Sonar Sensor Ultrasonic Distance Sensor HC-SR04

HC-SR04 Sensor Features
Operating voltage: +5V
Theoretical Measuring Distance: 2cm to 450cm
Practical Measuring Distance: 2cm to 80cm
Accuracy: 3mm
Measuring angle covered: <15°
Operating Current: <15mA
Operating Frequency: 40Hz
HC-SR04 Ultrasonic Sensor – Working
As shown above, the HC-SR04 Ultrasonic (US) sensor is a 4 pin module, whose pin names are Vcc, Trigger, Echo and Ground respectively. This sensor is a very popular sensor used in many applications where measuring distance or sensing objects are required. The module has two eyes like projects in the front which forms the Ultrasonic transmitter and Receiver. The sensor works with the simple high school formula that

Distance = Speed × Time

How to use the HC-SR04 Ultrasonic Sensor
The HC-SR04 distance sensor is commonly used with both microcontroller and microprocessor platforms like Arduino, ARM, PIC, Raspberry Pie etc. The following guide is universal since it has to be followed irrespective of the type of computational device used.

Power the Sensor using a regulated +5V through the Vcc ad Ground pins of the sensor. The current consumed by the sensor is less than 15mA and hence can be directly powered by the onboard 5V pins (If available). The Trigger and the Echo pins are both I/O pins and hence they can be connected to the I/O pins of the microcontroller. To start the measurement, the trigger pin has to be made high for 10uS and then turned off. This action will trigger an ultrasonic wave at a frequency of 40Hz from the transmitter and the receiver will wait for the wave to return. Once the wave is returned after it getting reflected by any object the Echo pin goes high for a particular amount of time which will be equal to the time taken for the wave to return back to the sensor.

The amount of time during which the Echo pin stays high is measured by the MCU/MPU as it gives information about the time taken for the wave to return back to the Sensor. Using this information the distance is measured as explained in the above heading.

Applications
Used to avoid and detect obstacles with robots like biped robots, obstacle avoider robots, pathfinding robots,s, etc.
Used to measure the distance within a wide range of 2cm to 400cm
Can be used to map the objects surrounding the sensor by rotating it
Depth of certain places like wells, pits etc can be measured since the waves can penetrate through the water