TXD: serial port, 3.3V TTL level.
RXD: serial receiver, 3.3V TTL level.
CTS: serial flow control is not supported.
RTS: serial flow control is not supported.
DC: simulation, burn the clock pin.
DD: simulation, data burning feet.
RST: Reset pin module requires low level of not less than 5ms be reset.
VCC: module power pins require 3.3V DC power supply current is not less than 100mA.
GND: Module common ground.
LED: module indicator output pin, high output, when connected in series with a resistor LED.
Host unrecorded machine address from light per 100ms;
When the machine address from the host record, bright 900ms per second;
Slave bright one second every two seconds.
After connection, LED lit.
KEY: input pin, internal pull-down. The feet high, clear the record for the host address from the machine.
PIO: extension, used to set the module master-slave mode, the default internal pull-up resistor from the machine; 1K external pull-down resistor connected to the ground, as the host.
Currently only supports 9600bps communication, does not support the AT commands. Host, when the machine passthrough traffic from, there must be a certain time interval between packets. For example, the packet length is 500 bytes, then the transmission time interval between packets can be set to no less than 600ms. Otherwise, you might lose data.