Ultrasonic Sensor

• 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 Ultrasonic transmitter transmits an ultrasonic wave, this wave travels in air and when it gets objected by any material it gets reflected back toward the sensor this reflected wave is observed by the Ultrasonic receiver module.
• HC-SR04 distance sensor is commonly used with both microcontroller and microprocessor platforms like Arduino, ARM, PIC, Raspberry Pie etc.
• 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 on board 5V pins (If available). The Trigger and the Echo pins are both I/O pins and hence they can be connected to 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 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 the information about the time taken for the wave to return back to the Sensor.

Applications

• Used to avoid and detect obstacles with robots like biped robot, obstacle avoider robot, path finding robot 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 water