering.
When 1, it species an AND mask and all 24 bits are relevant
When 2, it species a lter to look for devices with matching major
device class which occupies a 5 bit eld 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
AT COMMAND SET
REFERENCE

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BTM430/431
Bluetooth® AT Data Module
Register Default Range Comment
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
rmware 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 rmware 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 specied in this register. This value is rounded down
to the nearest 100ms
S520 Depends
on device
– see
comments
1200..115200 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: 1200,2400,4800,9600,19200,2
8800,38400,57600,115200.
If S register 525=1, then the maximum baud rate is limited to
115200
The default is 9600 for Laird Technologies’ BISM, Embedded
Modules and BTM43X devices and 115200 for other Laird
Technologies Bluetooth devices.
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 used for non-standard baud rates. For stan-
dard baud rates use S520.
The effect is immediate and in fact the OK will be sent at the new
baud rate.
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.
See S Register 526 for further information
S524 0 0..2 Parity. 0=None, 1=Odd, 2=Even
See S Register 526 for further information.
S526 3 1..3 This register species a 2 bit mask used to qualify how S Registers
520 to 524 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
So 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 congured as master in pure-cable-
replacement mode. This value is rounded down to the nearest
100ms. See S Register 505 and 543 also
AT COMMAND SET
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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
Register Default Range Comment
S531 0 0..5 Species 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 (Reserved for future use)
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.
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 connec-
tion, 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 specied 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.
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 conguration 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.
AT COMMAND SET
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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
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 com-
mand. 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 Congure the UART for either low latency or maximum
throughput. A setting of 1 gives maximum throughput.
S551 0x3211 0xFFFF This register species 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 RF-
COMM connection.
Nibble 0..3 species the source for RTC
4..7 species the source for RTR
8..11 species the source for DV (i.e. DCD)
12..15 species 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
4 If DSR (pin 10) is asserted then 1 otherwise 0
In the event that a nibble species 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.
S552 0x0122 0x0FFF This register species in each 4 bit nibble, how the DTR, DCD, RI
output pins are controlled when in a Bluetooth connection
Nibble 0..3 species the source for DTR
4..7 species the source for DCD
8..11 species 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
AT COMMAND SET
REFERENCE

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
Register Default Range Comment
S553 0x0201 0x0FFF This register species in each 4 bit nibble, how the DTR,DCD,RI
output pins are controlled when NOT in a Bluetooth connection
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.
Nibble 0..3 species the source for DTR
4..7 species the source for DCD
8..11 species 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 species 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.
S555 1 1..7 If S Register 554 is nonzero, then after the post reset window
expires, the mode will revert to the mode specied in this register.
This allows, for example, the device to be discoverable and
connectable on power up (mode 4 or 7) and on window timer
expiry to revert to connectable only (mode 3 or 6).
A power cycle, reset via BREAK or ATZ is required to see effects of
a change.
In some rmware 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 congured 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
dened by S Reg 568 and if deasserted then S Reg 569.
S556 0 0..3 Allows GPIO values to be read via the minor class eld in an inquiry
response.
When this value is non-zero, bits2 to 7 contain information as
follow:-
1 :- Unused
2 :- Unused
3 :- GPIO1 to GPIO6
Set to 0 to disable this feature.
This allows i/o information to be conveyed without a connection.
S557 32 4..900 Specied in seconds, the update interval for the feature enabled
via S Reg 556
S558 0 0..1 When 1, the following responses; “RING”, “NO CARRIER” and
“CONNECT” are replaced by “BTIN”, “BTDOWN” and “BTUP”
respectively. This will eliminate ambiguity when the module has
a Bluetooth connection to an AT modem which also gives these
responses.
AT COMMAND SET
REFERENCE

