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论文编号:ZD1271 论文字数:22562,页数:62 附原理图,外文翻译
摘要:
本设计以AT89C51单片机为核心,采用两线制实现了煤矿瓦斯报警系统,系统定时采样矿井下的瓦斯浓度,将此浓度值经MT8888双音频芯片转换成DTMF音频信号传输到地面的上位机。同时在井下用LED显示器显示矿井下瓦斯浓度,当瓦斯浓度超过报警限度值时报警,此外,系统还设置了四按键键盘来修改报警限度值和采样周期。
系统首先采用开关电源器件L4960将18伏电源转换成所需要的5伏和3伏电源,其中3伏电源信号送给传感器黑白件,为其供电。5伏电源则作为其它器件的电源。黑白件将瓦斯浓度转换成电压信号并送入运算放大器LM358进行放大,此模拟电压信号再传给V/F转换器件LM331,通过它将模拟电压信号转换成频率信号。AT89C51单片机将这一数字信号送入MT8888芯片转换成DTMF信号传输给上位机。同时AT89C51将频率信号转换成便于井下工人识读的0~4分的浓度值送LED显示。系统采用X5043来存储报警值和采样周期,并通过四位键盘分别控制他们,若超限则通过声光报警系统报警。
本设计的软件部分主要有主程序和完成浓度测量,输出频率,LED显示,键盘查询等功能的模块组成。
关键词:两线制 煤矿瓦斯 频压转换 键盘显示
Summary
The design completes a two-line mine gas alarm system which uses the single chip computer AT89C51 as the core. The system collects the density of gas at fixed time, and transmits it to the computer on the ground through the chip MT8888. As the same time, the system displays the density by the LED displayer under the mine. When the density of the gas exceeds the alarm figure, the system will give alarm. Besides, I place 4keys in the system to change the alarm figure and the fixed time.
Firstly the system transimits the 18-voltage power supply into 5-voltage and 3-voltage power source. The 3-voltage power source is the supply of the gas sensitive element the black and white. And the 5-voltage is the power sources of the other electronic devices. The black and white thansimts the density of the gas into the voltage signal and passes it to the amplifier LM358. The analogue signal is then passed to the V/F transformer LM331, which translate voltage signal into frequency signal. AT89C51 passes the digital signal to the MT8888 chip, which transmits the signal to the up-ground computer through the DTMF signal. Besides, the AT89C51 changes the frequency signal into density signal of 0~4 fen, which is convenient to the miners. When the density of the gas exceeds the alarm figure, the system will shine and raise warning sound. There are 4 keys to change alarm figure and the fixed time which are stored in the x5043.
The soft part of the design includes the main programme and the blocks such as the density, collect, the frequency export, the LED display and the keys search.
Keywords:Two lines system Coal mine gas The frequency converts with the electric voltage Keyboard manifestation
目录
概述…………………………………………………………(1)
设计方案论证………………………………………………(2)
硬件部分……………………………………………………(3)
3.1电源…………………………………………………………(3)
3.2信号采集……………………………………………………(6)
3.3频压转换……………………………………………………(7)
3.4放大电路……………………………………………………(10)
3.5 AT89C51单片机……………………………………………(11)
3.6 MT8888芯片…………………………………………………(20)
3.7看门狗电路…………………………………………………(25)
3.8报警系统和输出频率………………………………………(31)
3.9显示与按键…………………………………………………(32)
四.软件部分………………………………………………………(33)
4.1 X5043发送接收程序………………………………………(33)
4.2 MT8888初始化及数据发送程序…………………………(33)
4.3 键盘程序……………………………………………………(34)
4.4 程序框图……………………………………………………(34)
4.5 程序清单……………………………………………………(36)
结束语………………………………………………………………(60)
参考文献……………………………………………………………(61)
附:两线制煤矿瓦斯报警仪电路原理图。