Laird BTM510 User manual

BTM510/511
MULTIMEDIA MODULE
USER MANUAL
Innovative Technology
for a Connected World
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Laird Technologies
BTM510/511
Bluetooth® Multimedia Module
CONTENTS
BTM510/511 Bluetooth®Module ..3
Overview .............................................. 3
BTM510/511 Key Features ................... 3
Specications ................................4
Detailed Specications ......................... 4
Pin Denitions ...................................... 6
Operating Parameters ...................8
Voltage Specications .......................... 8
Notes for PCB Layout ........................... 8
Conguring the BTM510/511 ........9
References ........................................... 9
Glossary of Terms ............................... 10
AT Command Set .............................. 11
Assumptions ...................................... 11
Commands ........................................ 11
General AT Commands ..................... 11
General Bluetooth®Control ............... 22
Hardware Unit Control ....................... 28
Bluetooth® Proles ............................. 30
Secure Simple Pairing ......................... 37
Link Key Management ....................... 37
Miscellaneous...................................... 38
Appendix ........................................... 39
BT-MM Unsolicited Messages ............ 39
BT-MM Error Responses ..................... 39
Mechanical Drawings ..................41
Mechanical Details ............................. 41
Recommended PCB Footprint ............ 41
Diagrams ............................................ 42
Ordering Information ..................45
Product Part Numbers ........................ 45
General Comments ............................ 45
TABLE OF
CONTENTS

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Laird Technologies
BTM510/511
Bluetooth® Multimedia Module
The BTM510 and BTM511 are low-power Bluetooth®modules designed for adding robust
audio and voice capabilities. Based on the market-leading Cambridge Silicon Radio BC05
chipset, these modules provide exceptionally low power consumption with outstanding range.
Supporting the latest Bluetooth Version 2.1+EDR specication, these modules provide the
important advantage of secure simple pairing that improves security and enhances easy use.
At only 14mm x 20mm, the compact size of the BTM510 makes it ideal for battery-powered
or headset form factor audio and voice devices. With a 16-bit stereo codec and microphone
inputs to support both stereo and mono applications, these modules also contain a full,
integrated Bluetooth-qualied stack along with SPP, HFP 1.5, HSP, AVRCP, and A2DP
proles. Customers using these modules may list and promote their products free of charge
on the Bluetooth website.
The BTM510/511 modules include an embedded 32-bit, 64-MIPS DSP core within the BC05.
This is integrated with the Bluetooth functionality which allows designers to add signicant
product enhancements including features such as echo cancellation, noise reduction, and
audio enhancement using additional soft codecs. The availability of the 16MB of ash memory
in the module allows complex functionality to be included. DSP routines can be licensed
through a number of specialist partners. Typical applications for these modules include
Bluetooth stereo headsets, VoIP phones, and wireless audio links.
To speed product development and integration, Laird Technologies has developed a
comprehensive AT command interface that simplies application development, including
support for audio and headset functionality. Access to GPIO pins allows mapping for direct
connection to actuator buttons on headsets. Combined with a low-cost development kit,
Laird Technologies’ Bluetooth®modules provide faster time to market.
FEATURES
• Fully featured Bluetooth®multimedia module
• Bluetooth®v2.1+EDR
• Supports mono and stereo
headset applications
• Adaptive Frequency Hopping to cope with
interference from other wireless devices
• 32bit Kalimba DSP for enhanced
audio applications
• Support for Secure Simple Pairing
• External or internal antenna options
• HSP, HFP, A2DP, and AVRCP audio proles
• 16-bit stereo codec and microphone input
• Integrated audio ampliers for driving
stereo speaker
• Comprehensive AT interface for
simple programming
• Bluetooth END product qualied
• Compact size
• Class 2 output – 4dBm
• Low power operation
• Wi-Fi co-existence hardware support
APPLICATION AREAS
• High-quality stereo headsets
• Mono voice headsets
• Hands-free devices
• Wireless audio cable replacement
• MP3 and music players
• Phone accessories
• VoIP products
• Cordless headsets
• Automotive
OVERVIEW AND
KEY FEATURES

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BTM510/511
Bluetooth® Multimedia Module
CATEGORIES FEATURE IMPLEMENTATION
Wireless Specication Standards Supported Bluetooth®v2.1 + EDR
Transmit Class Class 2
Frequency 2.402 – 2.480 GHz
Channels 79 channels Frequency Hopping Adaptive Frequency Hopping
Max Transmit Power +4 dBm @ antenna pad – BTM510
+4 dBmi from integrated antenna – BTM511 (provisional)
Min Transmit Power -27 dBm @ antenna pad – BTM510
-27 dBmi from integrated antenna – BTM511 (provisional)
Receive Sensitivity Better than -86 dBm
Data Transfer rate Up to 300kbps
Range Up to 50 meters free space (Data)
Antenna Modes External Antenna 50 Ohm matched SMT pad – BTM510
Integrated Antenna +0dB (provisional) multilayer ceramic – BTM511
UART Interface Serial Interface RS-232 bi-directional for commands and data 16550 compat-
ible
Baud Rate Congurable from 1,200 to 921,600bps
Non-standard baud rates supported
Bits 8
Parity Odd, even, none
Stop bits 1 or 2
Default Serial parameters 9,600,n,8,1
Levels Set by VDD_USB pin
Modem Control DTR, DSR, DCD, RI, RTS, CTS
General Purpose Interface I/O 8 general purpose I/O pins
I2S Stereo Audio Digital Interface Bus
LED Two
Audio Codec Integrated stereo codec with -95dB SNR for DAC
Ampliers Direct drive for 22ΩMono Speaker / 44ΩStereo Speakers
Microphone Input with bias for low noise microphone
Sample Rates (DAC & ADC) 8, 11.025, 16, 22.05, 32 & 44.1kHz
Protocols & Firmware Bluetooth®Stack V2.1 compliant. Fully integrated.
