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HC-05 Bluetooth AT Command List

May 4, 20188 mins read
Arduino Bluetooth Module

The HC-05 is a common Bluetooth module used in many microcontroller projects. Here's a compilation of all HC-05 Bluetooth AT Commands. For beginners, see Arduino Bluetooth.

Setting HC-05 to AT Command Mode

By default, the HC-05 is configured in data mode. In this mode, the module acts like a serial bridge. To put into AT command mode the KEY pin must be set (high).

However, there are modules where the KEY pin is missing or is not wired to the actual KEY pin of the IC. To solve this, wire pin 34 of the IC to 3.3 V:

Modified HC-05 Module

The HC-05 is now in command mode if the red LED flashes once every two seconds.

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The following commands require that the HC-05 is connected to the Arduino as a serial device. Below is an example wiring diagram and sketch/code:

Arduino to HC-05 connection for AT Commands

#include <SoftwareSerial.h>

SoftwareSerial Bluetooth(7,8);

void setup() {
  Serial.begin(9600);
  Bluetooth.begin(9600);
}

void loop() {
  while (Serial.available()) {
      delay(1);
      Bluetooth.write(Serial.read());
  }
  while (Bluetooth.available()) {
       Serial.write(Bluetooth.read());
  }
}

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Test command

Command Response Parameter
AT OK -

 

Reset

Command Response Parameter
AT+RESET OK -

 

Get firmware version

Command Response Parameter
AT+VERSION? +VERSION:<Param>

OK

 Param : firmware version

Example:

AT+VERSION?
+VERSION:2.0-20100601
OK

 

Restore default

Command Response Parameter
AT+ORGL OK -

Default state:

Slave mode, pin code :1234, device name: H-C-2010-06-01 ,Baud 38400bits/s.

Get module address

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

Bluetooth address: NAP: UAP : LAP

Example:

AT+ADDR?
+ADDR:1234:56:abcdef
OK

 

Set/Check module name:

Command Response Parameter
AT+NAME=<Param> OK Param: Bluetooth module name (Default :HC-05)
AT+NAME? +NAME:<Param>

OK

or

FAIL

Example:

AT+NAME=HC-05      ;set the module name to “HC-05”
OK 
AT+NAME?
+NAME: HC-05
OK

 

Get the Bluetooth device name:

Command Response Parameter
AT+RNAME?<Param1> +NAME:<Param2>

OK

or

FAIL

 Param1,Param 2 : the address of Bluetooth device

Example: (Device address 00:02:72:od:22:24，name：HC-05)

AT+RNAME? 0002，72，od2224
+RNAME:HC-05
OK

 

Set/Check module mode:

Command Response Parameter
AT+ROLE=<Param> OK 0 - Slave

1 - Master

2 - Slave-Loop
AT+ ROLE? +ROLE:<Param>

OK

 

Set/Check device class

Command Response Parameter
AT+CLASS=<Param> OK Param: Device Class
AT+CLASS? +CLASS:<Param>

OK

or

FAIL

 

Set/Check GIAC (General Inquire Access Code)

Command Response Parameter
AT+IAC=<Param> OK

or

FAIL

 Param: GIAC (Default : 9e8b33)
AT+IAC +IAC:<Param>

OK

Example:

AT+IAC=9e8b3f
OK
AT+IAC?
+IAC: 9e8b3f
OK

 

Set/Check -- Query access patterns

Command Response Parameter
AT+INQM=<Param>,<Param2>,

<Param3>

 OK

or

FAIL

 Param:

0 -- inquiry_mode_standard

1 -- inquiry_mode_rssi Param2: Maximum number of Bluetooth devices to respond to

Param3:

Timeout (1-48 : 1.28s to 61.44s)
AT+ INQM? +INQM ：<Param>,<Param2>,

<Param3>

OK

Example:

AT+INQM=1,9,48
OK
AT+INQM
+INQM:1, 9, 48
OK

 

Set/Check PIN code:

Command Response Parameter
AT+PSWD=<Param> OK Param: PIN code

(Default 1234)
AT+PSWD? + PSWD : <Param>

OK

 

Set/Check serial parameter:

Command Response Parameter
AT+UART=<Param>,<Param2>,< Param3> OK Param1: Baud

Param2: Stop bit

Param3: Parity
+UART=<Param>,<Param2>,

<Param3>

OK

Example:

AT+UART=115200,1,2,
OK
AT+UART?
+UART:115200,1,2
OK

 

Set/Check connect mode:

Command Response Parameter
AT+CMODE=<Param> OK Param:

0 - connect fixed address

1 - connect any address

2 - slave-Loop
+ CMODE:<Param>

OK

 

Set/Check fixed address:

Command Response Parameter
AT+BIND=<Param> OK Param: Fixed address

(Default

00:00:00:00:00:00)
AT+BIND? + BIND:<Param>

OK

  

 

Example:

AT+BIND=1234,56,abcdef
OK
AT+BIND?
+BIND:1234:56:abcdef
OK

 

Set/Check LED I/O

Command Response Parameter
AT+POLAR=<Param1,<Param2> OK Param1:

0- PIO8 low drive LED

1- PIO8 high drive LED

Param2:

0- PIO9 low drive LED

1- PIO9 high drive LED
+ POLAR=<Param1>,<Param2>

OK

 

Set PIO output

Command Response Parameter
AT+PIO=<Param1>,<Param2> OK Param1: PIO number

Param2: PIO level

0- low

1- high

Example:

;PIO10 output high level
AT+PI0=10,1
OK

 

