Due to the strong directionality of the ultrasonic wave, the slow energy consumption, and the long distance traveled in the medium, ultrasonic waves are often used to measure the distance. For example, the distance meter and the level measuring instrument can be realized by ultrasonic waves. The use of ultrasonic detection is often more rapid, convenient, simple calculation, easy to do real-time control, and can meet the industrial practical requirements in the measurement accuracy, so it has also been widely used in the development of mobile robots. This article mainly introduces the HC-SR04 ultrasonic distance measuring module and the detailed diagram of the production map. First of all, it introduces the principle and characteristics of ultrasonic distance measurement. Secondly, it describes the HC-SR04 ultrasonic distance measuring module, and finally presents the HC-SR04 ultrasonic ranging module. Make a map, follow the small series together to find out. Ultrasonic distance measurement principle is to send out ultrasonic wave in the ultrasonic launching device. It is based on the time difference when the receiver receives the ultrasonic wave and is similar to the principle of radar distance measurement. The ultrasonic transmitter emits ultrasonic waves in a certain direction and starts timing at the same time as the transmission time. The ultrasonic wave propagates in the air, and immediately returns to the obstacle when it hits an obstacle. The ultrasonic receiver stops immediately after receiving the reflected wave. (The ultrasonic wave propagation speed in the air is 340m/s. According to the time t recorded by the timer, the distance (s) from the obstacle to the obstacle can be calculated, ie, s=340t/2. Features 1, the higher the frequency, the higher the accuracy, but the closer the detection distance (air attenuation increases); 2, the higher the output power, the higher the sensitivity, the farther the detection distance (although it is nonsense, but I must write); 3, usually the detection angle is small, ranging range is slightly far; 1, module features The HC-SR04 ultrasonic ranging module has an accurate ranging distance and is comparable to ultrasonic ranging such as SRF05 and SRF02. The measurement distance is **2cm~450cm (small series: 10cm~300cm). 2, the working principle 1) Use IO trigger ranging to give a high signal for at least 10us. 2) The module automatically sends eight 40KHz square waves and automatically detects if there is a signal return. 3) There is a signal return, a high level is output through the IO, and the duration of the high level is the time from the transmission of the ultrasonic wave to the return time. 3, electrical parameters 4, ultrasonic timing diagram The above timing diagram shows that you only need to provide a pulse trigger signal of more than 10uS. The module will internally send 8 cycles of 40kHz and detect the echo. The echo signal is output as soon as an echo signal is detected. The pulse width of the reverberation signal is proportional to the measured distance. From this, the distance can be calculated by transmitting the signal to the received reverberation time interval. Formula: uS/58=cm or uS/148=inch; or: distance=high time*sound (340M/S)/2; recommended measurement period is 60ms or more to prevent the influence of the transmitted signal on the reverberation signal. Note: 1. This module is not suitable for live connection. For live connection, first connect the GND terminal of the module first, otherwise it will affect the normal operation of the module. 2. When measuring distance, the area of ​​the measured object is not less than 05 square meters and the plane should be as flat as possible, otherwise the result of the measurement will be affected. 5, ultrasonic ranging module internal circuit diagram Nanning Ousibang Information Technology Co., Ltd. , https://www.ousibangvape.com
