The core module uses the -06 slave module, the outgoing interface includes VCC, GND, TXD, RXD, and the LED status output pin is reserved. The microcontroller can judge whether the Bluetooth has been connected through the status of this pin, and the KEY pin is invalid for the slave machine.LED indicates bluetooth connection status, flashing means no bluetooth connection, steady light means bluetooth is connected and the port is open.The bottom plate is 3.3V LDO, the input voltage is 3.6~6V, the current is about 30mA when not paired, and about 10mA after pairing, and the input voltage is prohibited to exceed 7V The interface level is 3.3V, which can be directly connected to various microcontrollers (51, AVR, PIC, ARM, MSP430, etc.), and 5V microcontrollers can also be directly connected, without MAX232 or through MAX232 The effective distance in the open space is 10 meters, and it is possible to exceed 10 meters, but the connection quality of this distance is not guaranteed.After pairing, it can be used as a full-duplex serial port without knowing any bluetooth protocol, but it only supports the communication format of 8 data bits, 1 stop bit, and no parity check, which is also a commonly used communication format and does not support other formats.When the Bluetooth connection is not established, the baud rate, name, and pairing password can be set through AT commands, and the set parameters can be saved after power off. Automatically switch to transparent transmission mode after bluetooth connection.Small size (3.57cmx1.52cm), factory patch production to ensure patch quality. And set the transparent heat-shrinkable tube, dust-proof and beautiful, and has a certain anti-static ability.This link is a slave machine. The slave function can be paired with various computers with Bluetooth function, Bluetooth hosts, most of the mobile phones with Bluetooth, PDA, PSP and oth.Colour: blueMaterial: PCBPackage Contents:1 * Slave Bluetooth ModuleOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.