FBT06 series module is running (STATE) of the three states,
1) transition: the module is in search or waiting to be connected
2) Fixed High (LED lit): has been to establish a connection with the paired modules
3) fixed low (LED not lit): AT mode or shutdown
Note: RS232 interface and the UART interface is used only choose one, you can not use both functions.
Two, EVB and MCU debug connection order
Bluetooth communication with other microcontrollers communicate only need to take three DuPont wire: GND RXD TXD, do not take VCC; Bluetooth chip itself, but would require external power supply of 3.3V VCC, such as with the microcontroller using a different power, make sure that Bluetooth is powered.
Bluetooth module <===> SCM
VCC <===> Bluetooth module power (default from USB 3.3V, also can add other power supply (2.7 ~ 3.6V))
GND <===> GND GND are connected with the microcontroller
TXD <===> MCU-RX microcontroller UART data receive pin
RXD <===> MCU-TX pin microcontroller UART data transmission