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Interrupts

          Interrupts example for Arduino Uno #include<avr/sleep.h> #include <avr/power.h> volatile int f_wdt=1; int flag=false; void setup() {   // put your setup code here, to run once:   pinMode(LED_BUILTIN,OUTPUT);   digitalWrite(LED_BUILTIN,LOW);   attachInterrupt(digitalPinToInterrupt(2), blink, CHANGE);   Serial.begin(9600); //LowPower.sleep(500000); watch(); } void enter_sleep() {   set_sleep_mode(SLEEP_MODE_PWR_DOWN);   sleep_enable();   sleep_mode();   sleep_disable();   sleep_enable();   power_all_enable();    } ISR(WDT_vect){   if(f_wdt==0)      f_wdt=1;    } void watch() {   MCUSR&=~(1<<WDRF);   WDTCSR |= (1<<WDCE) | (1<<WDE);   WDTCSR  = (1<<WDP3) | (0<<WDP2) | (0<<WDP1) | (1<<WDP0);   WDTCSR |= _BV(WDIE); } void blink() {   f...
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MQTT basic publish and subscribe commutation each other

FIRST device PUBLISH data #include <WiFi.h> #include "Adafruit_MQTT.h" #include "Adafruit_MQTT_Client.h" #define AIO_SERVER      "io.adafruit.com" #define AIO_SERVERPORT  1883 #define AIO_USERNAME  "suresh7799" #define AIO_KEY  "6d84f0c9edca4461a7212d74c6099175" WiFiClient client; Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY); boolean MQTT_connect(); boolean MQTT_connect() {   int8_t ret;   if (mqtt.connected()) {     return true; }     uint8_t retries = 3;     while ((ret = mqtt.connect()) != 0) {       mqtt.disconnect();       delay(2000);       Serial.println("conneting to mqtt");       retries--;       if (retries == 0)       {         Serial.println("time out for mqtt");         return false; }}   ...
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WifFI basics for esp32 and esp8266

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WiFi connections key words   1. WiFi.status();    Syntax:        while ((!(WiFi.status() == WL_CONNECTED))){        Serial.print("..");     delay(300);   }  2. WiFi.localIP()    Syntax:      WiFi.localIP() #include <WiFi.h> void setup() { Serial.begin(9600);   WiFi.begin("ssid","password");   Serial.println("Start");   Serial.print("please wait connecting to WIFI");   while ((!(WiFi.status() == WL_CONNECTED))){        Serial.print("..");     delay(300);   }   Serial.println("connected ");   Serial.println("IP address :");   Serial.print((WiFi.localIP())); } Result Server creation steps and client  1. WiFiSever sever(80);  port creation in WiFi making esp as sever and ip address as a client 2, WiFiClient client ;   creating client to WiFi  3....
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controlling of led using voice commonds using bluetooth

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   C ontrolling of led using voice commands through  Bluetooth code for Arduino board void setup() {   // put your setup code here, to run once: pinMode(13,OUTPUT); Serial.begin(9600); } String voice; String voice1="hi"; void loop() {   // put your main code here, to run repeatedly: if(Serial.available()>0) {   voice="";   delay(2);   voice=Serial.readString();   delay(2);   Serial.println(voice);   if(voice==voice1)   {     Serial.println("ok");     digitalWrite(13,HIGH);   }else if(voice=="stop")   digitalWrite(13,LOW); } } OUtput
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controlling of led using Bluetooth through string compare

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 controlling of led using Bluetooth and Arduino through string compare  code Arduino program String data; void root(String ); void setup() {   pinMode(13,OUTPUT);   digitalWrite(13,LOW);   Serial.begin(9600);   } void loop() {   root(data);   if(Serial.available())   {     data=Serial.readString();     Serial.println(data);     if(data== '4')     digitalWrite(13,HIGH);     else     digitalWrite(13,LOW);       } } void root(String data1) {   String str="mystringname"; if(Serial.available()) {   String data1=Serial.readString();  // Serial.write(data1);   Serial.println(data1);   if(data1==str)   {     digitalWrite(13,HIGH);   }     else    {     digitalWrite(13,LOW);   } } } OUTPUT 13 th led will high whe...
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