Abstract:

We employ the PCA modules of MCU C8051F120 and software simulation to extend a halfduplex serial port in the design of a fermentation controller. We extend multiple 485 bus in one serial port with the chip MAX485, so solve the problem of serial port deficiency. The extended serial port using PCA modules send or receive data in interruption mode of PCA, so it occupies very little CPU time. It can be used as hardware serial ports besides more interruption times. Multiple extended 485 bus from one serial port can connect multiple lower computers with different protocols and different baud rate to complete the sequence communication. Application flexibility is significantly improved, as compared with single 485 bus.

Key words: serial port extension, serial port simulation, multiple 485 bus