HC-05 Bluetooth Module

Description

Serial port bluetooth, Drop-in replacement for wired serial connections, transparent usage. You can use it simply for a serial port replacement to establish connection between MCU and GPS, PC to your embedded project and etc. 
Application

• Computer and peripheral devices
• GPS receiver
• Industrial control
• MCU projects

 

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1.1 tips (very important):
the TXD: Send side, generally expressed as their own sender, normal communication must be connected to another device RXD. 
RXD: the receiver, generally designated himself on the receiving end, normal communication TXD must be connected to another device. 
When normal communication itself TXD RXD always connected device! 
Since the resumption of spontaneous: RXD when normal communication TXD connected to other devices, so if you want to receive data sent by itself as the name suggests, is to receive the data they transmit their own, that is directly connected to its own TXD RXD, used to send and receive test itself It is normal, is the quickest and easiest way to test when there is a problem to do the first test to determine if product failure . Also known as the loopback test.

1.2 level logic:
TTL level: usually binary data representation, provisions equivalent to + 5V logic "1", 0V is equivalent to a logical "0", the system is called TTL signal is positive logic 
RS232 level: using -12V to -3V is equivalent to a logic "0", + 3V with + 12V to logic level equivalent to logic "1", a negative logic

1.3 Product Features:
1, the core module uses HC-05 from the module, leads to interface includes VCC, GND, TXD, RXD, KEY pin, Bluetooth connection status pinout (STATE), low output is not connected, the connection of high output
2, led indicates Bluetooth connection status, flash means no Bluetooth connectivity, slow flash that enter the AT mode, double flash indicates Bluetooth is connected and turned on port
3, the floor set anti-reverse diode with 3.3V LDO, input voltage 3.6 ~ 6V, when unpaired current is about 30mA, paired about 10mA, the input voltage must not exceed 7V! 
4, interface level 3.3V, can be directly connected to various SCM (51, AVR, PIC, ARM , MSP430 , etc.), 5V microcontroller can also be connected directly, without MAX232 can not go through MAX232! 
5, clearing the effective distance of 10 meters ( power rating of cLASS 2), more than 10 meters is possible, but not from the quality of this connection to do to ensure 
6, after the pair when full-duplex serial port to use, without having to know any Bluetooth protocol, supports 8 data bits, 1 stop bit , you can set the parity communication format, which is the most common communication format does not support other formats. 
7, can be pulled 34 feet into the AT command mode setting parameters and query information 
8, small size (3.57cm * 1.52cm), factory chip production to ensure the quality of the patch.Transparent shrink tube and sleeve, dust and beautiful, and there is a certain anti-static capabilities. 
9, can be selected via AT command as master or slave mode, can be connected via AT command specifies the device 
10, supported from the standard baud rates between 4800bps ~ 1382400bps

1.4 Usage:
After pairing only as a fixed baud rate of the serial port can be used in the same, so long as it is "fixed baud, 8 data bits, no parity" communication format serial devices can be directly replace the original wired serial port without the need to modify the program. Such as data acquisition, smart car, serial printers, and other outdoor dot matrix screen control. Paired with a computer: for inter-computer with a Bluetooth device via serial communications, use the same serial port with the phone paired with: suitable between your phone with a Bluetooth device via serial communication, use the serial port as a Bluetooth host paired: for two devices directly through the Bluetooth serial communication, such as between the microcontroller and microcontroller serial cable with microchips, etc., use the same serial port

Workaround Use:
baud rate conversion, because the receiver and the sender can choose their own baud rate, in a small amount of data when you can use the device as a baud rate of transformation.

2.1 How Bluetooth module connected to your computer (slave mode effective)
    the following order with the computer with Bluetooth paired with an example: 
First, to pass through the Bluetooth module power, this time led flashes, open "My bluetooth location", click "Search for equipment "within the effective range,

The system will search for Bluetooth devices, the default device name "linvor" (as modified name was modified name, such as "jiayuanelectron"), double-click or right-click to select "Add Bluetooth Device"

Enter a passcode (default is "1234"),

Click "Next", if the password is correct, the computer and transparent transmission module will establish a connection, if not previously had a Bluetooth serial devices installed, the system will automatically install the driver and generate a virtual serial port

Click Configuration, select the appropriate COM port,

Here I can only choose com5, the serial port is connected to the computer after the end of the operation, such as I have here is com5, open the port when the Bluetooth module by the LED willflash into a double flash , then just take the Bluetooth module as it is the computer's serial port to use a fixed baud rate of the same, except that it is wireless.

Documents:

• HC-05 AT Command
• Simple instructable to connect the module to Arduino
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