Mobile Phone Bluetooth Control - Keywish Hummer-Bot Instruction Manual

3.2.7 Mobile Phone Bluetooth Control

3.2.7.1 Suite Introduction
Bluetooth is a wireless technology standard that enables short distance data exchange between fixed
devices, mobile devices and building personal domain networks (using 2.4~2.485GHz ISM band UHF radio
waves). Bluetooth technology was originally created by Ericsson in 1994 as an alternative to the RS232 data
cable. It is the best choice of wireless transmission which has been applied to all walks of life now.
Bluetooth module is mainly to realize the data transmission between host computer and slave computer,
there are two kinds of communication methods, one is parallel communication, the other is serial
communication.
Transmitting the data of each unit simultaneously is called parallel communication. Parallel
communication of Arduino relies on parallel I/O. The biggest advantage of parallel communication is the
fast speed of information transmission. The disadvantage is that every bit of the unit information needs a
signal line. Therefore, parallel communication wastes materials.
Transmitting the data of each unit bit by bit is called serial communication. Serial communication can
be realized by serial connection port. The outstanding advantage of serial communication is that only one
pair of transmission lines is needed to transmit information. The disadvantage is that it is slower than
parallel communication.
The design of the data transmission in this section is only for command transmission, the data volume
is not large,so we will use serial communication to realize the wireless communication between host
computer and slave computer, namely MCU serial communication.
Bluetooth module is the most important part of mobile phone Bluetooth control, it has the function of
receiving remote control commands. The selection of Bluetooth module should be based on the design
scheme, there are several hard demands in material selection: the reaction should be sensitive, easy to use,
cost-effective, reliable communication. Through the online information, it is found that HC-05 Bluetooth
module is more suitable for the design requirements, the purchase is also convenient and the effective
distance is wide.
HC-05 Bluetooth wireless communication module has two working modes, one is command response
mode, and the other is automatic connection mode. In the command response mode, the user sends the AT
work instruction to the module to set the control parameters of the module and give the control instructions.
In the automatic connection mode, the module has three working modes, namely the host(Master), the slave
(Slave) and the loop (Loopback) mode. When the work mode is selected, the module will transmit data
automatically according to the setting mode. The working state of the module can be dynamically converted
by adjusting the input level of the external pin of the module. The physical diagram of module is shown in
Fig.3.2.47.
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