【正文】 system. With AT89C2051 single chip processor as the core, for the system to work, teach according to the ultrasonic sensors, the control core to quickly calculate the vehicle to the rear of the distance and obstacles, and through the LED display to remind information, this system mainly using single chip microputer realtime control and data processing functions, plete control of the system. Finally expounds the hardware circuit principle and software design of the alarm. Generally by the ultrasonic sensor (monly known as probe), controller and display parts, under the control of the controller, the device on the rear bumper send ultrasonic probe, encountered obstacles, produce echo signal, the sensor receives the echo signal from the controller for data processing, determine the position of the obstacles, the display shows distance and issued a warning signal, get timely warning, made back more easily. This scheme adopts the voice prompt, this paper introduces the SPCE061A as the core of a low cost, high precision, miniaturization, and has the function of digital display and sound and light alarm, reversing radar system. Using the SPCE061A single chip has voice function, external three ultrasonic ranging module, to form a sample reversing radar system, voice alarm ( m ~ m) within the scope of the obstacles. Keyword AT89C2051 ultrasonic sensor 安徽工貿(mào)職業(yè)技術(shù)學(xué)院畢業(yè)設(shè)計（論文） III 目 錄 引 言 ............................................................................................................................. 1 第一章 方案選擇與分析 ................................................................................................. 2 實現(xiàn)功能 .............................................................................................................. 2 系統(tǒng)總體方案介紹 ................................................................................................ 3 第二章 系統(tǒng)硬件設(shè)計 ..................................................................................................... 4 SPCE061芯片特性 ................................................................................................. 4 SPCE061簡介 ............................................................................................... 4 芯片特性 ...................................................................................................... 5 電源模塊 .............................................................................................................. 5 放音模塊 .............................................................................................................. 6 超聲波測距模組 .................................................................................................... 7 超聲波諧振頻率發(fā)生電路，調(diào)理電路 ............................................................ 7 超聲波 回波接受處理電路 .............................................................................. 8 超聲波測距模組電源接口 .............................................................................. 8 超聲波測距模式選擇跳線 .............................................................................. 8 轉(zhuǎn)接板 .................................................................................................................. 9 轉(zhuǎn)接板電路 ................................................................................................... 9 顯示電路 .................................................................................................... 10 第三章 系統(tǒng)軟件設(shè)計 ................................................................................................... 11 軟件結(jié)構(gòu) ............................................................................................................ 11 超聲波測距原理 .................................................................................................. 11 各模塊程序說明 .................................................................................................. 13 超聲波測距程序 .......................................................................................... 13 語音播放程序 ............................................................................................. 15 顯示刷新程序 ............................................................................................. 17 主程序 .................