Proles GAP (Generic Access Prole)
SDP (Service Discovery Prole)
SPP (Serial Port Prole)
HSP
HFP – Audio Gateway and Handsfree
A2DP – Source and Sink
AVRCP – Target and Controller
Protocols RFCOMM
AVCTP
AVDTP
Firmware Upgrade Available over UART
SPECIFICATIONS

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Laird Technologies
BTM510/511
Bluetooth® Multimedia Module
CATEGORIES FEATURE IMPLEMENTATION
Command Interface AT Instruction set Comprehensive control of connection and module operation,
including extensions for Audio control.
Direct mapping of GPIO to audio functions, e.g. Play, Volume,
etc.
S Registers for non-volatile storage of parameters
DSP Kalimba DSP Integrated in BC05 32bit, 64MIPS, 16Mbps Flash Memory
(shared)
Applications Available from partners
Current Consumption Data Transfer Typically < 35mA
Stereo Music Typically < 70mA (including speaker drive)
Low Power Sniff Mode Less than 1.5mA
Supply Voltage Supply 3.0V – 3.6V DC
I/O 1.7V – 3.6V DC
USB 1.7V – 3.6V DC
Coexistence / Compatibility WLAN (802.11) 2-wire and 3-wire hardware coexistence schemes supported
Connections External Antenna (option) Pad for 50 Ohm antenna – BTM510
Interface Surface Mount Pads
Physical Dimensions 14.0mm x 20.0 x 1.6mm - BTM510
14.0mm x 26.0mm x 1.6mm - BTM511 (provisional)
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 Meets FCC requirements
Modular Approval (Integrated Antenna option – BTM511)
CE & R&TTE Meets CE and R&TTE requirements
Miscellaneous Lead free Lead-free within EU requirements and RoHS compliant
Warranty 12 Months
Development Tools Development Kit Development board and software tools
SPECIFICATIONS
CATEGORIES FEATURE IMPLEMENTATION
Wireless Specication Standards Supported Bluetooth®v2.1 + EDR
Transmit Class Class 2
Frequency 2.402 – 2.480 GHz
Channels 79 channels Frequency Hopping Adaptive Frequency Hopping
Max Transmit Power +4 dBm @ antenna pad – BTM510
+4 dBmi from integrated antenna – BTM511 (provisional)
Min Transmit Power -27 dBm @ antenna pad – BTM510
-27 dBmi from integrated antenna – BTM511 (provisional)
Receive Sensitivity Better than -86 dBm
Data Transfer rate Up to 300kbps
Range Up to 50 meters free space (Data)
Antenna Modes External Antenna 50 Ohm matched SMT pad – BTM510
Integrated Antenna +0dB (provisional) multilayer ceramic – BTM511
UART Interface Serial Interface RS-232 bi-directional for commands and data 16550 compat-
ible
Baud Rate Congurable from 1,200 to 921,600bps
Non-standard baud rates supported
Bits 8
Parity Odd, even, none
Stop bits 1 or 2
Default Serial parameters 9,600,n,8,1
Levels Set by VDD_USB pin
Modem Control DTR, DSR, DCD, RI, RTS, CTS
General Purpose Interface I/O 8 general purpose I/O pins
I2S Stereo Audio Digital Interface Bus
LED Two
Audio Codec Integrated stereo codec with -95dB SNR for DAC
Ampliers Direct drive for 22ΩMono Speaker / 44ΩStereo Speakers
Microphone Input with bias for low noise microphone
Sample Rates (DAC & ADC) 8, 11.025, 16, 22.05, 32 & 44.1kHz
Protocols & Firmware Bluetooth®Stack V2.1 compliant. Fully integrated.
