Embedded Systems Development Based On C8051F040 MCU

Embedded systems are special computer system. They are based on computer technology and take the application as the first important thing, their software and hardware can be cut out, and they also fit for application systems which have strict request with function, reliability, cost, power waste and bulk. As the very important basic equipment, Programmable Logic Controller (PLC) is called one of the three major pillars in Automation Industry. In the thesis, under the developed project "Embedded systems development based on C8051F040 MCU", and on the base of studying embedded systems technology, the paper presents design plan for the small PLC. The hardware is based on the high efficient 8 bit embedded microprocessor C8051F040, its input and output function is extended with its plenty of source on chip. The embedded PLC core programme is taken as the center, and the needed application is developed, and is extended to a full and applied PLC system. In the thesis, the PLC core hardware circuit which is based on the microcontroller C8051F040 is deeply studied, including external RAM for power dropping, hardware watchdog circuit and the interface circuit for extent. At the same time, The PLC core software is studied, including its basic function, its structure and realization, its task administration and schedule. Then the power supply of PLC is studied and analyzed, and the power suitable for the small PLC is designed combined the up-to-date SMPS (Switching Mode Power Supply) technology. Base on the singal chip SMPS TOP224Y in the TOPSwitch-II serial of American company Power Integrations Inc., the design method and step of SMPS, and how to select components is presented, basides the performance of SMPS tested. The PLC hardware including the input/output and the communication is studied, and the hardware circuit for the small PLC is designed. The PLC software under the PLC core is designed. At last the PLC system combining an application of PLC is tested, and its performance is evaluated by PLC network extent.