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Displaying Ultrasonic Reading

A 16x2 LCD screen is a common and convenient way to display real-time distance readings from an ultrasonic sensor, such as the HC-SR04, when using an Arduino Uno. By integrating the LCD, you can create a standalone project where distance measurements are shown directly without the need for a computer or serial monitor. The setup involves connecting the ultrasonic sensor and LCD to the Arduino, using a library to control the display, and programming the Arduino to process and output the readings.​

Materials Anchor

Materials

To display ultrasonic readings on a 16x2 LCD using an Arduino Uno, you'll need the following materials:

Components:

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1) Arduino Uno

  • The microcontroller board that processes sensor data and controls the LCD.

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2) HC-SR04 Ultrasonic Sensor
Measures distances using ultrasonic pulses.

  • Range: 2 cm to 400 cm

  • Accuracy: ±3 mm

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3) 16x2 LCD Screen

  • Displays the measured distance.

    • Can have button module or standard 16x2 stand-alone display​

    • If using the stand-alone 16x2 LCD, a 220Ω resistor will be needed for pin 15 to Power (+) of the Arduino

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4) Jumper Wires

  • For connecting the components.

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5) Breadboard

  • For organizing connections.

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6) USB Cable (Type A to B)

  • Connects the Arduino Uno to a computer for power and programming.

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Setup Anchor

Basic Setup

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Hardware Setup

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1) Ultrasonic Sensor to Arduino Uno:

  • VCC to 5V: Connect the VCC pin of the ultrasonic sensor to the Arduino's 5V pin.

  • GND to GND: Connect the GND pin of the ultrasonic sensor to the Arduino's GND pin.

  • Trigger to Pin 10: Connect the Trigger pin of the sensor to digital pin 10.

  • Echo to Pin 11: Connect the Echo pin of the sensor to digital pin 11.

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IF USING THE 16x2 SHIELD, WIRE IT AS FOLLOWS

2) Connect the LCD to the Arduino:

  • The LCD Shield has a 5V pin and a GND pin (Located Right of the buttons) these must be connected to the Arduinos 5V and GND pin respectively.

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  • The LCD has 16 pins. Wire them as follows:

    • Pin 1 (VSS): (GND '-') Leave unconnected, this is pre-routed via the Shields' board.

    • Pin 2 (VDD): (5V '+') Leave unconnected, this is pre-routed via the Shields' board.

    • Pin 3 (V0): (GND '+') Leave unconnected, this is pre-routed via the Shields' board.

    • Pin 4 (RS): Connect to Arduino digital Pin 8.

    • Pin 5 (RW): (GND '+') Leave unconnected, this is pre-routed via the Shields' board.

    • Pin 6 (E): Connect to Arduino digital Pin 9.

    • Pins 7-10 (D0-D3): Leave unconnected (for 4-bit mode).

    • Pins 11-14 (D4-D7): Connect to Arduino digital Pins 5, 4, 3, and 2 respectively.

    • Pin 15 (Backlight +): (5V '+') Leave unconnected, this is pre-routed via the Shields' board.

    • Pin 16 (Backlight -): (GND '-') Connect to common Arduino GND.

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IF USING THE 16x2 STAND-ALONE LCD DISPLAY

  • The LCD has 16 pins. Wire them as follows:

    • Pin 1 (VSS): (GND '-') Connect to Arduino's common ground pin.

    • Pin 2 (VDD): (5V '+') Connect to the 5V line of the Arduino.

    • Pin 3 (V0): (GND '+') Connect to the 5V line of the Arduino.

    • Pin 4 (RS): Connect to Arduino digital Pin 8.

    • Pin 5 (RW): (GND '-') This pin dictates if the LCD will read/write. Connect to Arduino's common ground pin for write mode.

    • Pin 6 (E): Connect to Arduino digital Pin 9.

    • Pins 7-10 (D0-D3): Leave unconnected (for 4-bit mode).

