Based On The Pic18 Family Of Microcontrollers Embedded Real-time Operating System

This thesis mainly introduces a method of designing and implementing an embedded Real-Time Operating System based on PIC18 microcontroller family. PIC18 microcontroller family produced by Microchip Technology Incorporated are used as the hardware platform.Because of the restrictions of the original foreground/background programming, PIC18 microcontroller family face new challenge in application and development.With more c omplicated application, task level response time will be longer, not fixed, and because of inappropriate scheduling of resourses, the problem of deadlock and decrease of system reliability will be more outstanding.In order to resolve these problems and combine its powerful function with our more demands for IT products, we replace the orginal foreground/background programming with Embedded Real-Time Operating System programming.RTOS is a new system design conception and an open software frame.It decreases the complexity of the routine.It has basic functions of an operating system that can control the whole Real-Time system, and it assigns occupation time of CPU and other different resources between tasks according to the importance and urgency of them.It improves the efficiency of CPU usage by providing semaphore, message and other system functions.Besides, the usage of RTOS makes it convenient for the expansion of the application.Since the embedded system tends to combine with Internet and RTOS can manage and support several TCP/IP connections, it is necessary to use RTOS in embedded systems.The design of Embedded RTOS mainly includes the design of kernel structure, task management, time management, task synchronization and communication, the combination with TCP/IP stack and application programming.Finally, we applied our design to the digital remote monitoring system of water pump. We combined the RTOS with the demands of data acquisition, analysis, storage and transmission in water pump monitoring fields and developed an application system.It run successfully and has proved the RTOS we designed had well stability and reliability.By the combination with TCP/IP stack, we realized the embedded Internet based on embedded RTOS.It can be predicted that because of the great advantages of RTOS, it will speed up the development of embedded application enormously and improve the stability, reliability and expansibility greatly.