Pc104 Motherboard-based Embedded Data Acquisition System Developed

This dissertation is based on the design and implementation of a high speed data acquisition system with PC/104 system and real-time operating system QNX.The difficulty of implementing such a system lies in that the data must be saved to disk ASAP while the data acquisition is in process and the whole system have to be placed in a very small space. As a result, the data acquisition system must be an embedded real time system.In this dissertation the concept of the embedded real-time system was first introduced, then its development processes, current circumstances and future perspectives were analyzed, and at the end, the design idea of adopting PC/104 system as the hardware platform and adopting QNX as the software platform was presented.PC/104 is a dedicated industrial control bus for embedded control system. PC/104 motherboard and its relative devices constitute the small stack-based embedded control system which is applied in all kinds of fields extensively for its small size, high performance, reliability and wide temperature range. DM5408 data acquisition card was used in the system. The hardware structures and interface features such as data sample, FIFO, DMA, interrupt of DM5408 were studied in detail in order to achieve the best real time performance.The real time multi-task operating system-QNX, as adopted in the system, ensures that the high speed data acquisition system is real time and reliable. The Windows NT is compared with QNX on architecture and real-time performance in this article, and thus the conclusion that QNX is necessary and significant in the system can be obtained.QNX system has a special implementation mechanism for device drivers. Based on the deep analysis of the core of device drivers, namely, the structure, composition, type and characters of Resource Manager, the corresponding device driver was programmed and whole software was implemented.It is proved by practice that the data acquisition system has a good real time characteristic, correctness and reliability.