Features: The module uses core module, leading out to interfaces include VCC, GND, TXD, RXD, KEY, bluetooth connection state (STATE), output low when not connected, and output high after connection. LED indicates bluetooth connection state, fast flash means no bluetooth connection, slow flash means entering AT mode, double flash means bluetooth connection and open port. Designed with diode for reverse input protection, with 3.3V LDO; input voltage is 3.6~6V; unpaired current is about 30mA, and paired current is about 10mA; input voltage should not be higher than 7V! Interface level 3.3V, can be connected directly to a variety of single chip microcomputers, 5V microcontroller can also be connected directly. The effective distance in an open filed is about 10 meters, power level is CLASS 2. After pairing, it can be used as full duplex serial port, do not need to know any bluetooth protocol, support 8 bits of data, 1 bits of stop, can be set as odd-even check communication format, which is the most commonly used communication format, does not support other formats. Can pull up 34 pin up to enter AT command mode for setting parameters and query information. Can switch to host or slave mode, and connect to specified equipment through AT command. Support standard baud rate between 4800bps and 1382400bps. Specifications: Input Voltage: 3.6~6V Effective Distance: About 10 meters (in open field) Size: 4.5*1.8cm/1.8*0.7in Weight: 3g(approx.) Package Includes: 1 x Bluetooth Module 1、The module uses core module, leading out to interfaces include VCC, GND, TXD, RXD, KEY, bluetooth connection state (STATE), output low when not connected, and output high after connection. 2、LED indicates bluetooth connection state, fast flash means no bluetooth connection, slow flash means entering AT mode, double flash means bluetooth connection and open port. 3、Designed with diode for reverse input protection, with 3.3V LDO; input voltage is 3.6~6V; unpaired current is about 30mA, and paired current is about 10mA; input voltage should not be higher than 7V! 4、Interface level 3.3V, can be connected directly to a variety of single chip microcomputers, 5V microcontroller can also be connected directly. 5、The effective distance in an open filed is about 10 meters, power level is CLASS 2.