Bluetooth Module Serial Communication AT command set

Ref: www.linotux.ch/arduino/

HC-05 embedded Bluetooth serial communication module has two work modes: order-response work mode and automatic connection work mode . And there are three work roles (Master, Slave and Loopback) at the automatic connection work mode. When the module is at the automatic connection work mode, it will follow the default way set lastly to transmit the data automatically. When the module is at the order-response work mode, user can send the AT command to the module to set the control parameters and sent control order. The work mode of module can be switched by controlling the module PIN (PIO11) input level.

Serial module PINs:

1. PIO8 connects with LED. When the module is power on, LED will flicker. And the flicker style will indicate which work mode is in using since different mode has different flicker time interval.

2. PIO9 connects with LED. It indicates whether the connection is built or not. When the Bluetooth serial is paired, the LED will be turned on. It means the connection is built successfully.

3. PIO11 is the work mode switch. When this PIN port is input high level, the work mode will become order-response work mode. While this PIN port is input low level or suspended in air, the work mode will become automatic connection work mode. 4. The module can be reset if it is re-powered since there is a reset circuit at the module.


1. How to get to the AT mode?

Method 1:

Step 1: Input low level to PIN34.

Step 2: Supply power to the module.

Step 3: Input high level to the PIN34.

Then the module will enter to AT mode. The baud rate is as same as the communication time, such as 9600 etc.

Method 2:

Step 1: Connect PIN34 to the power supply PIN.

Step 2: Supply power to module (the PIN34 is also supplied with high level since the PIN34 is connected with power supply PIN). Then the module will enter to AT module. But at this time, the baud rate is 38400. In this way, user should change the baud rate at the AT mode, if they forget the communication baud rate.

2. How to get to the communication mode?

Step 1: Input low level to PIN34.

Step 2: Supply power to the module. Then the module will enter to communication mode. It can be used for pairing.

3. How to set this module be the master role ?

Step 1: Input high level to PIO11.

Step 2: Supply power to the module. And the module will enter to the order-response work mode.

Step 3: Set the parameters of the super terminal or the other serial tools (baud rate: 38400, data bit:8, stop bit:1, no parity bit, no Flow Control)

Step 4: Sent the characters “AT+ROLE=1\r\n” through serial, then receive the characters “OK\r\n”. Here, “\r\n” is the CRLF.

Step 5: Input low level to PIO, and supply power to the module again. Then this module will become master role and search the other module (slave role) automatically to build the connection.

Notes.

1. HC-03 and HC-05’s command should end up with “\r\n”. It means when you finish programming, you should add terminator (“ENTER” or “0x0d 0x0a”) to the program. It’s different from HC-04 and HC-06 (They don’t need terminator).

2. The most common commands for HC-03 and HC-05 are: AT+ROLE (set master –slave), AT+CMODE( set address pairing) , AT+PSWD (set password). If you want the master module has the function of remembering slave module, the most simply way is: First, set AT+CMODE=1. Make the master module pair with the slave module. Second, set AT+CMODE=0. Then the master module just can make pair with that specified slave module.

3. When PIN34 keeps high level, all commands can be used. Otherwise, only some of them can be used.


Bluetooth Module AT Commands

(AT command is case- sensitive, should end up with terminator (“enter” or “\r\n”).)

1. Test

Command Response Parameter
AT OK None

2. Reset 

Command Response Parameter
AT+RESET OK None

3. Get the soft version

Command  Response  Parameter
AT+VERSION? +VERSION: <Param> OK Param: Version number

Example :

at+version?\r\n

+VERSION:2.0-20100601

OK

4. Restore default status

Command Response Parameter
AT+ORGL OK None

The parameter of default status:

  1. Device type: 0
  2. Inquire code: 0x009e8b33
  3. Module work mode: Slave Mode
  4. Connection mode: Connect to the Bluetooth device specified
  5. Serial parameter: Baud rate: 38400 bits/s; Stop bit: 1 bit; Parity bit: None.
  6. Passkey: “1234”
  7. Device name: “H-C-2010-06-01”

5. Get module Bluetooth address

Command Response Parameter
AT+ADDR? +ADDR: <Param> OK Param: Bluetooth address

Bluetooth address will show as this way: NAP: UAP: LAP(Hexadecimal)

