Multi-serial-port system based on SPI interconnection

Personal computer only has 1 or 2 serial ports,which causes inconvenience when multiple serial devices are required to communicate with the computer at the same time.Aiming at this problem,a new method of serial port expansion based on SPI had been proposed.The multi-serial-port system which used the new method only took a serial or USB port available,and can connect three or more serial devices.The main body of this system consisted of multiple single chip processors STC12C5410AD which had both UART and SPI.Those processors in this system communicated insingle master-more slaves mode,and the master exchanged the information and data with the slave by SPI.Every slave chip can connect to a serial device,and the master chip connected with the host computer's serial port.Thus,the data can be transferred from computer to serial devices or reverse through this multi-serial-port system.The master and the slave have some data buffers,and the data throughput of master is larger than that of all of the slaves.In addition,and the protocol of data exchange,memory organization,and the software structure are also described in this article.