This is the CP2102(6-pin) USB 2.0 to TTL UART serial converter module. This is a great little tool for embedded systems that require a serial connection to a computer. The board can simply attach to a USB bus and will appear as a standard COM port.
ThisCP2102 doesn’t require any external oscillator, it onboard-board voltage regulator, and it even uses a reprogrammable internal EEPROM for the device description. The full hardware UART has flow control for baud rates from 300bps to 921600bps.