Serial.readBytesUntil() Function in Arduino Programming

When it comes to programming with Arduino, there are many functions that you can use to manipulate input and output. One main Arduino function is Serial.readBytesUntil(), which allows you to read data from a stream until a specific character is found. This function helps reading data from serial devices till we find the required data.

This writeup compiles the Serial.readBytesUntil() function in depth. We will discuss what it is, how it works, and cover Arduino code that explains how to use it in Arduino code.

Serial.readBytesUntil()

The Serial.readBytesUntil() function is a part of the Arduino Serial class. This function reads data from a stream until it finds a specific character or a maximum number of bytes. Once the character or maximum number of bytes is found, the function stops reading and returns the data it has read.

The Serial.readBytesUntil() function terminates whenever following conditions are met:

When function detect a terminator character
The defined buffer length is reached
The set time is passed or Times out

This function doesn’t return the terminator character it only returns data up to the last character before the terminator. When 0 is returned by this function it means no valid data is found.

Syntax

The Serial.readBytesUntil() function has the following syntax:

Serial.readBytesUntil(char terminator, char* buffer, size_t length);

Parameters

Following are the parameters of the function Serial.readBytesUntil():

Terminator Character: The character that the function will stop reading at.
buffer: In buffer the read serial data is The allowed data type is an array of char or byte.
length: The maximum number of bytes to read. The allowed data type is int.

Return

The number of bytes placed in the buffer.

Notes: In return data the terminator character is discarded by the function Serial.readBytesUntil() from the data stream.

Example Arduino Code

Following Arduino code explain use of Serial.readBytesUntil() function:

void setup() {
Serial.begin(9600); // Initialize the serial connection with a baud rate of 9600
}

void loop() {
byte buffer[5]; // Define a byte array to store the incoming data
int numBytes = Serial.readBytesUntil('\n', buffer, 5); // Read incoming data from the serial connection until a newline character is encountered

if (numBytes > 0) { // Check if any bytes were read
Serial.print("Received Character: ");
Serial.write(buffer, numBytes); // Print the received data to the serial monitor
Serial.println();
}
}

In the setup() function baud rate will establish serial communication.

In the loop() function, we first define a byte array called ‘buffer’. This array will be used to store the incoming data read from the serial connection.

Next, we call the Serial.readBytesUntil() function, which reads incoming data from the serial connection until it encounters a newline character (‘\n’). Next argument is the length of the buffer which will take a maximum of 5 bytes of data at a time.

The returned byte is stored in the ‘numBytes’ variable. In case if the received data is greater than the buffer length the data will be terminated and will be sent in the next data stream.

Output

Conclusion

The Serial.readBytesUntil() function in Arduino programming reads bytes from a serial input stream until a specified terminator character is received. The function gives total bytes read and stores them in a provided buffer. Read the article to get more information related to Serial.readBytesUntil() Function.

Serial.readBytesUntil() Function in Arduino Programming