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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
Register Default Range Comment
S559 0 0..3 This species a mask.
When Bit 0 is 1, the response word “ERROR“ is replaced by
“BTERR” and “OK” is replaced by “ok”.
When Bit 1 is 1, then error responses do not include the error
number and instead the error number can be retrieved using
ATI12.
S560 15 15..120 Disconnect timeout in seconds. This timer species how long to
wait for conrmation from the peer device and/or the underlying
stack that the connection has been successfully torn down. There
can be instances where a conrmation does not arrive and so in
this case this timer is used to ‘close off’ the procedure and put the
state machine back into a proper mode for new operations.
Time is specied with 15 seconds intervals.
S561 0 0..1000 Sniff Attempt Time in units of milliseconds. 0 means disable.
See section “Power Consumption and Reset” in the user guide for
more details.
S562 0 0..1000 Sniff timeout Time in units of milliseconds. 0 means disable.
See section “Power Consumption and Reset” in the user guide for
more details.
S563 0 0..1000 Sniff Minimum Interval in units of milliseconds. 0 means disable.
See section “Power Consumption and Reset” in the user guide for
more details.
S564 0 0..1000 Sniff Maximum Interval in units of milliseconds. See section “Power
Consumption and Reset” in the user guide for more details.
S565 0 1 If set to 1, RI (Ring Indicate) line is congured as an input and
forces the start-up mode (SReg512) and post-timeout on Start-up
mode (SReg555) to be dependent on the state of RI. The RI condi-
tional modes are dened by SRegs 566 to 569 inclusive.
S566 1 7 If S565=1, and RI is asserted then this is the mode the device will
start up in.
S567 1 7 If S565=1, and RI is deasserted then this is the mode the device will
start up in.
S568 1 7 If S565=1, and RI is asserted then this is the mode the device will
assume after the post-start-up timeout dened in SReg 554 instead
of mode dened in SReg555
S569 1 7 If S565=1, and RI is deasserted then this is the mode the device will
assume after the post-start-up timeout dened in SReg 554 instead
of mode dened in SReg555
S582 0 0..1 FTP Related:
0 = BodyLen in PUT obex packet = 0
1 = BodyLen in PUT obex packet = 1
S583 0xB 0 .. 0x1F This species the initial state of the following modem control lines
sent to the peer
Bit 0 := RTC (DTR/DSR)
Bit 1 := RTR (RTS/CTS)
Bit 2 := IC (Ring Indicate RI)
Bit 3 := DV (DCD)
Bit 4 := FC (Reserved)
AT COMMAND SET
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Laird Technologies
BTM430/431
Bluetooth® AT Data Module
Register Default Range Comment
S584 0 0..1 Enable/Disable eSCO
When changing the unit returns ERROR 14 it implies the device is
either in a connection or waiting for a connection and so the new
value cannot be accepted. For the former, drop the
connection, then issue the command AT+BTX and then set the
new value and for the latter issue the command AT+BTX prior to
setting the register.
S585 0 0..8 Enable / disable GPIO PWM feature on specied GPIO pin. Set to
0 to disable the feature on all GPIO pins. PWM pulse width and
repetition are controlled by S registers 586 and 587.
S586 1000 100..5000 Pulse period in milliseconds (rounded down to nearest multiple
of 50)
S587 0 0..100 Duty cycle in percent (rounded to the nearest multiple of 4)
S588 0 0..1 After a disconnection, there will be a cold reset
S589 8 0..F Codec output gain
S590 1 0..3 Codec input gain
S591 0 0..1FF Default GPIO output states when not in a connection. This is used
when virtual digital i/o cable replacement mode is in operation
S592 0 0..1 Set this to 1 to reduce the trusted device database to just 1 record
when autosaving of pairing is enabled via S reg 538
S593 0 0..1 Automatically append last 6 digits of local bluetooth address to the
friendlyname which was set via AT+BTN or AT+BTF
S594 0 0..1 Set handsfree prole version in sdp record. Set to 0 for 1.1 and
to 1 for 1.5. Allows SDP record to be manipulated when host
implements handsfree prole.
S595 1 0..1 Set handsfree gateway prole version in sdp record. Set to 0 for
1.1 and to 1 for 1.5. Allows SDP record to be manipulated when
host implements handsfree prole.
S596 0 1..1FF Audio Gateway features to be advertised in SDP record. See
handsfree prole specication for exact bit mapping. Allows SDP
record to be manipulated when host implements handsfree prole.
S597 0 0..2 Audio gateway Mode: set to 0 for SDP record advert only. No
other values for this register are currently approved.
S600 ? 0..65535 Number of times this module has gone through a reset cycle. This
feature is enabled by S Reg 601.
Writing any value to this register will initialise it to a certain value
S601 0 0..1 If this is 1, then on reset S Reg 600 value will be incremented.
S610 0 0..7FFF Set direction of digital I/O lines. This is a mask made up of 8 bits.
Setting a bit to 1 makes that I/O line an output. GPIO1 is bit 0,
GPIO2 is bit 1, up to bit 7 for GPIO8.
S611 0 1 Set to 1 to invert the logic of GPIO outputs. For example,
ATS621=1 will set the output pin to low and vice versa.
S620 n/a 0..255 Read/Write to all 8 Digital lines in one atomic step. The value is
returned as a 4 digit hexadecimal value with trailing 0s.
S621 n/a 0..1 Read/Write to GPIO1
S622 n/a 0..1 Read/Write to GPIO2
S623 n/a 0..1 Read/Write to GPIO3
S624 n/a 0..1 Read/Write to GPIO4
S625 n/a 0..1 Read/Write to GPIO5
AT COMMAND SET
REFERENCE