Review on 📏 Enhance Distance Sensing with Excelity 3pcs Ultrasonic Module HC-SR04 and Mounting Bracket by Drew Gengler

I bought these units to replace a robotic vehicle (Picar-X) that also came with the HC-SR04 sensor. However, none of these devices worked in this application - the Picar-X turned out to supply 3.3V to the HC-SR04, while every HC-SR04 device I encountered operated at 5V. Apparently the creators of Picar -X are using the 3.3V variant or maybe they modified the stock HC-SR04. I then connected each sensor to my raspberry pi (using the Bluetin_Echo library) in turn and found all three devices to be working fine. It's important to note that the pi gpio pins operate at 3.3V while the HC-SR04 operates at 5V, so be sure to include a pull-down resistor on the "echo" output from the HC-SRO4 to the pi gpio pin (the "trigger" input works). good at 3.3V). The HC-SR04 generates a return pulse (at the echo contact) whose width is proportional to the measured distance. Determining the length of this pulse can be problematic since the pulse width is only measured in microseconds. Computers like the Raspberry P, running a relatively complex operating system, are not optimized for high-precision time interval measurements. Therefore, you should expect jitter and occasional false readings. If you need a more accurate and stable sensor, consider devices that return numeric distance values over an RS232 TTL or I2C bus (e.g. HRLV-MaxSonar-EZ1). Okay, the sensor was fine and working fine. Plastic frames are ideal for transponders and are easy to attach. I used a drop of epoxy to attach the sensor to the frame. These devices depend on the speed of sound, which depends on temperature. You should be aware of this limitation common to all (uncompensated) ultrasonic transducers. I typically calibrate and map these devices at various distances (in software) and use a temperature sensor to tune into the prevailing speed of sound. However, these are not super accurate devices. However, they offer excellent value for money and are very effective for simple robotics. For more complex robots I use stereo cameras and lidar - both are not cheap! For Raspberry Pi I used the Bluetin_Echo library to run the HC-SRO4. A simple solution. Overall I think it was a good purchase and I am happy with my customer.