Example:

Module Bluetooth address: 12: 34: 56: ab: cd: ef

at+addr?\r\n

+ADDR:1234:56:abcdef

OK

6. Set/ inquire device’s name

Command Response Parameter
AT+NAME=<Param> OK
AT+NAME? 1. +NAME:<Param>

OK—-success

2. FAIL—-failure

Param: Bluetooth device name Default: “HC-05”

Example:

AT+NAME=HC-05\r\n                    //set the module device name: “HC-05”

OK

AT+NAME= “HC-05”\r\n      //set the module device name: “HC-05”

OK

at+name=Beijin\r\n            //set the module device name: “Beijin”

OK

at+name= “Beijin”\r\n       //set module device name : “Beijin”

OK

at+name?\r\n

+NAME: Bei jin

OK

7. Get the remote Bluetooth device’s name

Command Response Parameter
AT+RNAME?<Param1> 1. +NAME:<Param1> OK—-success

2. FAIL—-failure

Param1: Remote Bluetooth device address

Param2: Remote Bluetooth device address

Bluetooth address will show as this way: NAP:UAP:LAP (Hexadecimal)

Example:

Bluetooth device address: 00:02:72: od: 22 : 24; device name: Bluetooth

at+rname? 0002,72,od2224\r\n

+RNAME:Bluetooth

OK

8. Set/ inquire module role

Command Response Parameter
AT+ROLE=<Param> OK Param:
0—- Slave role
1—- Master role
2—- Slave-Loop role
Default: 0
AT+ROLE? +ROLE:<Param> OK

Role introduction:

  • Slave (slave role)—-Passive connection;
  • Slave-Loop—-Passive connection, receive the remote Bluetooth master device data and send it back to the master device;
  • Master (master role)—-Inquire the near SPP Bluetooth slave device, build connection with it positively, and build up the transparent data transmission between master and slave device.

9. Set/inquire device type

Command Response Parameter
AT+CLASS=<Param> OK Param: device type
Bluetooth device type is a 32-bit
parameter indicates the device
type and what type can be
supported.
Default: 0
More information is provided at
the appendix 1(device type
introduction).
0—- Slave role
1—- Master role
2—- Slave-Loop role
Default: 0
AT+CLASS? 1. + CLASS:<Param>
OK—-success
2. FAIL—-failure

For inquiring the custom Bluetooth device from around Bluetooth devices quickly and effectively, user can set the module to be non-standard Bluetooth device type, such as 0x1f1f (Hexadecimal).

10. Set/ inquire-Inquire access code

Command Response Parameter
AT+IAC=<Param> 1. OK—-success
2. FAIL—-failure
Param: Inquire access code
Default: 9e8b33
The more information is provided at the
appendix 2(Inquire access code introduction).
AT+IAC? +IAC: <Param>
OK

Access code is set to be GIAC type (General Inquire Access Code:0x9e8b33), and used for seeking ( or being sought by ) all the Bluetooth devices around. For inquiring (or being inquiring by) the custom Bluetooth device from around Bluetooth devices quickly and effectively, user can set the inquire access code to be the other type number (not GIAC nor LIAC), such as 9e8b3f.

Example:

AT+IAC=9e8b3f\r\n OK AT+IAC?\r\n

+IAC: 9e8b3f

OK

11. Set/ inquire – Inquire access mode

Command Response Parameter
AT+INQM=<Param>,
<Param2>,<Param3>
1. OK—-success
2. FAIL—-failure
Param: Inquire access mode
0—-inquiry_mode_standard
1—-inquiry_mode_rssi
Param2: the maximum of Bluetooth
devices response
Param3:The maximum of limited
inquiring time
The range of limited time: 1~48
( Corresponding time:1.28s~61.44s)
Default: 1, 1, 48
AT+ INQM? +INQM:<Param>,<Param2>,<P
aram3>
OK

Example:

AT+INQM=1,9,48\r\n    //Set Inquire access mode: 1) has RSSI signal intensity indicator, 2) stop inquiring once more than 9 devices response, 3) limited time is 48*l. 28=61.44s.

