Add WiFi to Arduino UNO

Connect your Arduino to the internet by adding ESP8266 WiFi Module!

The ESP8266 Wifi module is a complete Wi­Fi network where you can easily connect as a serving Wi- Fi adapter, wireless internet access interface to any microcontroller­ based design on its simple connectivity through Serial Communication or UART interface.

Adding this module to your Arduino UNO will open you to more and exciting projects.

What is the process?

There are a lot of ways to use ESP866 for communication. Some may use it to send / receive data online or regularly upload data. For this tutorial I will just show you how can we communicate to Arduino wirelessly using your phone (Android or iPhone) . This will be done offline so no need to have internet connection.

Our ESP8266 will serve as Access Point (AP Mode), meaning it will provide access to Wi-Fi network to other devices (stations) and connects them further to a wired network

The process it pretty simple. Use your phone to send any command to Arduino. With the help of ESP8266, everything will work wirelessly.

Built Circuit

Connect the pins more described on this Pin table

Follow these steps.

• connect the red wire to VIN(3.3V) to the +3.3V power from the microcontroller.
• connect the black wire to the ground.
• connect the green wire to the TX of the Wifi module and microcontroller
• connect the yellow wite to the RX of the wifi module and microcontroller

About the circuit

ESP8266 is strictly powered only to 3.3 V. More that that will destroy the module.

Connect the VIN to 3.3v to power up and also the ENABLE pin to enable the module.

TX is connected to RX which means whatever we want to Transmit in ESP8266 will Receive by Arduino UNO. And vise versa for RX to TX. Upon building this circuit, we now ready to start WIFI with Arduino UNO.

Talk to Module

Communication with ESP8266 is via Attention Command or AT Commands.

Check the AT Commands table attached to review the codes.

Setting your board

Once everything is set up, you would notice that your ESP8266 Wifi will be available within the range of your phone.

1. Upload the sketch sample attached here to your Arduino UNO.

2. Download TCP Client for Android

3. From your phone, Connect to your ESP8266 Wifi

4. Once connected, get the Static IP address, you can check the IP by going to Wifi Settings of your phone, and click the network info.

5. Open TCP Client you downloaded earlier.

6. Create connection by clicking connect , Add IP and port 80.

7. Wait for the TCP Console to say "Connected".

Once connected send request by typing the following code to TCP Client:

esp8266: <any AT Commands>

Or turn on built-in LED using command

LEDON

Or turn off built-in LED using command

LEDOFF

Or just say

HELLO

You can change what response from what you send depending on the logic you put into the code.

About the Code

All our request will be read and parse on the loop() function

if(wifiSerial.available()>0){ 
   String message = readWifiSerialMessage(); 
   if(find(message,"esp8266:")){ 
      String result = sendToWifi(message.substring(8,message.length()),responseTime,DEBUG); 
     if(find(result,"OK")) 
       sendData("n"+result); 
     else 
       sendData("nErrRead");               //At command ERROR CODE for Failed Executing statement 
   }else 
   if(find(message,"HELLO")){  //receives HELLO from wifi 
       sendData("\nHI!");    //arduino says HI 
   }else if(find(message,"LEDON")){ 
     digitalWrite(13,HIGH); 
   }else if(find(message,"LEDOFF")){ 
     digitalWrite(13,LOW); 
   } 
   else{ 
     sendData("nErrRead");                 //Command ERROR CODE for UNABLE TO READ 
   } 
 } 

You can see from above that I used my function find(<received message>,<message you want to find> ) to interpret the message and to tell arduino which code to call.

If you want to communicate with Arduino UNO or ask todo something, just add your condition. for example :

if(find(message,"MY CODE")){
     // I found 'MY CODE' from received message
     // lets do something here
}
if(find(message,"A")){
     // I found 'A' from received message
     // lets do something here
}

I added some function to communicate with ESP8266.

/* 
* Name: sendData 
* Description: Function used to send string to tcp client using cipsend 
* Params:  
* Returns: void 
*/ 
void sendData(String str){ 
 String len=""; 
 len+=str.length(); 
 sendToWifi("AT+CIPSEND=0,"+len,responseTime,DEBUG); 
 delay(100); 
 sendToWifi(str,responseTime,DEBUG); 
 delay(100); 
 sendToWifi("AT+CIPCLOSE=5",responseTime,DEBUG); 
} 
/* 
* Name: find 
* Description: Function used to match two string 
* Params:  
* Returns: true if match else false 
*/ 
boolean find(String string, String value){ 
 if(string.indexOf(value)>=0) 
   return true; 
 return false; 
} 
/* 
* Name: readSerialMessage 
* Description: Function used to read data from Arduino Serial. 
* Params:  
* Returns: The response from the Arduino (if there is a reponse) 
*/ 
String  readSerialMessage(){ 
 char value[100];  
 int index_count =0; 
 while(Serial.available()>0){ 
   value[index_count]=Serial.read(); 
   index_count++; 
   value[index_count] = '