HC-05 Bluetooth Transmission Module for Arduino
Bluetooth transmission module can enable you to get rid of using cable for a serial port device and realize wireless serial communication within 10 meters. Using the module doesn't require knowing the complex bluetooth bottom protocol. A few simple steps can get you to enjoy the convenience of wireless communication.
Bluetooth transmission module has only 4 AT command. Respectively are communication testing, name changing, baud rate changing, matching password changing. AT command must be set from TXD, RXD signal pins, not via bluetooth channel. Device sending the AT command can be various types of MCU (for example, 51, avr, PIC, msp430, arm, etc.). It can also be a computer sending via serial port (PC serial port connected to MAX232 or USB serial port).
Core module use HC-05 slave module, interfaces include VCC, GND, TXD, RXD, KEY, bluetooth state pin (STATE), output low if not connected, high if connected.
LED indicates the connection status of bluetooth, quick flash means no connectivity, slow flash means entering AT mode, double flash means bluetooth is connected.