1.	Design and implement a system using Arduino Board where pressing a push buttontoggles an LED ON and OFF.
int led = 13;
 int button = 2; 
 int state = 0;
  void setup() {  
     pinMode(led, OUTPUT); 
    pinMode(button, INPUT_PULLUP);
     } 
     void loop() { 
        if (digitalRead(button) == LOW) {  
             state = !state;   
               digitalWrite(led, state); 
                   delay(300);   }
}
2.
3.	Develop a motion detection system using a PIR sensor interfaced with Arduino board.
int pir = 2, 
led = 13, 
buzzer = 4;
 void setup() {
     pinMode(pir, INPUT);
        pinMode(led, OUTPUT);  
         pinMode(buzzer, OUTPUT);
          } void loop() { 
              if (digitalRead(pir)) {
                digitalWrite(led, HIGH); 
                    digitalWrite(buzzer, HIGH);
                       } else {   
                          digitalWrite(led, LOW);  
                          digitalWrite(buzzer, LOW); 
                               }
}

5.	Build an IoT system using NodeMCU and DHT11 sensor to measure temperature andhumidity and upload to ThingSpeak.
#include <ESP8266WiFi.h>
#include "DHT.h"
 #include <ThingSpeak.h> 
 const char* ssid = "YourWiFi"; 
 const char* pass = "YourPassword"; 
 WiFiClient client;
  unsigned long ch = YOUR_CHANNEL_ID;
   const char* key = "YOUR_API_KEY"; 
   DHT dht(D2, DHT11); 
   void setup() {  
     WiFi.begin(ssid, pass);
        ThingSpeak.begin(client);   
        dht.begin();
         } void loop() {  
           float t = dht.readTemperature();  
            float h = dht.readHumidity(); 
              ThingSpeak.setField(1, t);
  ThingSpeak.setField(2, h);
  ThingSpeak.writeFields(ch, key);
  delay(20000); }
6. Build an IoT system using NodeMCU and DHT11 sensor to measure temperature and humidity with buzzer alert.
#include "DHT.h"
#define DHTPIN D2
#define DHTTYPE DHT11
#define BUZZER D3
 DHT dht(DHTPIN, DHTTYPE); void setup() {   pinMode(BUZZER, OUTPUT);   dht.begin(); } void loop() {   float t = dht.readTemperature();   if (t > 30) digitalWrite(BUZZER, HIGH);   else digitalWrite(BUZZER, LOW);   delay(2000); }
7.	Create a distance monitoring system using Raspberry Pi and ultrasonic sensor.
import RPi.GPIO as GPIO, time TRIG=23; ECHO=24
GPIO.setmode(GPIO.BCM)
GPIO.setup(TRIG,GPIO.OUT) GPIO.setup(ECHO,GPIO.IN) while True:     GPIO.output(TRIG, True)     time.sleep(0.00001)     GPIO.output(TRIG, False)     while GPIO.input(ECHO)==0: start=time.time()     while GPIO.input(ECHO)==1: end=time.time()     dist=(end-start)*17150     print("Distance:", round(dist,2),"cm")     time.sleep(1)
8.	Simulate a distance monitoring system in Wokwi using Raspberry Pi and ultrasonicsensor.
#define TRIG 2
#define ECHO 3 #define LED 4
long dur; int dist; void setup() {   pinMode(TRIG, OUTPUT);   pinMode(ECHO, INPUT);   pinMode(LED, OUTPUT);   Serial.begin(9600); } void loop() {
  digitalWrite(TRIG, LOW); delayMicroseconds(2);   digitalWrite(TRIG, HIGH); delayMicroseconds(10);   digitalWrite(TRIG, LOW);   dur = pulseIn(ECHO, HIGH);   dist = dur * 0.034 / 2;   Serial.println(dist);   if (dist > 20) digitalWrite(LED, HIGH);   else digitalWrite(LED, LOW);   delay(500); }
9.	Simulate a distance monitoring system in Wokwi using Raspberry Pi and ultrasonicsensor.
Use the same code as Q8.
10.	Design and implement a stepper motor control system using ESP8266 (NodeMCU).
#include <Stepper.h>
#define STEPS 200 Stepper stepper(STEPS, D1, D2, D3, D4); void setup() {} void loop() {   stepper.setSpeed(50);   stepper.step(200);   delay(1000);   stepper.step(-200);   delay(1000); }
11.	Simulate a stepper motor control system in Wokwi using NodeMCU.
Same as Q10.
12.	Develop a color detection system using TCS3200 and ESP8266 (NodeMCU) that sendscolor data to Blynk.
#include <BlynkSimpleEsp8266.h> char auth[] = "YourAuth"; char ssid[] = "WiFi"; char pass[] = "Pass"; void setup() {   Blynk.begin(auth, ssid, pass);
  Serial.begin(9600); } void loop() {
  int color = analogRead(A0);   Blynk.virtualWrite(V1, color);   delay(1000); }
13.	Develop a color detection system using TCS3200 and NodeMCU.
int color; void setup() {   pinMode(A0, INPUT);   Serial.begin(9600); } void loop() {   color = analogRead(A0);   Serial.println(color);   delay(1000); }
14.	Implement a gas leakage monitoring system using MQ2 sensor and NodeMCU.
#define MQ2 A0 #define BUZZER D1 void setup() {   pinMode(MQ2, INPUT);   pinMode(BUZZER, OUTPUT); } void loop() {
  int gas = analogRead(MQ2);   if (gas > 300) digitalWrite(BUZZER, HIGH);   else digitalWrite(BUZZER, LOW);   delay(1000);
}
15.	Implement a gas leakage monitoring system using MQ2 sensor.
Same as Q14 without NodeMCU WiFi functions.
16.	Implement a simple LED control system using NodeMCU and Blynk app.
#include <BlynkSimpleEsp8266.h> char auth[] = "YourAuth"; char ssid[] = "WiFi"; char pass[] = "Pass"; int led = D2; void setup() {   pinMode(led, OUTPUT);   Blynk.begin(auth, ssid, pass);
} BLYNK_WRITE(V1) {   int pinValue = param.asInt();   digitalWrite(led, pinValue); } void loop() {   Blynk.run();
}