Description
readStringUntil() reads characters from the serial buffer into a String. The function terminates if it times out (see setTimeout()).
Serial.readStringUntil() inherits from the Stream utility class.
Syntax
Serial.readStringUntil(terminator)
Parameters
Serial: serial port object. See the list of available serial ports for each board on the Serial main page.
terminator : the character to search for (char)
Returns
The entire String read from the serial buffer, up to the terminator character