Proles GAP (Generic Access Prole)
SDP (Service Discovery Prole)
SPP (Serial Port Prole)
HSP
HFP – Audio Gateway and Handsfree
A2DP – Source and Sink
AVRCP – Target and Controller
Protocols RFCOMM
AVCTP
AVDTP
Firmware Upgrade Available over UART

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Laird Technologies
BTM510/511
Bluetooth® Multimedia Module
PIN SIGNAL DESCRIPTION VOLTAGE
SPECIFICATION
1 PIO15 / DTR Host I/O VIO
2 PIO5/BT_STATE/BT_PRIORITY Host I/O, BT Co-existence VIO
3 PCM_IN PCM Data I/P VIO
4 PCM_OUT PCM Data O/P VIO
5 PCM_SYNC PCM Sync I/P VIO
6 PCM_CLK PCM CLK I/P VIO
7 LED_EXT1 Host I/O See Note 2
8 LED_EXT0 Host I/O See Note 2
9 GND
10 VDD_USB USB supply voltage
11 VDD_IO I/O supply voltage
12 VDD_IN Main supply voltage
13 GND
14 SPI_CSB SPI bus chip select I/P VIO
15 SPI_MISO SPI bus serial O/P VIO
16 SPI_CLK SPI bus clock I/P VIO
17 SPI_MOSI SPI bus serial I/P VIO
18 PIO2/DSR Host I/O VIO
19 PIO3/RI Host I/O VIO
20 PIO1/DCD Host I/O VIO
21 PIO0/BT_ACTIVE Host I/O, BT Co-existence VIO
22 GND
23 AUDIO_GND Audio ground
24 SPKR_A_N Speaker, channel A- (left) See note 3
25 SPKR_A_P Speaker, channel A+ (left) See note 3
26 SPKR_B_N Speaker, channel B- (right) See note 3
27 SPKR_B_P Speaker, channel B+ (right) See note 3
28 MIC_BIAS Microphone bias See note 4
29 MIC_BP_C Microphone, channel A- (left) See note 4
30 MIC_BN_C Microphone, channel A+ (left) See note 4
31 MIC_AP_C Microphone, channel B- (right) See note 4
32 MIC_AN_C Microphone, channel B+ (right) See note 4
33 Unused
34 ANT Antenna connection – BTM510 (50 ohm matched)
35 Unused
36 Unused
37 Unused
38 Unused
39 Unused
40 Unused
41 Unused
42 Unused
43 Unused
44 Unused
45 USB_D- VUSB
46 USB_D+ VUSB
47 GND
48 UART_RTS Request to Send O/P VUSB
49 UART_CTS Clear to Send I/P VUSB
50 UART_TX Transmit data O/P VUSB
51 UART_RX Receive data I/P VUSB
52 PIO7/RF_ACTIVE Host I/O, BT Co-existence VIO
53 PIO6/WLAN_ACTIVE Host I/O, BT Co-existence VIO
54 Reset Module reset I/P See Note 1
SPECIFICATIONS

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BTM510/511
Bluetooth® Multimedia Module
SPECIFICATIONS
The voltage on the module pad should be maintained below 0.5V
in which case the Ron of the FET is around 20Ω. Provided that this
condition is met, then the current owing through the diode is:
3. The speaker output is capable of driving loads with a minimum
impedance of 16Ωdirectly.
4. The audio inputs can operate in either line input mode or microphone
mode. The input circuit has a two stage amplier – the rst stage
provides a xed 24dB gain and the second a variable gain of
between -3dB and 18dB. If an input gain of less than 24dB is selected,
then the rst stage is switched out and the module is operating in line
input mode.
Iled =VDD - VFWhere VFis the forward bias voltage of the LED.
R + 20
When operating in microphone mode the
microphone should be biased as follows:
MIC_AP
MIC_AN
Module
External Circuit
External Circuit
MIC_BIAS
15nH
15pF
15nH
15pF
The input impedance on the microphone inputs (in microphone mode) is typically 6kΩ. In order to
maintain the regulation on the MIC_BIAS pin, the current drawn must be in the range 0.2 – 1.23mA.
If the microphone draws less current than this, then an additional resistor to ground must be added to
pre-load the microphone output. The audio input is designed for use with inputs of between 1μA
and 10μA at 94dB SPL. If the biasing resistors are set to 1kΩ, this implies a microphone with a
sensitivity in the range -40dBV to -60dBV.
The low pass lter elements formed by the inductor and capacitor are required to eliminate RF pick
up on the microphone inputs and should be placed as close to the module as possible.
When operating in line input mode, the input can be connected directly to the module input pins
in either single or double ended conguration as follows:
AC AC
Single ended Double ended
Note: 1. Reset input is active low. Input is pulled up to VDD_IN via 22k.
Minimum reset pulse width is 5ms.
2. LED drive pins are open drain outputs and hence the external circuit
to the right should be used.
VDD
Module External Circuit
R

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BTM510/511
Bluetooth® Multimedia Module
NOTES FOR PCB LAYOUT:
1. The RF output pin must be matched to a 50Ωstrip-line or coplanar waveguide on the antenna-less version (BTM510).
2. Ensure that there are no exposed conductors under the module to avoid shorts to the test points on the module underside.
3. ThePCBfootprintisprovidedforguidanceonly.UsersmaywishtomodifythePCBlanddimensionstosuittheirspecic
manufacturing or process.