OK

AT+INQM\r\n

+INQM:1, 9, 48

OK

12. Set/Inquire- passkey

Command Response Parameter
AT+PSWD=<Param> OK Param: passkey
Default: “1234”
AT+PSWD? +PSWD : OK

13.Set/ Inquire- serial parameter

Command Response Parameter
AT+UART=<Param>,<
Param2>,<Param3>
OK Param1: baud rate( bits/s)
The value (Decimal) should
be one of the following:
4800
9600
19200
38400
57600
115200
23400
460800
921600
1382400
Param2:stop bit:
0—-1 bit
1—-2 bits
Param3: parity bit
0—-None
1—-Odd parity
2—-Even parity
Default: 9600, 0, 0
AT+UART? +UART=<Param>,<Para
m2>,<Param3>
OK

Example:

Set baud rate to be 115200, stop bit to be 2 bits, parity bit to be even parity. AT+UART=115200,1,2,\r\n

OK

AT+UART?

+UART:115200,1,2

OK

14. Set/ Inquire – connection mode

Command Response Parameter
AT+CMODE=<Param> OK Param:
0—-connect the module to the
specified Bluetooth address.
(Bluetooth address can be
specified by the binding
command)
1—-connect the module to any
address
(The specifying address has no
effect for this mode.)
2—-Slave-Loop
Default connection mode: 0
AT+ CMODE?  +CMODE:<Param>
OK

15. Set/Inquire – bind Bluetooth address

Bluetooth address will show as this way: NAP: UAP:LAP(Hexadecimal)

Command Response Parameter
AT+BIND=<Param> OK Param—-Bluetooth address
needed to be bind
Default address:
00:00:00:00:00:00
AT+BIND?  +BIND:<Param>
OK

This command is effective only when the module wants to connect to the specified Bluetooth address. Example: The module is at connection mode which connects to specified Bluetooth address, and the specified address is 12:34:56:ab:cd:ef. Command and the response show as follow:

AT+BIND=1234, 56, abcdef\r\n

OK

AT+BIND?\r\n

+BIND:1234:56:abcdef

OK

16. Set/Inquire – drive indication of LED and connection status

Command Response Parameter
AT+POLAR=<Param1>,
<Param1>
OK Param1:The value is
0—-PI08 outputs low level and turn on
LED
1—-PI08 outputs high level and turn on
LED
Param2:The value is
0—-PI09 output low level, indicate
successful connection
1—-PI09 output high level, and
indicate successful connection
Default: 1, 1
AT+POLAR?  +POLAR=<Param1>,
<Param1>
OK

HC-05 Bluetooth module definition: The output of PI08 drives indication of LED work mode; the output of PI09 indicates the connection status.

Example:

PI08 outputs low level and turn on LED, PI09 outputs high level and indicates successful connection. Command and response show as follow:

AT+POLAR=0, 1\r\n

OK

AT+POLAR?\r\n

+POLAR=0, 1

OK

17. Set PIO single port output

Command Response Parameter
AT+PIO=<Param1>,<Param2> OK Param1: PIO port number(Decimal) Param2: PIO port status

0—-low level

1—-high level

HC-05 Bluetooth module provides the user with the ports (PI00~PI07 and PI010) which can extern another input and output ports.

Example:

1. PI010 port outputs high level

AT+PI0=10, 1\r\n

OK

2. PI010 port outpust low level

AT+PI0=10, 0\r\n

OK

18. Set PIO multiple port output

Command Response Parameter
AT+MPIO=<Param> OK Param: Mask combination of
PIO ports number (Decimal)

HC-05 Bluetooth module provides the ports (PI00~PI07 and PI010) which can extern another input and output ports to the user.

1. Mask of PIO port number = (1<<port number)

2. Mask combination of PIO ports number= (PIO port number mask 1 | PIO port number mask 2 | ….)

Example :

PI02 port number mask=(1<<2) =0x004

PI010 port number mask =(1<<10)=0x400

Mask combination of PI02 and PI010 port number=(0x004|0x400)=0x404

Example:

1. PI010 and PI02 ports output high level

AT+MPI0=404\r\n

OK

2. PI04 port output high level

AT+PI0=004\r\n

OK

3. PI010 port output high level

AT+PI0=400\r\n

OK

4. All ports output low level

AT+MPI0=0\r\n

OK

19. Inquire PIO port input

Command Response Parameter
AT+MPIO? +MPIO: <Param>
OK
Param—-PIO port value (16bits)
Param[0]=PI00
Param[1]=PI01
Param[2]=PI02
……
Param[10]=PI010
Param[11]=PI011

HC-05 Bluetooth module provides the user with the ports (PI00~PI07 and PI010) which can extern another input and output ports.

