User Manual

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As shown in the above figure, HC-12 module is used in physical wiring when

replacing half duplex communication. The left device sends serial port data to module,

and after RXD port of left module receives the serial port data, it will automatically

send the data into the air via radio wave. The right module can automatically receive

the data, and restore, from TXD, the serial port data originally sent by the left device.

It is the same from right to left. Only half duplex state is available between modules,

and they cannot receive and send data at the same time.

(2) Serial port transparent transmission

HC-12 module has three serial port transparent transmission modes, expressed with

FU1, FU2 and FU3 respectively. In the use, all modes are only responsible for

receiving and sending serial port data rather than wireless transmission. The default

working mode of system is in FU3 full-speed mode, and in this mode, the baud rate in

this air can be automatically adjusted according to baud rate of serial port, and the

communication distance will be the farthest at the low baud rate. Different modes

cannot transmit data to each other, and user could select the optimal mode according

to practical circumstances.

The modules are usually used in pairs, and transmit data by means of half duplex.

Meanwhile, the transparent transmission mode, serial port baud rate, and wireless

communication channel of two paired modules shall be set to be the same. The default

setting is FU3, 9,600bps (8-dibit data, no check, one stop bit), CH001 (433.4MHz).

Use the number of bytes continuously sent to serial port of module unlimited to one

time. However, considering ambient interference and other factors, if thousands of

data size is sent continuously at a time, some number of bytes may be lost. Therefore,

the upper computer shall have response and resending mechanism, to avoid

information loss.

(3) Three serial port transparent transmission modes

When HC-12 module leaves the factory, its default serial port transparent transmission

mode is FU3. Then the module is in full-speed state, and the idle current is about

MCU, PC and other device

Wired

MCU, PC and other device

Module replaces wire and becomes wireless

communication

Half-duplex

HC-12 module