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 3.6
VOLTAGE SPECIFICATIONS
LOGIC LEVELS (VUSB)
Input Voltage Levels Min Typ Max
Vih 0.625VDD_USB VDD_USB+0.3
Vil -0.3 0.25VDD_USB
Output Voltage Levels
Voh (Iout = -4mA) 0.75VDD_USB VDD_USB
Vol (Iout = 4mA) 0 0.125
LOGIC LEVELS (VIO)
Input Voltage Levels Min Typ Max
Vih 0.625VDD_IO VDD_IO+0.3
Vil -0.3 0.25VDD_IO
Output Voltage Levels
Voh (Iout = -4mA) 0.75VDD_IO VDD_IO
Vol (Iout = 4mA) 0 0.125
LOGIC LEVELS (VUSB – USB TERMINALS D+, D-)
Input Voltage Levels Min Typ Max
Vih 0.7VDD_USB
Vil 0.3VDD_USB
Output Voltage Levels (to correctly terminated USB cable)
Voh 2.8 VDD_USB
Vol 0 0.2
OPERATING
PARAMETERS

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BTM510/511
Bluetooth® Multimedia Module
INTRODUCTION
This document describes the protocol used to control and congure the BTM Bluetooth device.
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.
Just like telephony modems, Laird Technologies’ devices power up in an unconnected state and will only
respond via the serial interface. In this state, the 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 conguration of the device 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 (default
setting is 9600) 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.
AT COMMAND SET
REFERENCE

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BTM510/511
Bluetooth® Multimedia Module
GLOSSARY OF TERMS
Description
A2DP : Advanced Audio Distribution Prole
ACL : Asynchronous Connection-Oriented Link
ADC :Analogue to Digital Converter
AGHFP : Audio Gateway Hands-Free Prole
AT : Command prex, ‘Attention’
AVRCP : Audio/Video Remote Control Prole
BISM :Bluetooth Intelligent Serial Module
CoD : Class Of Device (also referred to as “device class”)
Codec :Device capable of encoding / decoding an analogue / digital signal
DAC :Digital to Analogue Converter
DSP :Digital Signal Processor
DUN : Dial-Up Network Prole
EIR :Extended Inquiry Response
eSCO : Enhanced Synchronous Connection Oriented Link (used for Audio)
FTP : File Transfer Prole
GOEP : Generic Object Access Exchange Prole
GPIO :General Purpose Input Output
HF : Hands-free Role of Hands-free Prole (“Hands-free Unit”)
HFG : Audio Gateway Role of Hands-free Prole (“Hands-free Gateway”)
HFP : Hands Free Prole
HID : Human Interface Device Prole
HS : Headset Role of Headset Prole (“Headset”)
HSG : Audio Gateway Role of Headset Prole (“Headset Gateway”)
HSP : Headset Prole
I/O (IO) : Input/Output
Mic :Microphone
MITM :Man In The Middle
OPP : Object Push Prole
PBAP : Phone Book Access Prole
PT :PASS THROUGH Command
PWM :Pulse Width Modulation
SBC : Sub Band Codec
SCO : Synchronous Connection Oriented Link (used for Audio)
SLC :Service Level Connection
SPP : Serial Port Prole
SSO :Serial Stream Oriented
SSP :Secure Simple Pairing
SUI :SUBUNIT INFO Command
Sxxx :S-Register No. xxx
TDL :Trusted Device List
UART :Universal Asynchronous Receiver / Transmitter
UI :UNIT INFO Command
AT COMMAND SET
REFERENCE

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BTM510/511
Bluetooth® Multimedia Module
OVERVIEW OF THE BTM PRODUCT FAMILY
BTM410 / BTM411
Chipset CSR BC4-Ext
Bluetooth version 2.1
Features SSP, EIR, SCO (1), eSCO (1)
Proles SPP
(1) external codec required
BTM510 / BTM511
Chipset CSR BC5MM-Ext
Bluetooth version 2.1
Features SSP, EIR, SCO, eSCO
Proles SPP, A2DP, AVRCP,HSP,HFP,DUN(DT)
BTM520 / BTM521
Chipset CSR BC5MM-Ext
Bluetooth version 2.1
Features SSP, EIR, SCO, eSCO
Proles SPP, A2DP, AVRCP,HSP,HFP,DUN(DT)
AT COMMAND SET
REFERENCE

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BTM510/511
Bluetooth® Multimedia Module
BTM - AT COMMAND SET
This section describes the AT Command Set for a BTM module. This section is structured in functional
groups of AT commands related to module conguration, Bluetooth proles, hardware units and
miscellaneous purposes.
Assumptions
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 BTM 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 six digit hexadecimal string, case insensitive.
5. All prole specic commands are identied by the prex shown in Table 3.1
Prole Term AT-Command Prex
Serial Port Prole SPP AT+SP…
Advanced Audio Distribution Prole A2DP AT+AP…
Audio/Video Remote Control Prole AVRCP AT+AV…
Headset Prole HSP AT+HS…
Hands-Free Prole HFP AT+HF…
Dial-Up Network Prole DUN AT+DU…
Table 3.1: AT Command prex for proles
Command Syntax
The following syntax is employed throughout this document to describe optional or mandatory parameters for
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 six 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 four character UUID number consisting of ASCII characters ‘0’ to ‘9’, ‘A’ to ‘F’ and ‘a’ to ‘f’.
