HC-SR04 Ultrasonic Sensor with Arduino

HC-SR04 Ultrasonic Sensor with Arduino

• The HC-SR04 is an ultrasonic sensor that measures distances between 2 cm and 400 cm.
• It uses sonar principles to measure distance by sending sound waves and calculating the time taken for the echo to return.
• The sensor has a trigger pin that sends an ultrasonic pulse (8 cycles at 40 kHz), and an echo pin that receives the reflected pulse.
• The Arduino calculates the distance using the time of travel and the speed of sound (343 m/s or 0.0343 cm/µs).

Sensor Specifications

• Operating Voltage: 5V DC
• Operating Current: 15 mA
• Operating Frequency: 40 kHz
• Minimum Range: 2 cm / 1 inch
• Maximum Range: 400 cm / 13 feet
• Accuracy: 3 mm
• Measuring Angle: <15°
• Dimension: 45 x 20 x 15 mm

Distance Calculation

• To calculate the distance, the total time taken for the sound wave to travel to the object and return is measured.
• This total travel time is then divided by 2 to get the one-way distance.
• The formula is: Distance = (Travel Time × Speed of Sound) / 2

Arduino Code Example

• The code ensures proper communication through Serial.begin(9600).
• pinMode(TRIG_PIN, OUTPUT), pinMode(ECHO_PIN, INPUT) sets the trigger and echo pins for proper functionality.
• The code clears the trigger pin using digitalWrite(TRIG_PIN, LOW).
• Timing is crucial, so delayMicroseconds(2); and delayMicroseconds(10); control the pulse and subsequent readings.
• duration = pulseIn(ECHO_PIN, HIGH); reads the time the echo takes to return.
• distance = (duration * 0.0343) / 2; calculates the distance based on the travel time.
• This example calculates the distance, providing a clear output to the serial monitor using Serial.print().

Another Code Example (with Library)

• This example program uses a library (NewPing.h) for simpler distance calculations.
• Defines MAX_DISTANCE to control the sensor's range.
• NewPing() within the code initializes a new sonar object with the associated pins.

Example LCD Display Code

• Uses an I2C LCD library for controlling a Liquid Crystal display (LCD).
• LiquidCrystal_I2C Icd(0x27, 16, 2); establishes the LCD connection.
• Initializes LCD components and sets the display backlight on.
• Displays "Ultrasonic Sensor" message on the first line.
• Includes delay for visual clarity, preventing rapid scrolling.

Additional Notes

• These delay values are crucial for the sensor's accurate pulse sending and receiving. The calculation assumes a consistent speed of sound, and the sensor is properly calibrated.
• Zero value returned by the sensor implies the reading is outside the set maximum or minimum distance.