基于msp430单片机的液位测量仪设计毕业论文外文翻译

基于msp430单片机的液位测量仪设计毕业论文外文翻译内容摘要：

baud rate inside, it can make whenever MCU works at any value of crystal oscillator above 32768HZ (but doesn39。 t beyond the upper limit of crystal oscillator), its choice of munication band rate can make band rate factor use decimal without restriction, that is, it can use any frequency value of crystal oscillator in permitted range of band rate. Moreover, MSP430 MCU integrated temperature sensor inside, so it can be realize temperature pensation to pressure sensor used by liquid level measurement conveniently. Further, MSP430 series SCM were made up of different modules against different application and the microcontrollers were designed powered by battery, and it can worked long time. Convert Technology of Analog Signal Because execute unit of system is electromagic valve, it easily to generate electromagic interference, so that the system must has enough anti interference capacity to guarantee reliable work. There are two ways to improve anti interference capacity of system: One way is use A/D converter of MCU directly, that characteristic is it doesn39。 t need peripheral circuits and has faster sampling rate but has worse anti interference capacity. Another way is use V/F converter to realize A/D transformation. Because of V/F converter utilize electrical charge balance principle of integral capacitance to realize voltage to frequency convert, so that this way has better stability, higher resolution, fewer signal wire, easy to realize photoelectric isolate to improve anti interference capacity of system but has slower transformation speed. We consider that pressure signal is a slowly signal, usually needn39。 t rapid sampling. Let system has higher anti interference capacity, choose use V/F converter to realize process to pressure signal through pared and analyzed. This choice has easier calculate and process, can achieve apply requirement in measurement accuracy level, and easier to realize real time control. 3 System General Structures and Principle The whole system is made up of SCM host system, sensor signal processing circuit, liquid control circuit, optic alarm circuit, keyboard, liquid crystal display, power module and munication module etc.. P1 interface act as data bus of system, output signal of V/F convert circuit as interrupt request signal and link to pin of 附录 4 69 SCM, pin and pin act as control signal of execute unit electromagic valve, control input liquid and output liquid electromagic valve separately. Control signal of optic alarm circuit is pin. Keyboard interface circuit linked to SCM to control six keystroke of system through pin, pin and pin. System output signal to 74HC245 for data interface of Chinese character LCD through pin and pin, and pin and pin as control signal of LCD. 和 act as serial munication data bus of SCM, and connected to node across munication circuit to provide serial munication between Master site and。