| The technique of portability, mass volume of data storage and high precision of A/D conversion is becoming a hot spot in data acquisition field at present. The implementation and application of this technology would solve problems such as low precision, data volatility, that can't be done by traditional data acquisition method.The subject originated from a project of High Precision and Portable Data Acquisition Device of Applied Mechanics Research Institute of TYUT. The subject was to design a portable device with high A/D precision and USB storage which can sample signals from application field.On the dissertation a solution of data acquisition device based on the embedded operation system, mass storage via USB and high precision of A/D conversion was given after massive references was consulted and popular related devices on the market investigated.This device consists of two parts, of which the host can function as data-storage, real-time display of LCD and ambient temperature inspection, communication with upper PC through RS485 interface while acquisition part can implement multi-channel data acquiring, including 6 analog signals and 8 switch signals, data transferring to the host through SPI bus.In the acquisition part, two MSP430F425 microprocessors from TI Company are employed to undertake data acquiring and 16-bit A/D conversion. for the sake of the best A/D conversion linearity of the input, a scale auto-switch circuit was made. The results of acquisition are transferred to the host through SPI bus.The host adopts 32 bits, ARM core LPC2132 as microcontroller, which is produced by PHILIPS Semiconductor Corporation. It has strong data processing ability and abundant resources in chip to meet the needs of data acquisition. In the circuit of data storage, LPC2132 writes data to U disk in the format of FAT16 file system by USB interface chip CH375. PC could have data further analysis and process by reading U disk. Saving data at U disk characterizes the mobility of the device. The LCD interface and keyboard circuit were devised and the schematics shown in detail to ease the observation and operation of customers.The software design of the acquisition part and the host were done to fulfill the device's function. The programs of acquisition part includes A/D conversion, data processing, switch signal collecting and SPI correspondence. The task management of embedded operation system was introduced to the host software design. The transplant ofμC/OS-II to LPC2132 was completed and specific task and code were done to function the device. The adoption ofμC/OS-II optimizes the real-time attribute and convenience the expansion and promotion the system.The system was debugged by the test circuits, which proved the designfeasible and reasonable. The experiment would support the design of highprecision mobile data acquisition device.At the last stage, the dissertation introduced the jobs author did, explainedthe feature and significance. the defects and the improvement was pointed outat the same time. |
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