General AT Commands
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>
AT COMMAND SET
REFERENCE

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Bluetooth® Multimedia Module
3. ATZ<n> {Hardware Reset and Emerge Into Boot Mode ‘n’}
Forces the device through a hardware reset which means it will eventually come alive in the local
command and unconnected mode. This allows changes to the non-volatile memory to take effect.
The module will issue an OK response after the reset is complete and it is ready to receive commands
once again.
ATZ and ATZ0 signify reset and emerge into the current boot mode (see command ATI14). ATZ1 to ATZ4
instructs the module to reset and then emerge into the appropriate boot mode. Note that S Register 103
species the boot mode from cold.
Boot modes are required to congure some low level device settings which cannot be congured by
S registers and AT commands. Currently there are predened settings dening the PCM data format
to be used with certain codec ICs (applies mainly to BC04).
Response after reset: <cr,lf>OK<cr,lf>
4. AT+BTC<devclasshex> {Set Device Class Code Temporarily}
This command is used to set the device class code which will be sent in subsequent inquiry responses.
It can be read back using the AT+BTC? Command, as described below.
<devclass> is a six digit hexadecimal number derived as per “Bluetooth Assigned Numbers” [8].
The 24 bits are made of four elds briey described as follows (bit 0 corresponds to the least
signicant bit):-
Bits 0-1: Format Type. This eld currently only has a value of 00 (i.e.,
format type 1).
Bits 2-7: Minor Device Class: The value of these six bits is interpreted
differently based on the Major Device Class stored in the next
ve bits.
Bits 8-12: Major Device Class: Five bits, refer to Figure 1 and Table 3 in
“Bluetooth Assigned Numbers” [8].
Bits 13-23: Major Service Class: 11 bit eld, used as a mask to dene
service classes, refer to Figure 1 and Table 2 in “Bluetooth
Assigned Numbers” [8].
Laird Technologies devices do not map to any predened Major Service Class or Major Device Class and
so the default devclass as shipped is 001F00, which means no Major Service Class and “Unclassied”
Major Device class.
Other examples of device class codes are follows:
Code (Hexadecimal) Name Major Service Major Device Minor Device
0x001F00 Unclassied None Unclassied n/a
0x200404 Headset Audio Audio Headset
There is a tool available in the Internet for creating a particular device class code: refer to [9].
A device class set by AT+BTC becomes visible immediately but will be lost on next power cycle.
Response: <cr,lf>OK<cr,lf>
Or for an invalid <devclass> value (usually a value which is not 6 hexadecimal characters long):
Response: <cr,lf>ERROR 08<cr,lf>
5. ATS515=<devclasshex> {Set Device Class Code Permanently}
S Register 515 is used to set the device class code permanently. Use AT&W to save the setting to
non-volatile memory. The new value will become visible on next power cycle which can be initiated
by ATZ. Refer to number 4 for more information about the device class code.
Response: <cr,lf>OK<cr,lf>
6. AT+BTC? {Read Device Class Code}
This command is used to read the current device class code.
Response: <cr,lf>123456
<cr,lf>OK<cr,lf>
AT COMMAND SET
REFERENCE

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Bluetooth® Multimedia Module
7. AT+BTF=”<string>” {Set Friendly Name Temporarily}
This sets the friendly name of this device as seen by other devices. The new name becomes immediately
visible. Any name set by this command will be lost on next power cycle.
Please refer to S register 593 (Table 4.1) too.
Response: <cr,lf>OK<cr,lf>
8. AT+BTN=”<string>” {Set Friendly Name Permanently}
This sets the default friendly name of this device as seen by other devices. It will be stored in non-volatile
memory. The new name will become visible to other devices on next power cycle. Use AT+BTF to make
the name visible immediately. Use AT+BTN? to read it back. An empty string (“”) will delete the string
from non-volatile memory which will force the default name to be used which is “Laird BTM 789012”.
The digits in the default friendly name represent the last six digits of the local Bluetooth address.
Please refer to S register 593 (Table 4.1) too. If a new value of S593 needs to be retained permanently,
save it to non-volatile memory by “AT&W”.
Response: <cr,lf>OK<cr,lf>
9. AT+BTN? {Read Friendly Name from Non-volatile Memory}
Read the default friendly name from non-volatile memory.
Response: <cr,lf>”My Friendly Name”<cr,lf>
<cr,lf>OK<cr,lf>
10. AT+BTF<bd_addr> {Get Remote Friendly Name}
This command gets the remote friendly name of the peer specied.
Response: <cr,lf><bd_addr>,”Friendly Name”
<cr,lf>OK<cr,lf>
11. AT+BTP {Make Device Discoverable and Connectable }
Make the device discoverable and connectable and wait for a connection from any device.
The setting remains valid until next reset or power cycle (unless not changed by any other AT command
subsequently). For permanent discoverable/connectable settings, please refer to S Register 512.
Response: <cr,lf>OK<cr,lf>
12. AT+BTQ {Make Device Discoverable}
Make the device discoverable but not connectable. Being discoverable implies that this device will
respond to inquiries from other devices (inquiry scans enabled).
The setting remains valid until next reset or power cycle (unless not changed by any other AT command
subsequently). For permanent discoverable/connectable settings, please refer to S Register 512.