Set/Check – scan parameter

Command Response Parameter
AT+IPSCAN=<Param1>,<Param2

>,<Param3>,<Param4>

 OK Param1: Query time interval

Param2: Query duration

Param3: Paging interval

Param4: Call duration
AT+IPSCAN? +IPSCAN:<Param1>,<Param2>,<Param3>,<Param4>
OK

Example:

AT+IPSCAN =1234,500,1200,250
OK 
AT+IPSCAN?
+IPSCAN:1234,500,1200,250

 

Set/Check – SNIFF parameter

Command Response Parameter
AT+SNIFF=<Param1>,<Param2>,

<Param3>,<Param4>

 OK Param1: Max time

Param2: Min time

Param3: Retry time

Param4: Time out
AT+SNIFF? +SNIFF:<Param1>,<Param2>,<Param3>,<Param4>

OK

 

Set/Check security mode

Command Response Parameter
AT+SENM=<Param1>,<Param2> OK

or

FAIL

 Param1:

0 --sec_mode0+off

AT+ SENM? + SENM:<Param1>,<Param2> 1——sec_mode1+non_secure

2 -- sec_mode2_service

3 -- sec_mode3_link

4 -- sec_mode_unknown

Param2:

0 -- hci_enc_mode_off

1 -- hci_enc_mode_pt_to_pt

2 -- hci_enc_mode_pt_to_pt_and_bcast

 

Delete Authenticated Device

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

Authenticated Device Address

Example:

AT+PMSAD =1234,56,abcdef
OK

 

Delete All Authenticated Device

Command Response Parameter
AT+ RMAAD OK

 

Search Authenticated Device

Command Response Parameter
AT+FSAD=<Param> OK

or

FAIL

 Param: Device address

 

Get Authenticated Device Count

Command Response Parameter
AT+ADCN? +ADCN：<Param>

OK

 Param: Device Count

 

Most Recently Used Authenticated Device

Command Respond Parameter
AT+MRAD? + MRAD：<Param>

OK

 Param: Recently Authenticated Device Address

 

Get the module working state

Command Response Parameter
AT+ STATE? + STATE：<Param>

OK

 Param:

“INITIALIZED”

“READY”

“PAIRABLE”

“PAIRED”

“INQUIRING”

“CONNECTING” “CONNECTED”

“DISCONNECTED”

“NUKNOW”

 

Initialize the SPP profile lib

Command Response Parameter
AT+INIT OK

or

FAIL

 -

 

Inquiry Bluetooth Device

Command Response Parameter
AT+INQ +INQ: <Param1>， <Param2>， <Param3>

….

OK

 Param1：Address

Param2：Device Class

Param3：RSSI Signal strength

Example:

AT+INIT 
OK
AT+IAC=9e8b33
OK 
AT+CLASS=0
AT+INQM=1,9,48
AT+INQ
+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

 

Cancel Inquiring Bluetooth Device

Command Response Parameter
AT+ INQC OK -

 

Equipment Matching

Command Response Parameter
AT+PAIR=<Param1>,<Param2> OK

or

FAIL

 Param1：Device Address

Param2：Time out

 

Connect Device

Command Response Parameter
AT+LINK=<Param> OK

or

FAIL

 Param：Device Address

Example:

AT+FSAD=1234,56,abcdef
OK 
AT+LINK=1234,56,abcdef 
OK

 

Disconnect

Command Response Parameter
AT+DISC +DISC:SUCCESS

OK

or

+DISC:LINK_LOSS

OK

or

+DISC:NO_SLC

OK

or

+DISC:TIMEOUT

OK

or

+DISC:ERROR

OK

 Param：Device Address

 

Energy-saving mode

Command Response Parameter
AT+ENSNIFF=<Param> OK Param：Device Address

 

Exerts Energy-saving mode

Command Response Parameter
AT+ EXSNIFF =<Param> OK Param：Device Address

 

Pairing Two HC-05 Modules

Use an FTDI USB to Serial converter to configure the bluetooth module once it’s in command mode (how to set in command mode). Then use Arduino’s serial monitor to send out commands. The default baud rate for command mode is 38400. One module is the master device while the other is the slave device. Pairing configuration is done through the master device.

Step 1: Check if the HC-05 master is in command mode:

AT 
> OK

Step 2: Reset the configurations to their default values:

AT+ORGL
> OK

Step 3: Set the module to master:

AT+ROLE=1 
> OK

Step 4: Reset the module:

AT+RESET 
> OK

Step 5: Wait, then initialize:

AT+INIT 
> OK

Step 6:  Forget all the previous connections:

AT+RMAAD 
> OK

Step 7: Determine MAC address of slave device. Set slave device to command mode and issue command:

AT+INQ 
> +INQ:98D3:31:FC20A9,1F00,7FFF

Here, it shows that the slave device has a MAC address of 98D3:31:FC20A9. The 1F00 is the device class while the 7FFF is the received signal strength indicator (RSSI).

Step 8: Back to master module; pair with the slave device:

AT+PAIR=98D3,31,FC20A9,20 
> OK

After pairing, the LED on the master module will start flashing with about two seconds of pause.

Step 9: Bind the master and slave devices:

AT+BIND=98D3,31,FC20A9 
> OK

Step 10: Link the two devices:

AT+LINK=98D3,31,FC20A9 
> OK

If successful, both the master and slave device's LED will now blink twice followed by about two seconds of pause.

Roland Pelayo started TMM in 2015. He is a firmware engineer who has over ten years of experience in developing electronic and microcontroller-based systems. Roland's designs include medical devices, security and automation, robots, emergency alert systems, and educational training modules.   Have something that you like Roland to write about here? or do you need consultation for microcontroller firmware projects? just contact him via the contact page.

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