HC-SR04 Ultrasound Sensor 4-Arduino

Ultra Simple Test Experiment —Ardu_Serie Episode #81

Looking up how to use this sensor without delay?

Yeap, I admit this example is more than bare-bones in that it sends to serial the measurements data, but this lets you test it without any problems.

Fig 1. a awesome cheap sensor :D

Here is the

code

And here is the

Fritz Schema

Fig 2. Fritzing Simple Schematicto run the code above:)

And the

Lab

Fig 3. The lab. Hey, sorry for the serial inverted ”/

Here are some notes:

- This sensor is very popular among the Arduino tinkerers;
- The module is about 45x20x15 mm in size and has a 4 pin connection;
- There’s an Arduino library called NewPing that can make your life easier when using this sensor;
- The ultrasonic sensor uses sonar to determine the distance to an object;
- The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object like bats do;
- The HC-SR04 sends a ping as a submarine does and measure the time between sending and receiving anything back when an object is in front of the sensor;
- It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package;
- The HC-SR04 uses sound instead of light as the GP2D12 module does;
- HC-SR04 is cheaper than the GP2D12;
- Because using sound for its measurements we can reach up to 4 meters;
- specifications:
Power Supply :+5V DC
Quiescent Current : <2mA
Working Current: 15mA
Effectual Angle: <15°
Ranging Distance : 2cm – 400 cm/1? – 13ft
Resolution : 0.3 cm
Measuring Angle: 30 degree
Trigger Input Pulse width: 10uS
Dimension: 45mm x 20mm x 15mm
- The time between the transmission and reception of the signal allows us to calculate the distance to an object;
- How it Works 1: The transmitter (trig pin) sends a signal: a high-frequency sound. When the signal finds an object, it is reflected and…… the transmitter (echo pin) receives it;
- One ping of the HC0SR04 actually exists of 8 pulses at 40 kHz to do the measurement;
- How it works 2 - One ping of the HC0SR04 actually exists of 8 pulses at 40 kHz to do the measurement; To start a ping you need to provide a 10us pulse on the trigger input; When the distance is measured by the 8 pulses the HC0SR04 puts a pulse on the echo pin. 
You can calculate the distance with the length of the echo pulse and the speed of sound; The speed of sound is 340 m/s or 2.9 micro seconds per mm; We have to divide the length of the pulse by 2.9 to get the result in mm; The ping is traveling towards an object and back to the sensor again; Because of this we need to divide the result by two; Between two pings we need to keep a 60ms measurement cycle;
- NOTE: If the HC-SR04 does not receive an echo then the output never goes low; Devantec and Parallax sensors time out after 36ms and I think 28ms respectively; If you use Pulsin then with no return echo the program will hang for 1 second which is the default timeout for Pulsin. You need to use the timeout parameter;
- If you put a resistor, say 2k2 between E and T then only connect to T you can use the HC-SR04 from just one Arduino pin. Look up single pin operation of ultrasonic sensors;
- Also if you are using a HC-SR04 with a PicAxe you need to up the clockspeed to at least 8MHz otherwise they don’t see the start of the echo pulse so pulsin never starts. The HC-SR04 works fine with a BS2 -  by David Buckley:)

And There you have it!

Not much to say about this sensor. The internet is floated with revision about this awesome and simple to use a sensor device.

Be tuned!

Bye!

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Fig 4. The box, rule and Pibot HC-SR04 Ultra-Sound Sensor.

Credits & References

Ultrasonic Sensor HC-SR04 and Arduino Tutorial by https://howtomechatronics.com

HC-SR04 Ultrasonic Sensor by https://www.botshop.co.za

Lily∞Bot: Obstacle Avoidance With 4 Sonar (HC-SR04)