Use AT+BTX to make the device not discoverable.
Response: <cr,lf>OK<cr,lf>
13. AT+BTG {Make Device Connectable}
Make the device connectable but not discoverable and wait for a connection from any device.
The setting remains valid until next reset or power cycle (unless not changed by any other AT command
subsequently). For permanent discoverable/connectable settings, please refer to S Register 512.
Response: <cr,lf>OK<cr,lf>
AT COMMAND SET
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14. AT+BTV<bd_addr>,<uuid> {SDP Query for Service }
This command is used to interrogate the SDP database of the peer device <bd_addr> for the service
<uuid>. It results in an ACL connection and then an SDP transaction.
If the <uuid> service is present then
Response: <cr,lf>0
<cr,lf>OK<cr,lf>
If the <uuid> service is not present then
Response: <cr,lf>1
<cr,lf>OK<cr,lf>
If the device < bd_addr > cannot be reached, or is in non-connectable mode then
Response: <cr,lf>2
<cr,lf>OK<cr,lf>
If the SDP database is corrupt or invalid then
Response: <cr,lf>3
<cr,lf>OK<cr,lf>
If the device is not in idle mode then
Response: <cr,lf>4
<cr,lf>OK<cr,lf>
and in this case, the command AT+BTX may put the device into the correct idle mode.
15. ATIn {Information}
This will return the information about the Laird Technologies device and its status. Please refer to
Table 4.2 (Appendix) for a complete list of supported ATIn parameters.
For recognized values of n:
Response: <cr,lf>As Appropriate<cr,lf>OK<cr,lf>
For unrecognized values of n.
Response: <cr,lf>Laird Technologies Inc, UK, (c)2009<cr,lf>
AT Commands for S Registers
As with modems, the Bluetooth module employs a concept of registers which are used to store parameters,
such as escape sequence character, inquiry delay time, etc.
For a list of general S registers please refer to page 17 and Table 4.1.
S registers associated with a particular prole or specic functions, are described in the appropriate prole
section of this document.
The following AT commands allow the manipulation of S registers.
1. ATSn=m {Set S Register}
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.
2. ATSn? {Read S Register Value}
This will return the current value of register n.
For recognized values of n
Response: <cr,lf>As Appropriate<cr,lf>OK<cr,lf>
For unrecognized values of n
Response: <cr,lf>ERROR nn<cr,lf>
AT COMMAND SET
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3. ATSn=? {Read S Register – Valid Range}
This will return the valid range of values for register n.
For recognized values of n
Response: <cr,lf>Sn:(nnnn..mmmm)<cr,lf>OK<cr,lf>
For unrecognized values of n
Response: <cr,lf>ERROR nn<cr,lf>
4. AT&Fn {Set S Register Defaults}
This command will only work when the device is in local command and unconnected mode.
Depending on the value of ‘n’, it installs S Register values appropriate for various power modes
ranging from minimum power consumption to maximum.
Legal values of ‘n’ are as per the following table. All other values of n will generate a syntax error
response. If ‘n’ is not specied then a default value of 0 is assumed where the baud rate is
NOT changed.
&F0 (Default) Medium power consumption, UART baud rate unchanged
&F1 Minimum power consumption, UART baud rate set to 9600
&F2 Minimum power consumption, UART baud rate set to 38400
&F3 Minimum power consumption, UART baud rate set to 115200
&F4 Medium power consumption, UART baud rate set to 115200
&F5 Maximum power consumption, UART baud rate set to 115200
The new values are NOT updated in non-volatile memory until the AT&W command is sent to
the device.
Response: <cr,lf>OK<cr,lf>
Or
Response: <cr,lf>ERROR nn<cr,lf>
5. AT&F* {Clear Non-Volatile Memory}
The AT&F* variant of the command installs values in S registers as per command AT&F4 and then
all other user parameters in non-volatile memory are erased. This means that the trusted device
database is cleared, and so are parameters related to the following commands: AT+BTR, AT+BTN,
AT+BTS.
Response: <cr,lf>OK<cr,lf>
Or
Response: <cr,lf>ERROR nn<cr,lf>
6. AT&F+ {Clear Non-Volatile Memory}
This command erases all user parameters in non-volatile memory except S Registers 520 to 525.
This means that the trusted device database is cleared, and so are parameters related to the following
commands: AT+BTR, AT+BTN, AT+BTS.
Response: <cr,lf>OK<cr,lf>
Or
Response: <cr,lf>ERROR nn<cr,lf>
7. AT&W {Write S Registers to Non-Volatile Memory}
Writes current S Register values to non-volatile memory so that they are retained over a power cycle.
Response: <cr,lf>OK<cr,lf>
Or
Response: <cr,lf>ERROR nn<cr,lf>
AT COMMAND SET
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General S Registers
Please refer to Appendix, Table 4.1 for a list of supported S Registers.
The main purpose of S Registers is to make the device conguration persistent. All S Registers can be saved to
non-volatile memory by AT&W.
