Arduino Serial Read String or Line from Serial Monitor with ReadString Function

Arduino Serial Read String or Line – Serial.readString()

• Arduino Serial.readString() Function reads the multiple bytes from the Serial Port received buffer into a String variable.
• The readString function will read all the data received until the timeout.
• The function return the String data type.
• The readString() function will complete by timeout time, by default it is one second.

Serial.readString() function is useful in copy all the received data in the String variable, for further analysis or testing the command received.

Arduino Serial Read String From Serial Port Monitor

Ones the data is available in the string variable we can use string functions for further analysis, like indexOf() function to search the particular word is exist or not.

The readString function return the String data type. The function terminate after timeout, which is one second by default.

We will use serial monitor tool available in the Arduino IDE to send the string to the Arduino board.

Arduino Serial ReadString Function Example

In this small project code we will send some data from serial monitor and return back the same data with Serial.println() function.

/*
    Serial.readString() test program.
	Author: Nilesh Chaurasia
    https://elextutorial.com
*/
void setup() 
{
	Serial.begin(9600); // Set the baud rate to 9600
}
void loop() 
{
	String s1 = Serial.readString();// s1 is String type variable.
	Serial.print("Received Data => ");
	Serial.println(s1);//display same received Data back in serial monitor.
	delay(500);
}   
				 

/*
    Serial.readString() program to device control from serial command "on" / "off".
	Author: Nilesh Chaurasia
    https://elextutorial.com
*/
void setup() 
{
	Serial.begin(9600); // Set the baud rate to 9600
	pinMode(13,OUTPUT);
}
void loop() 
{
	String s1 = Serial.readString();// s1 is String type variable.
	Serial.print("Received Data => ");
	Serial.println(s1);//display same received Data back in serial monitor.
	if(s1.indexOf("on")>=0)
	{
		digitalWrite(13,HIGH);
	}
	if(s1.indexOf("off")>=0){
		digitalWrite(13,LOW);
	}
	delay(100);
}