20. Set/ Inquire page scan and inquire scan parameter

Command Response Parameter
AT+IPSCAN=<Param1>,
<Param2>,
<Param3>,<Param4>AT+I
PSCAN?
OK
+IPSCAN:
<Param1>,<Param2>,
<Param3>,<Param4>
OK
Param1:time interval of
inquiring
Param2: duration in inquiring
Param3: time interval of paging
Param4: duration in paging
The above parameters are
decimal.
Default:1024,512,1024,512

Example:

at+ipscan=1234,500,1200,250\r\n

OK

at+ipscan?

+IPSCAN:1234,500,1200,250

21. Set/ Inquire—SHIFF energy parameter

Command Response Parameter
AT+SNIFF=<Param1>
,<Param2>,
<Param3>,<Param4>
OK Param1: maximum time
Param2: minimum time
Param3: test time
Param4: limited time
The above parameters are decimal.
Default : 0,0,0,0
AT+IPSCAN? +SNIFF:
<Param1>,<Param2>,<Par
am3>,<Param4>

22. Set/ Inquire safe and encryption mode

Command Response Parameter
AT+SENM=<Param
>,<Param2>,
1. OK—-success 2. FAIL—-failure Param: the value of safe mode:
0—-sec_mode0+off
1—-sec_mode1+non_secure
2—-sec_mode2_service
3—-sec_mode3_link
4—-sec_mode_unknown
Param2: the value of encryption mode:
0—-hci_enc_mode_off
1—-hci_enc_mode_pt_to_pt
2—-hci_enc_mode_pt_to_pt_and_bcast
Default: 0,0
AT+ SENM? +SENM:<Param>,<Param
2>,
OK

23. Delete authenticated device in the Bluetooth pair list

Command Response Parameter
AT+PMSAD=<Param> OK Param: Bluetooth device address

Example:

Delete the device ( address: 12:34:56:ab:cd:ef ) in the blue pair list at+rmsad=1234,56,abcdef\r\n

OK    //successful deletion Or

at+rmsad=1234,56,abcdef\r\n

FAIL  //There is no the Bluetooth device whose address is 12:34:56:ab:cd:ef in the pair list.

24. Delete all authenticated devices in the pair list

Command Response Parameter
AT+RMAAD OK None

Example: Move all devices away from the pair list.

at+rmaad\r\n

OK

25. Seek the authenticated device in the Bluetooth pair list

Command Response Parameter
AT+FSAD=<Param> 1. OK—-success
2. FAIL—-failure
Param: Bluetooth device address

Example: Seek the authenticated device (address: 12:34:56:ab:cd:ef) in the pair list at+fsad=1234,56,abcdef\r\n

OK //the Bluetooth device whose address is 12:34:56:ab:cd:ef is found.

at+fsad=1234,56,abcde0\r\n

FAIL   //There is no the Bluetooth device whose address is 12:34:56:ab:cd:e0 in the pair list.

26. Get the authenticated device count from the pair list

Command Response Parameter
AT+ADCN? +ADCN:<Param>
OK
Param: Authenticated Device
Count

Example:

at+adcn?

+ADCN:0 //There is no authenticated device in the pair list.

OK

27. Get the Bluetooth address of Most Recently Used Authenticated Device

Command Response Parameter
AT+MRAD? +MRAD : <Param>
OK
Param: the Bluetooth address of
Most Recently Used
Authenticated Device

Example:

at+mrad?

+MRAD:0:0:0   //There is no device that has been used recently.

OK

28. Get the work status of Bluetooth module

Command Response Parameter
AT+STATE?  +STATE: <Param>
OK
Param: work status of module
Return value:
“INITIALIZED” —-initialized status
“READY” —- ready status
“PAIRABLE” —-pairable status
“PAIRED” —-paired status
“INQUIRING” —-inquiring status
“CONNECTING”—-connecting status
“CONNECTED”—-connected status
“DISCONNECTED”—-disconnected
status
“NUKNOW”—-unknown status

Example:

at+state?