In some cases, an AT command and an S register exist for one and the same setting. In the majority of those
cases the AT command’s setting will be lost on next power cycle whereas the S register can be saved and is still
available after power cycle. This rule applies to many but not to all of those cases.
AT Commands for Inquiry
1. AT+BTI<devclass> { Inquire}
This will make the device perform an inquiry for delay seconds and max number of unique responses,
where delay is dened by S register 517 and max is specied by S register 518.
The <devclass> is an optional parameter where the value species either a six digit device class code or
a two digit major device class. If it is not specied, the value is taken from S register 516.
When <devclass> is six hexadecimal characters long, it species an AND mask which is used to lter
inquiry responses. When <devclass> is two hexadecimal characters long, it forces the inquiry to lter
responses to devices that match their major device class code to this value – which can only be in
the range 00 to 1F.
The response format to AT+BTI is dened by S Register 330 by bitmask. This is device address, device
class, friendly name, receiver strength indicator and extended inquiry data. Please refer to Figure 3.1
and Table 3.2.
For S330=1:
Response: <cr,lf>12346789012
<cr,lf>12345678914
<cr,lf>OK<cr,lf>
A Bluetooth inquiry process is such that for a single inquiry request a device could respond many times.
To ensure that an address is sent to the host only once for a particular AT+BTI, an array of addresses is
created at the start of each AT+BTI and is lled as responses come in. This array of addresses is stored
in dynamic memory and as such if the memory allocation fails then the inquiry procedure is aborted and
in that case an error response is sent to the host. To clarify, a single AT+BTI will never return the same
Bluetooth address more than once. But as long as the responding device is active, all AT+BTI commands
will always return it.
As the inquiry process is driven by randomness, it is not guaranteed that each discoverable device is
always found on the rst attempt. Sometimes more than one inquiry processes might be necessary
to nd a particular device. The probability also depends on the inquiry scanning intervals of the device
being searched for.
The inquiry process can be sped up if the friendly name is not required (ag not set in S330) as part of
the inquiry response or if a <dev_class> lter is used.
Bit76543210
Reserved for future usage EIRD RSSI FN COD ADR
Default 0 0 0 0 0 0 0 1
Figure 3.1: S Register 330 controlling inquiry response format
Field Description
0 – ADR 1 – display Bluetooth device address on inquiry result
0 – do not display Bluetooth device address on inquiry result; if any further bit is set, a comma is inserted as
separator
1 – COD 1 – display class of device on inquiry result
0 – do not display class of device on inquiry result; if any further bit is set, a comma is inserted as separator
2 – FN 1 – display friendly name on inquiry result
0 – do not display friendly name on inquiry result; if any further bit is set, a comma is inserted as separator
3 – RSSI 1 – display RSSI value on inquiry result
0 – do not display RSSI value on inquiry result; if any further bit is set, a comma is inserted as separator
4 – EIRD 1 – display eird on inquiry result
0 – do not display eird on inquiry result
Table 3.2: Field Descriptions for S Register 330
AT COMMAND SET
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Inquiry Response Format
The format of an inquiry result will be:
<cr,lf><bd_addr>,<dev_class>,<friendly_name>,<rssi>,<eir_data><cr,lf>
<bd_addr> = 12 digit, hexadecimal;
<dev_class> = six digit, hexadecimal;
<friendly_name> = printable ASCII character, enclosed by ‘ “ ‘
<rssi> = signed two digits decimal
<eir_data> = printable ASCII character whenever possible, otherwise a byte is displayed as ¬2 digit
hexadecimal with preceding ‘\’, enclosed by ‘ “ ‘
For example the data block 01 41 42 43 44 02 03 45 46 04 0A 0D will be presented as
“\01ABCD\02\03456\04\0A\0D”
No validation is performed on incoming EIR data.
If a higher signicant ag is set and a lower signicant bit is not set in S 330, for each disabled item
a comma is printed.
Example: S330 = 9 (ADDR enabled, COD and FN disabled, RSSI enabled)
Inquiry Response:
<cr,lf>123456789012,,,-54
<cr,lf>123456789014,,,-54
<cr,lf>OK<cr,lf>
2. AT+BTIV<devclass>{ Inquire }
As per AT+BTI but the response comprises for all inquiry responses:
1. the Bluetooth device address
2. device class code
S register 330 is not referenced.
3. AT+BTIN<devclass> { Inquire }
As per AT+BTI but the response comprises for all inquiry responses:
1. the Bluetooth device address
2. device class code
3. friendly name
S register 330 is not referenced.
4. AT+BTIR<devclass>{ Inquire }
As per AT+BTI but the response comprises for all inquiry responses:
1. the Bluetooth device address
2. device class code
3. friendly name
4. rssi (receiver signal strength indicator)
S register 330 is not referenced.
5. AT+BTIE<devclass> { Inquire }
As per AT+BTI but the response comprises for all inquiry responses:
1. the Bluetooth device address
2. device class code
3. friendly name
4. rssi (receiver signal strength indicator)
5. extended inquiry data
S register 330 is not referenced.
AT COMMAND SET
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6. AT+BTE=”<EIR-Data>”{Set Up Outgoing EIR Data}
This command sets up outgoing EIR (extended inquiry response) data.
