Communication module sorting (II) hc-05

HC-05 Bluetooth module

Module introduction

HC-05 Module is a high-performance master-slave Bluetooth serial port module , It can be paired with a variety of intelligent terminals （ Including all kinds of computers with Bluetooth function 、 Bluetooth Host 、 mobile phone 、PDA、PSP etc. ）. This module supports multiple baud rates , And compatible 5V or 3.3V Single chip system , It is flexible and convenient to use .

How to connect

Module export 6 A word , In actual use, connect VCC、GND、RXD、TXD Just four wires ：
STATE
RXD—— Single chip microcomputer TX
TXD—— Single chip microcomputer RX
GND——GND
VCC——5V
EN

debugging

HC-05 The Bluetooth serial communication module has two working modes ： Command response working mode and automatic connection working mode . In the automatic connection working mode, the module can be divided into main （Master）、 from （Slave） And loop （Loopback） Three job roles .
When the module is in the auto connect operating mode , The data transmission that will be automatically connected according to the preset mode ;
When the module is in command response mode, it can execute AT command , The user can send various messages to the module AT Instructions , Set control parameters or issue control commands for the module .

Enter the command response working mode

Connect the module with USB-TTL Well connected , Open the serial debugging assistant
There are two debugging methods ：
1、 Press and hold the button on the module and power on , Put the module into debugging mode , At this time, the baud rate is fixed to 38400
2、 Send when pressing and holding the key AT command , Only one sentence can be sent at a time , You can modify the configuration parameters under the baud rate at work , The baud rate in working state defaults to 9600
It is recommended to use the first debugging method , In addition, pay attention to ,AT There must be \r\n

Instruction name	Command response	Instruction meaning
AT	OK	Test instruction
AT+RESET	OK	Module reset
AT+VERSION	+VERSION: OK	Get the software version number
AT+ORGL	OK	Restore default state
AT+ADDR?	+ADDR: OK	Get the Bluetooth module address
AT+NAME=BLUETOOTH	OK	Set the device name
AT+PSWD=“1234”	OK	Get the module password
AT+UART=115200,0,0	OK	Set serial port parameters
AT+ROLE=	OK	Select the working mode
AT+RMAAD	OK	Clear the pairing list
AT+CMODE=	OK	To configure A、B Connection mode
AT+BIND=	OK	Bind Bluetooth B Address

among , There are three parameters of serial port , Baud rate 、 Stop bit 、 Inspection position . Its value is as follows ：

Parameter name	Value
Baud rate	2400、4800、9600、19200、38400、5760、115200、230400、460800、921600、1382400
Stop bit	0：1 position 1：2 position
Check bit	0：NONE 1：Odd 2：Even

Working mode of Bluetooth module

AT+ROLE Instructions are used to select HC05 The role of Bluetooth module , There are three roles in total ：

The role type	Configuration instructions	explain
master	AT+ROLE=0\r\n	Set as slave , Only passive connection
slave	AT+ROLE=1\r\n	Set to host , You can query the surrounding SPP Bluetooth slave , And actively connect
loop-slave	AT+ROLE=2\r\n	Set to loopback mode , Passive connection , Receive the host data and return the data as it is

These instructions are used in different situations , When setting the Bluetooth module as a slave , You can connect the device with the relevant Bluetooth serial port software of the mobile phone , To communicate ; When set as the main character , You can search the surrounding Bluetooth slaves , And connect , This mode is commonly used in applications ; Loopback mode is often used for testing .

Communicate with mobile phones

1. Bluetooth module and USB-TTL Conversion module connection , Press and hold the key and connect to the computer , Enter the command response working mode
2. Open the serial debugging assistant , Set the baud rate of the serial port 38400, Open the serial port , Check send new line
3. send out AT+VERSION Return version number , Confirm that the connection is successful
4. send out AT+ORGL, Reply to default settings
5. send out AT+NAME=HC05 , The configuration module name is HC05
6. send out AT+PSWD=“1234” , The configuration module password is 1234
7. send out AT+UART=115200,0,0 Set serial port parameters
8. send out AT+RESET, Change baud rate 115200（ Or power on again ）
9. Turn on the Bluetooth debugging assistant , Search and connect modules , Send messages to each other

STM32 Communicate with mobile phones through modules

After the configuration is completed, receive USART or UART Pin , It can be used as an ordinary serial port

Transparent transmission between modules

1. Prepare two pieces HC-05 Bluetooth module （ The following is called BT-M and BT-S）
2. BT-M and BT-S Respective and USB-TTL Conversion module connection , Connect to the computer and enter the command response working mode
3. Open two serial port debugging assistants , Set the baud rate of the serial port 38400, Open the serial port , Check send new line
4. send out AT+VERSION Return version number , Confirm that the connection is successful
5. send out AT+ORGL, Reply to default settings
6. send out AT+ADDR, Get the device address and record
7. BT-M Address 12：14：1442;BT-S Address 12：14：1443
8. Send separately AT+NAME=BT-M and AT+NAME=BT-S , Configuration module name
9. send out AT+PSWD=“1234” , The configuration module password is the same
10. send out AT+UART=115200,0,0 Set serial port parameters （ Can be different ）
11. send out AT+ROLE=1,BT-M Select host mode ; send out AT+ROLE=0,BT-S Select slave mode
12. send out AT+RMAAD, Clear the pairing list
13. send out AT+CMODE=0, To configure BT-M、BT-S Bluetooth connection mode is any address connection mode
14. Bind Bluetooth address ：AT+BIND=12,14,1443;AT+BIND=12,14,1442（ Change colon to comma ）
15. send out AT+RESET, Change baud rate 115200（ Or power on again ）
16. Wait for the module to match successfully , You can send messages to each other