    • Pins 11-14 (D4-D7): Connect to Arduino digital Pins 5, 4, 3, and 2 respectively.

    • Pin 15 (Backlight +): (5V '+') Connect to the 5V line of the Arduino through a 220Ω resistor.

    • Pin 16 (Backlight -): (GND '-') Connect to Arduino's common ground pin.

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Software Setup

  • Use the Pre-Installed LiquidCrystal Library:

    • The standard LiquidCrystal library is pre-installed in the Arduino IDE. There is no need to install additional libraries.

Code

CODE

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CODE BREAK-DOWN

Code Break Down

#include <LiquidCrystal.h>

  • Includes the LiquidCrystal library, which provides functions to control the 16x2 LCD.

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LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

  • Initializes the LCD object and assigns the pins: RS to pin 7, E to pin 6, D4 to pin 5, D5 to pin 4, D6 to pin 3, and D7 to pin 2.

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const int trigPin = 9;

  • Defines digital pin 9 as the Trigger pin for the ultrasonic sensor.

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const int echoPin = 10;

  • Defines digital pin 10 as the Echo pin for the ultrasonic sensor.

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void setup() {

  • The setup() function runs once when the program starts and initializes the settings.

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pinMode(trigPin, OUTPUT);

  • Configures the Trigger pin as an output to send ultrasonic pulses.

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pinMode(echoPin, INPUT);

  • Configures the Echo pin as an input to receive reflected ultrasonic pulses.

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lcd.begin(16, 2);

  • Initializes the LCD with 16 columns and 2 rows.

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lcd.print("Ultrasonic Ready");

  • Displays the text "Ultrasonic Ready" on the LCD as a startup message.

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delay(2000);

  • Pauses for 2 seconds to allow the startup message to be visible.

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lcd.clear();

  • Clears the LCD display for new content.

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}
Ends the setup() function.

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void loop() {

  • The loop() function runs continuously, performing the main tasks.

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long duration = measureDistance();

  • Calls the measureDistance() function to measure the Echo signal duration and stores the result in duration.

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float distance = duration * 0.034 / 2;

  • Converts the measured duration into distance in centimeters using the speed of sound.

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lcd.setCursor(0, 0);

  • Sets the cursor to the first column of the first row on the LCD.

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lcd.print("Distance:");

  • Displays the label "Distance:" on the first row of the LCD.

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lcd.setCursor(0, 1);

  • Sets the cursor to the first column of the second row on the LCD.

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if (distance >= 2 && distance <= 400) {

  • Checks if the calculated distance is within the valid range of the sensor (2 to 400 cm).

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lcd.print(distance);

  • Displays the distance value on the second row of the LCD.

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lcd.print(" cm");

  • Appends " cm" to the distance value for clarity.

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} else {
Executes the following code if the distance is outside the valid range.

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lcd.print("Out of range");

  • Displays "Out of range" on the second row of the LCD when the distance is invalid.

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}
Ends the if-else statement.

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delay(500);

  • Pauses for 500 milliseconds before the next reading.

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}
Ends the loop() function.

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long measureDistance() {

  • Defines the measureDistance() function, which calculates the duration of the Echo signal.

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digitalWrite(trigPin, LOW);

  • Sets the Trigger pin LOW to stabilize the signal before sending a pulse.

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delayMicroseconds(2);

  • Pauses for 2 microseconds to ensure stability.

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digitalWrite(trigPin, HIGH);

  • Sets the Trigger pin HIGH to send an ultrasonic pulse.

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delayMicroseconds(10);

  • Holds the HIGH state for 10 microseconds, generating a valid ultrasonic pulse.

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digitalWrite(trigPin, LOW);

  • Stops the pulse by setting the Trigger pin LOW.

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return pulseIn(echoPin, HIGH);

  • Measures the duration of the Echo pin’s HIGH state, which corresponds to the round-trip time of the ultrasonic pulse, and returns the value.

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}
Ends the measureDistance() function.

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