Format: <EIR-Data> = printable ASCII character whenever possible, otherwise a two digit hexadecimal
with preceding ‘\’ presenting one byte. Please note that the given data is written to baseband as it
is (raw data) and no checks on the data format is performed. Hence, the user is responsible for writing
data that corresponds to the extended inquiry response data format as described in the Bluetooth
Specication Version 2.1 + EDR [1], vol3, Part C – Generic Access Prole, 8 Extended Inquiry Response
Data Format (page 1305 in the .pdf-le).
Response: <cr,lf>OK<cr,lf>
7. AT+BTE? {Query Outgoing EIR Data}
This command prints the outgoing EIR data that is currently set up
Response:
<cr,lf>
<EIR-Data>
<cr,lf>OK<cr,lf>
Secure Simple Pairing (SSP)
Secure Simple Pairing (SSP) has been introduced since Bluetooth 2.1 + EDR. It aims to increase the security
provided by a Bluetooth link whilst making the pairing process more user friendly.
There are white papers about SSP available through the Internet (provided by the Bluetooth SIG and other com-
panies), explaining the mechanisms and backgrounds of SSP. They can be found by searching the Internet for,
e.g., “Bluetooth Secure Simple Pairing”. Please familiarize with those documents to get a better understanding
of SSP and the following settings.
1. Security Level (S320)
The security level is dened in the BT2.1+EDR specication [1], vol3, Generic Access Prole (Table 5.7).
There are 4 Levels providing different levels of security:
Security Level Characteristics Comment
Level 3 • MITM protection (MITM = “Man in the
Middle” attack)
• Encryption
• User interaction
High security
Level 2 • No MITM protection
• Encryption
Medium Security
Level 1 • No MITM protection
• (No) Encryption (1)
• Minimal user interaction
Low Security
Level 0 • No MITM protection
• No Encryption
• Minimal user interaction
Permitted only for service
discovery
(1) Although encryption is not necessary for security level 1, encryption will always be enabled
because this specication mandates encryption for all services other than SDP (service discovery).
Table 3.3: Security Levels
The security level is dened by S Register 320 and is referenced at boot time only. Hence the register
must be saved by “AT&W “ and the module must be power cycled (or “ATZ”) subsequently.
S320 = 3 will overwrite the setting of S Register 322 (enable MITM).
The security level will remain the same until next power cycle and is valid for all proles and services
of the module. For SDP (service discovery prole), security level 0 is always assigned internally.
AT COMMAND SET
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2. IO-Capability (S321)
S-Register 321 denes the IO-capability of the device. The setting is used for IO-capability negotiations
prior to SSP in order to identify whether the IO-capabilities of both devices are sufcient for MITM
protection (if required). Table 3.4 lists possible values.
S321 IO-Capability Comment
0 Display only The device has the capability to display or communicate a
six digit decimal number.
1 Display yes no The device has the capability to display or communicate
a six digit decimal number and at least two buttons that
can be easily mapped to ‘yes’ and ’no’ or a mechanism
whereby the user can indicate either ‘yes’ or ‘no’ (e.g.,
pressing a button within a certain time limit).
2 Keyboard only The device has a numeric keyboard that can input
numbers ‘0’ through ‘9’ and a conrmation. The device
has also at least two buttons that can be easily mapped
to ‘yes’ and ’no’ or a mechanism whereby the user can
indicate either ‘yes’ or ‘no’ (e.g., pressing a button within
a certain time limit).
3 No input no output The device does not have the ability to indicate ‘yes’ or
‘no’, and the device does not have the ability to display or
communicate a 6 digit decimal number.
4 Reject IO-Cap requests IO-capability requests prior to SSP are rejected.
Table 3.4: IO capabilities
3. Force Man-In-The-Middle Protection (MITM, S322)
Protection against MITM-attacks can be enabled by S332. This S-Register only applies if the security
level (S320) is less than 3. In case of security level (S320) = 3, MITM protection is always enabled and
this S 322 is ignored.
A new value written to S322 applies immediately. No power cycle is required.
A link key created with MITM protection is named “authenticated link key”.
A link key created without MITM protection is named “unauthenticated link key”.
4. Disable Legacy Pairing (S323)
If the remote device is a legacy device (BT2.0 or earlier), legacy pairing with usage of PIN codes will
be initiated. Legacy Pairing can be disabled by S-Register 323 = 1. Then pairing with legacy devices
will always fail.
5. SSP Timeout (S324)
The SSP timeout [s] is dened by S-Register 324. The timeout must be at least 60s to meet the BT
specication requirements [1]. This time is required to be sufcient for the user to compare or read
and input a 6 digit number. A time of 90 seconds is recommended which is the default value.
6. SSP Input Commands
Table 3.5 lists all AT commands related to SSP input operations.
AT Command Operation Comment
AT+BTBY Accept pairing request Representing ‘yes’ input
AT+BTBN Reject pairing request Representing ‘no’ input
AT+BTB012345 Enter six digit passkey displayed by remote device Representing keyboard input
Table 3.5: SSP Input commands
AT COMMAND SET
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