Initializing the hardware before the Linux system starts.
After it is completed, start Linux system for scheduling
their respective mandates. Program flow chart is shown in
figure 4, which mainly includes initializing hardware,
configurating parameters, establishing connection,
transferring data and breaking connection [7].
(1) Initializing hardware.The ARM processor sends out
some AT instructions to control the 4G module to complete
the system startup, initialize the serial port, which includes baud rate, data bits, flow control, etc.