Write a program for Interfacing Air Quality Sensor-pollution (e.g. MQ135) to Arduino board and display dots generated by sensor on LCD.
Last Updated : 16 Jul 2025
Solution:
#include <LiquidCrystal.h>
#define mq135pin A1 // MQ135 sensor pin
const int rs = 11; // RS pin for LCD
const int en = 10; // EN pin for LCD
const int d4 = 9; // Data pin 4 for LCD
const int d5 = 8; // Data pin 5 for LCD
const int d6 = 7; // Data pin 6 for LCD
const int d7 = 6; // Data pin 7 for LCD
LiquidCrystal lcd(rs, en, d4, d5, d6, d7); // Initialize LCD
void setup(){
lcd.begin(16, 2); // Set up LCD with 16x2 display
}
void loop(){
int airquality = analogRead(mq135pin); // Read MQ135 sensor value
int dot = map(airquality, 0, 1023, 0, 16); // Map sensor value to number of dots
lcd.clear(); // Clear the display before printing new data
for (int i = 0; i < dot; i++) {
lcd.print("."); // Print dots based on air quality
}
delay(5000); // Wait 5 seconds before the next reading
}
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