The fingerprint SOC can form complete fingerprint identification module with several necessary periphery circuit sensor, flash, power supply, etc.. The module is in Slave mode all the time. The host can issue different instructions to the module, for various functions. The host instruction, modules ACK and data exchanges are all work according to given format data packet. The host should packet instructions and data which need transmitting as well as analyze received data packets based-on the following format. For multi-byte data, the high byte is in front, low byte retro.