【正文】 ropagation velocity of 340m / s, according to the timer records the time t, we can calculate the distance between the launch distance barrier (s), that is: s = 340t / 2 Ranging System for the Second Circuit Design System is characterized by singlechip microputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, singlechip selection of 8751, economictouse, and the chip has 4K of ROM, to facilitate programming. Circuit schematic diagram shown in Figure 1. Figure 1 circuit principle diagram 40 kHz ultrasonic pulse generated with the launch Ranging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40, its operating voltage of the pulse signal is 40kHz, which by the singlechip implementation of the following procedures to generate. puzel: mov 14h, 12h。s lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core. Control System is the core ponent of the development of ultrasonic range finder. Therefore, it is very important to design a good ultrasonic range finder. 2. A principle of ultrasonic distance measurement The principle of piezoelectric ultrasonic generator When it39。s standard of living, speeding up the development and construction of the city. urban drainage system have greatly developed their situation is constantly improving. However, due to historical reasons many unpredictable factors in the synthesis of her time, the city drainage system. In particular drainage system often lags behind urban construction. Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon. It brought to the city sewage, and it is clear to the city sewage and drainage culvert in the sewage treatment system. fort is very important to people39。s nature, size and distance from the sensor. Further, the time interval from the echo39。 nop。 related external interrupt 1 jnb , right。 right location entrance circuit interrupt service routine Ajmp Return left: ...。 calculate the time difference MOV 31H, A。為了進一步提高測距的精確度，滿足工程人員對測量精度、測距量程和測距儀使用的要求，本文研制了一套基于單片機的便攜式超聲測距系統(tǒng)。城市污水給人們帶來了困擾，因此箱涵的排污疏通對大城市給排水系統(tǒng)污水處理，人們生活舒適顯得非常重要。 超聲波測距原理 壓電式超聲波發(fā)生器實際上是利用壓電晶體的諧振來工作的。 測量脈沖到達時間的傳統(tǒng)方法是以擁有固定參數的接收信號開端為基礎的。結果，一種錯誤便出現了 —— 兩個擁有不同強度的脈沖在不同時間超過界限卻在同一時間到達。電路原理圖如圖 1所示。 接收頭采用與發(fā)射頭配對的 UCM40R，將超聲波調制脈沖變?yōu)榻蛔冸妷盒盘枺涍\算放大器 IC1A和 IC1B兩極放大后加至 IC2。當收到超聲波反射波時，接收電路 輸出端產生一個負跳變，在 INT0或 INT1端產生一個中斷請求信號，單片機響應外部中斷請求，執(zhí)行外部中斷服務子程序，讀取時間差，計算距離。 第三步：檢測兩種回波的振幅與過零時間。 第五步：發(fā)射兩串脈沖產生干擾波。 超聲波測距系統(tǒng)的軟件設計 軟件分為兩部分，主程序和中斷服務程序?？梢娀趩纹瑱C設計的超聲波測距系統(tǒng)具有硬件結構簡單、工作可靠、測量誤差小等特