+STATE:INITIALIZED    //initialized status

OK

29. Initialize the SPP profile lib

Command Response Parameter
AT+INIT 1. OK—-success
2. FAIL—-failure
None

30. Inquire Bluetooth device

Command Response Parameter
AT+INQ +INQ: <Param1>,<Param2>,<Param3>,
……
OK
Param1: Bluetooth address
Param2: device type
Param3: RSSI signal
intensity

Example 1:

at+init\r\n    //Initialize the SPP profile lib( can’t repeat initialization)

OK

at+iac=9e8b33\r\n    //Inquire Bluetooth device has an access code

OK

at+class=0\r\n    //Inquire the Bluetooth device type

at+inqm=1,9,48\r\n   //Inquire mode: 1) has the RSSI signal intensity indication, 2) stop inquiring if more than 9 Bluetooth devices response, 3) limited time in inquiring is 48*1.28=61.44s.

at+inq\r\n    //inquire the Bluetooth device around

+INQ:2:72:D2224,3E0104,FFBC

+INQ:1234:56:0,1F1F,FFC1

+INQ:1234:56:0,1F1F,FFC0

+INQ:1234:56:0,1F1F,FFC1

+INQ:2:72:D2224,3F0104,FFAD

+INQ:1234:56:0,1F1F,FFBE

+INQ:1234:56:0,1F1F,FFC2

+INQ:1234:56:0,1F1F,FFBE

+INQ:2:72:D2224,3F0104,FFBC

OK

Example 2:

at+iac=9e8b33\r\n   //inquire the Bluetooth device has an access code

OK

at+class=1f1f\r\n    //inquire the Bluetooth device whose device type is 0x1f1f

OK

at+inqm=1,9,48\r\n    //inquire mode: 1) has the RSSI signal intensity indication, 2) stop inquiring if more than 9 Bluetooth devices response, 3) limited time in inquiring is 48*1.28=61.44s

at+inq\r\n      //filter and inquire the Bluetooth device around

+INQ:1234:56:0,1F1F,FFC2

+INQ:1234:56:0,1F1F,FFC1

+INQ:1234:56:0,1F1F,FFC1

+INQ:1234:56:0,1F1F,FFC1

+INQ:1234:56:0,1F1F,FFC2

+INQ:1234:56:0,1F1F,FFC1

+INQ:1234:56:0,1F1F,FFC1

+INQ:1234:56:0,1F1F,FFC0

+INQ:1234:56:0,1F1F,FFC2

OK

Example 3:

at+iac=9e8b3f\r\n     //inquire the Bluetooth device whose access code is 0x9e8b3f

OK

at+class=1f1f\r\n       //inquire the Bluetooth device whose device type is 0x1f1f

OK

at+inqm=1,1,20\r\n     //inquire mode: 1) Has the RSSI signal intensity indication, 2) stop inquiring if more than 1 Bluetooth device response, 3) limited time in inquiring is 20*1.28=25.6s

at+inq\r\n    //filter and inquire the Bluetooth device around

+INQ:1234:56:ABCDEF,1F1F,FFC2

OK

31. Cancel Bluetooth device

Command Response Parameter
AT+INQC OK None

32. Set pair

Command Response Parameter
AT+PAIR=<Param1>,<Param2> 1. OK—-success
2. FAIL—-failure
Param1: Bluetooth address of
remote device
Param2: limited time of
connection (second)

Example: Make pair with the remote Bluetooth device( address:12:34:56:ab:cd:ef), the limited time is 20s.

at+pai=1234,56,abcdef,20\r\n

OK

33. Connect device

Command Response Parameter
AT+LINK=<Param> 1. OK—-success
2. FAIL—-failure
Param: Bluetooth address of
remote device

Example: Connect with the remote Bluetooth device (address: 12:34:56:ab:cd:ef)

at+fsad=1234,56,abcdef\r\n      //To check whether the Bluetooth device (address: 12:34:56:ab:cd:ef) is in the pair list or not.

