Feature: Internal with logic level conversion circuit. No need external 5V level to turn into a 3.3V level The power input port with anti-anti-circuit. To avoid accidental power plug reversed, leading to the module burned HM-10, HM-11 series Bluetooth module using TI CC2540 chip, configuration 256Kb space, support AT commands, you can change the role (master and slave mode) and the baud rate, the device name, Pairing password and other parameters, convenient and flexible.