| Since the thermal insulation property of building envelope has intimate relations with its energy saving performance, it is essential to have field detection before delivery. The moisture content is an important parameter which has an influence on thermal performance. So it will provide important parameters for thermal insulation property of building envelope, by accurately measuring the moisture content distribution in depth direction of wall.In this paper, based on the properties of building envelope, we taked the planar capacitive sensor as the testing component of the moisture content. The planar capacitive sensor, which overcomes the shortcomings of traditional mathod in moisture content checking, so as to detect in a larger scale. Meanwhile, we has been realized the detection of moisture along the direction of depth of the wall, with the chromatography algorithm, and we could infer the relationship between the output voltage and the moisture content.To facilitate the processing of capacity, we designed the C/V transform and signal conditioning circuit. This circuit, having the smaller capacity, high accuracy, and high anti-jamming property, which convert the capacity to voltage that is proportional to the capacity. In order to design a portable instrument, LPC2210 which belonged to the series of PHIPLIS's ARM7TDMI embedded chip was adopted as key controlled CPU. Then we designed the little system, the conversion circuit of A/D, the serial communication circuit, and the keyboard interfaces circuit. In addition,for the purpose of improving the mutual performance between human and machine, the LCD function was extended to the system.On the aspect of software, this paper uses open-source embedded operating systemμC/OS-II as a software platform, achieves the transplant fromμC/OS-II to LPC2210. Besides, taking ADS1.2 as the development kit , we programed the data processing task, data collecting task, communication task, keyboard task and display task. By the management ofμC/OS-II , tasks coordinates with each other. Finally, we finished the functions of data collecting, processing and displaying. Besides, this paper employed smoothing filter algorithm to enhance the apparatus'ant-jamming capability, and to make the data more reliable. |
