Arduino - LCD Keypad Shield + HC-SR04 Ultrasonic Sensor

Source Code

	#include <LiquidCrystal.h>
	// HC-SR04 pins
	int trigPin = 12;
	int echoPin = 13;
	// Keypad Shield LCD
	LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
	void setup() {
	pinMode(trigPin, OUTPUT); // trig as OUTPUT
	pinMode(echoPin, INPUT); // echo as INPUT
	lcd.begin(16, 2);
	}
	void loop() {
	float duration, distance;
	// Send ultrassound. After sent, echo waits in HIGH state.
	digitalWrite(trigPin, HIGH);
	delayMicroseconds(10);
	digitalWrite(trigPin, LOW);
	// Stores the time echoPin held HIGH
	duration = pulseIn(echoPin, HIGH);
	// Calculate the distance with the time
	// The time the ultrasonic waves have been sent back. (HIGH time)
	distance = ((float)(340 * duration) / 10000) / 2;
	// ignore bad values
	if (distance > 1000) return;
	if (distance < 2) return;
	// print distance
	lcd.setCursor(0, 0);
	lcd.print("Distance: ");
	lcd.setCursor(0, 1);
	lcd.print(distance);
	lcd.print("cm ");
	delay(500);
	}

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