Application And Research Of Embedded System And PLD In Traffic Signal Machine

In order to adapt the city intelligent transportation development trend, enhance the technological level of traffic management and road traffic capacity, A intelligent traffic signal machine has been designed by embedded system and programme logic device, included a back circuit and four function circuits (CPU circuit, power circuit, lights phase drive circuit, vehicle detector circuit).Traffic signal machine has been made up of embedded computer PC104 and programme logic device as the core of control circuit.PC104 main has completed system control, data management, traffic analysis, traffic forecasts.At the same time it has downloaded the manual intervention programmes and reported traffic situation information to the central control server and regional control server through the TCP/IP protocol. PC104 has been subjected to the overall coordination and management. PC104 has completed the decision-making programme implementation and controled traffic lights junction switch in term of actual traffic situation.MCU main has completed data collection, data analysis, data communication. These information has been sent to the microcontroller count unit through signal adjust circuit and switching circuit.MCU has analysed information in count and has sent Real-time traffic information to the control circuit through the parallel bus.Programme logic device main has completed PC104 ISA bus expansion, back and cross fun- ctional logic, address decoding logic, control bus logic, data bus driver, hardware watch- dog, RS 232 serial communication expansion and so on.Embedded CPU-PC104 has been taken as dominative controller of traffic signal machine, it has made machine can run complex traffic control algorithms, friendly and interactive human-machine interface because of rich hardware resources, large-capacity storage, high-speed processing capacity, user-friendly operating system. At the same time programme logic device has been used to complete the bus expansion, system fuctions expansion and improve the stability of the system beacause of high integration, low power consumption, high reliability and reconfiguration.