learning-uno/lessons/lesson61.cpp

// Lesson 61. Ultrasonic Sensor with LCD Display
// https://www.youtube.com/watch?v=nC2CDaqJomA


#include <Arduino.h>
#include <LiquidCrystal.h>

const int rs = 7, en = 8, d4 = 9, d5 = 10, d6 = 11, d7 = 12;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

int trigPin = 2;
int echoPin = 3;
int pingTravleTime;
float distance;
const int pulsTime = 40;                // uS
const float pingTimeToDistance = 0.017; // uS to cm, travletime[s] * 340 m/s / 2

int numReadings = 50;
float averageMeasurements;
float averageTime;
float bucketDist = 0.0;
float bucketTime = 0.0;

int buttonPin = A0;
int buttomState;

int setTime = 500;
int dt = 1000;

void setup()
{
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("Measurring Distance");

  delay(setTime);

  lcd.begin(16, 2);
  lcd.print("Hello, World!");

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buttonPin, INPUT);
  digitalWrite(buttonPin, HIGH);
}

void loop()
{
  // put your main code here, to run repeatedly
  buttomState = digitalRead(buttonPin);
  while (buttomState == HIGH)
  {
    lcd.setCursor(0, 0);
    lcd.print("Place the Target");
    lcd.setCursor(0, 1);
    lcd.print("Press the Button");
    buttomState = digitalRead(buttonPin);
  }

  {
    bucketDist = 0.0;
    bucketTime = 0.0;

    for (int i = 0; i < numReadings; i++)
    {
      digitalWrite(trigPin, LOW);
      delayMicroseconds(pulsTime);
      digitalWrite(trigPin, HIGH);
      delayMicroseconds(pulsTime);
      digitalWrite(trigPin, LOW);
      pingTravleTime = pulseIn(echoPin, HIGH);
      delay(25);

      distance = pingTravleTime * pingTimeToDistance; // Travel time to distance in cm

      bucketDist = bucketDist + distance;
      bucketTime = bucketTime + pingTravleTime;

    }

    averageMeasurements = bucketDist / numReadings;
    averageTime = bucketTime / numReadings;

    Serial.print("Ping Time and Distance:");
    Serial.print("Ping Time: ");
    Serial.print(averageTime);
    Serial.print(" Distance: ");
    Serial.print(averageMeasurements);
    Serial.println(" cm");

    // Display on LCD
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Ping Time: ");
    lcd.print(averageTime);
    lcd.print("us");
    lcd.setCursor(0, 1);
    lcd.print("Distance: ");
    lcd.print(averageMeasurements);
    lcd.print("cm");
  }
}