HC-SR04 and LCD Circuit Problem

Question

I was designing a circuit that measure distance using HC-SR04 and display it into a LCD.This circuit also have 4 LEDs indicator.But i have a problem.The LEDs doesn't turn on.The LCDs backlight turn on, but it didnt display anything. Btw, i'm using LCD with I2C module.Here is the code:

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
#define trigPin 6
#define echoPin 7
int led5cm = 8;
int led7cm = 9;
int led10cm = 10;
int ledoor = 11; //ledoor means LED Out of Range
void setup() { // put your setup code here, to run once: lcd.begin(16,2); lcd.setCursor(0,0);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(led5cm, OUTPUT);
  pinMode(led7cm, OUTPUT);
  pinMode(led10cm, OUTPUT);
}
void loop() {
  long duration, distance;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration / 2) / 29.1;
  if (distance <= 5)
  { lcd.println("Distance < 5 CM");
    lcd.print("Distance = ");
    lcd.print(distance);
    lcd.print(" CM");
    digitalWrite(led5cm, HIGH);
    digitalWrite(led7cm, LOW);
    digitalWrite(led10cm, LOW);
    digitalWrite(ledoor, LOW);
    lcd.clear();
    delay(200);
  } else if (distance >= 5 || distance <= 7) {
    lcd.println("Distance < 7 CM");
    lcd.print("Distance = ");
    lcd.print(distance);
    lcd.print(" CM");
    digitalWrite(led5cm, LOW);
    digitalWrite(led7cm, HIGH);
    digitalWrite(led10cm, LOW);
    digitalWrite(ledoor, LOW);
    lcd.clear();
    delay(200);
  }
  else if (distance >= 7 || distance <= 10) {
    lcd.println("Distance < 10 CM");
    lcd.print("Distance = ");
    lcd.print(distance);
    lcd.print(" CM");
    digitalWrite(led5cm, LOW);
    digitalWrite(led7cm, LOW);
    digitalWrite(led10cm, HIGH);
    digitalWrite(ledoor, LOW);
    lcd.clear();
    delay(200);
  }
  else if (distance > 10) {
    lcd.println("Out of Range");
    lcd.print("Distance = ");
    lcd.print(distance);
    lcd.print(" CM");
    digitalWrite(led5cm, LOW);
    digitalWrite(led7cm, LOW);
    digitalWrite(led10cm, LOW);
    digitalWrite(ledoor, LOW);
    lcd.clear();
    delay(200);
  }
}

Can you please help me solve this problem? Thank you very much!!

Answer 1

To make your LCD work, add code like the following in setup(). (Substitute appropriate values in place of LCDcols and LCDrows, or give them appropriate values via const int ... or enum { ... }; statements.)

  lcd.begin(LCDcols, LCDrows);
  lcd.setBacklightPin(3,POSITIVE); // Might not need this, since info appears to be included in lcd declaration
  lcd.setBacklight(HIGH);
  lcd.clear();          // Clear the display
  lcd.home();

To make the LEDs work better, you may need to change the || connectives in some of the if statements to &&. An if condition with terms joined by ||, OR, is true if any of its terms are true; with terms joined by &&, AND, all of its terms must be true for the condition to be true.

For example, the condition (distance >= 5 || distance <= 7) is true if distance is 5 or more, or 7 or less; in other words, is always true.