Bluetooth serial module is used for
converting serial port to Bluetooth. These modules have two modes: master and
slaver device. The device named after even number is defined to be master or
slaver when out of factory and can’t be changed to the other mode. But for the
device named after odd number, users can set the work mode (master or slaver)
of the device by AT commands.
When HC-05 is out of factory, one part of
parameters is set for activating the device. The work mode is not set, since
user can set the mode of HC-05 as they want.
The main function of Bluetooth serial module is replacing the serial
port line, such as:
1.
There are two MCUs want to communicate with each other. One connects to
Bluetooth master device while the other one connects to slave device. Their
connection can be built once the pair is made. This Bluetooth connection is
equivalently liked to a serial port line connection including RXD, TXD signals
and they can use the Bluetooth serial module to communicate with each other.
2.
When MCU has Bluetooth slave module, it can communicate with Bluetooth
adapter of computers and smart phones. Then there is a virtual communicable
serial port line between MCU and computer or smart phone.
3.
The Bluetooth devices in the market mostly are slave devices, such as
Bluetooth printer, Bluetooth GPS. So, we can use master module to make pair and
communicate with them. Bluetooth Serial module’s operation doesn’t need drive,
and can communicate with the other Bluetooth device which has the serial.
But communication between two Bluetooth
modules requires at least two conditions:
Ø
The communication must be between master and slave.
Ø
The password must be correct.