OK

at+link=1234,56,abcdef\r\n        //The Bluetooth device (address: 12:34:56:ab:cd:ef) is in the pair list. The connection can be built directly without inquiring.

OK

34. Disconnection

Command Response Parameter
AT+DISC 1.+DISC:SUCCESS—-successful Disconnection
OK
2.+DISC:LINK_LOSS—-lose the connection
OK
3.+DISC:NO_SLC—-No SLC connection
OK
4、+DISC:TIMEOUT—-disconnection timeout
OK
5、+DISC:ERROR—-disconnection error
OK
None

35. Enter to energy mode

Command Response Parameter
AT+ENSNIFF=<Param> OK Param: Bluetooth address of device

36. Exit energy mode

Command Response Parameter
AT+EXSNIFF=<Param> OK Param: Bluetooth address of device

Appendix 1:Introduction of AT command error code

The form of error —- ERROR:(error_code)

error_code(Hexadecimal) Note
0 AT command error
1 Default result
2 PSKEY write error
3 Too long length of device name (more than 32 bytes).
4 No device name
5 Bluetooth address: NAP is too long.
6 Bluetooth address: UAP is too long.
7 Bluetooth address: LAP is too long.
8 No PIO number’s mask
9 No PIO number
A No Bluetooth devices.
B Too length of devices
C No inquire access code
D Too long length of inquire access code
E Invalid inquire access code
F The length of passkey is 0.
10 Too long length of passkey (more than 16 bytes)
11 Invalid module role
12 Invalid baud rate
13 Invalid stop bit
14 Invalid parity bit
15 Authentication device is not at the pair list.
16 SPP lib hasn’t been initialized.
17 SPP lib has been repeated initialization.
18 Invalid inquire mode
19 Too long inquire time
1A No Bluetooth address
1B Invalid safe mode
1C Invalid encryption mode

Appendix 2: The introduction of devices

The Class of Device/Service(CoD) is a 32 bits number that of 3 field specifies the service supported by the device. Another field specifies the minor device class, which describes the device type in more detail.

The Class of Device /Service (CoD) field has a variable format. The format is indicated using the ’within the CoD .The length of the Format Type field is variable and ends with two bits different from’11’.The version field starts at the least significant bit of the CoD and may extend upwards. In the ’format#1’ of the CoD (format Type field =00), 11 bits are assigned as a bit –mask (multiple bits can be set) each bit corresponding to a high level generic category of service class. Currently 7 categories are defined. These are primarily of a’ public service’ nature. The remaining 11 bits are used for indicating device type category and other device-specific characteristics. Any reserved but otherwise unassigned bits, such as in the Major Service Class field, should be to 0.

1. MAJOR SERVICE CLASSES

Bit no Major Service Class

  • 13 Limited Discoverable Mode
  • 14 (reserved)
  • 15 (reserved)
  • 16 Positioning(Location identification)
  • 17 Networking (LAN, Ad hoc, … )
  • 18 Rendering (Printing ,Speaker,…)
  • 19 Capturing (Scanner, Microphone,…)
  • 20 0bject Transfer (v-Inbox, v-Folder,…)
  • 21 Audio (Speaker, Microphone, Headset service,…)
  • 22 Telephony (Cordless telephony, Modem, Headset service,…)
  • 23 Information (WEB-server, WAP- server,…)

2. MAJOR DEVICE CLASSES

The Major Class segment is the highest level of granularity for defining a Bluetooth Device. The main function of a device is used for determining the major Class grouping. There are 32 different possible major classes.

  • 0 0 0 0 0 Miscel laneous  
  • 0 0 0 0 1 Computer (desktop, notebook, PDA, organizers,…)
  • 0 0 0 1 0 Phone (cellular ,cordless ,payphone, modem,…)
  • 0 0 0 1 1 LAN/Network Access point 0 0 1 0 0 Audio/Video (headset, speaker, stereo, video display, vcr …)
  • 0 0 1 0 1 Periphereal (mouse, joystick, keyboards.…)
  • 0 0 1 1 0 Imaging (printing, scanner, camera, display,…)
  • 1 1 1 1 1 Uncategorized, specific device code not specified
  • X X X X All other values reserved

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