Arduino Serial LED Control from Computer

Hello, 

Arduino also works on manual commands by the user who controls it and may turn on/off or control the output digital pins and hence the device connected at that pin.

You may also read: Wireless Control of LED with Arduino and Smartphone

Mostly, alphabet/numeric keys from the computer keyboard are used to give commands to the Arduino to control the output pins through the serial communication.

Let’s get started with the Arduino serial communication project.

Things you will need:

1. Arduino Uno

2. Breadboard

3. Arduino Cable

4. LED 5V (red, yellow or green)

5. Jumper cables

6. Resistor – 220 ohm

Step 1: Making the Circuit

You may connect the LED or skip this step as the Arduino Uno R3 (a common development board) comes with inbuilt LED at pin 13. But, we shall make the circuit so as to understand the pins connections and get hands-on experience.

1. Fix the LED on the breadboard such that the two legs of the LED do not short.

2. Connect the pin 13 of the Arduino to the positive terminal (the longer leg) of the LED with jumper cable.

3. Connect the Gnd of the Arduino to the negative terminal (the shorter leg) of the LED with jumper cable.

4. Connect the 220 ohm resistor between pin 13 and the positive of the LED so as to protect the LED from getting damaged.

Step 2: Uploading the Code

Enter the following code into the Arduino IDE or paste it. The code would be called by the Arduino to check whether the value entered by us matches with the variable in the code. If it does, the corresponding operation would be performed.

int led = 13; // Pin 13

    

void setup()

{

    pinMode(led, OUTPUT); // Set pin 13 as digital out

    

    // Start up serial connection

    Serial.begin(9600); // baud rate

    Serial.flush();

}

    

void loop()

{

    String input = "";

    

    // Read any serial input

    while (Serial.available() > 0)

    {

        input += (char) Serial.read(); // Read in one char at a time

        delay(5); // Delay for 5 ms so the next char has time to be received

    }

    

    if (input == "on")

    {

        digitalWrite(led, HIGH); // on

    }

    else if (input == "off")

    {

        digitalWrite(led, LOW); // off

    }

}

Now, connect the Arduino to the computer via the USB cable provided and choose the correct COM port.  Click on the upload button from the toolbar. And, wait till the software says “Done Uploading”.

Step 3: LED Control from Computer

Once the code is uploaded, it is time to check the LED output as we desire it to be. If we command it to turn on, it should be turned on and if we command it to turn off, it should be turned off.

Open the serial monitor from the Arduino software (Tools>Serial Monitor), it may appear in a new window. You may also open it by using commands : Ctrl+Shift+M. The serial monitor would be initially blank and has an input box on the top.

Enter the term “on” and hit enter.

Whoa! Did you see that? The LED just turned on immediately without delay.

Now, enter the term “off” and hit enter.

Oh, now the LED just turned off. So you get the idea that you may control the output pins from your computer and Arduino works as you wish.

Congratulations! You have just completed your Arduino Project – simple, fun and easy.

Add another commands for example “yes”, “no” etc or even command multiple LED with just a little update in the code.

You may also read: Wireless Control of LED with Arduino and Smartphone

Stay Hungry! Stay Foolish!