example_simple_parser.ino

/*  <--- Arduino SbS Simple String Parser example --->
 * 
 * This sketch shows how to receive a String from the serial 
 * monitor and parse it so that the first and second characters
 * are returned. Once you have this information, you can use
 * it to control connected devices, like an array of LEDs.
 * 
 * For example, if you type '03O' (letter 'O'), the parses
 * will detect '3' as the pin number and 'O' as the
 * command, and will turn On an LED conected to digital pin 3.
 * 
 * 
 * Components  used in this sketch
 * ----------
 *  - Arduino Uno
 *  - Breadboard
 *  - 3 x 5V LED 
 *  - 3 x 220 Ohm resistor
 
 *      
 *  Libraries
 *  ---------
 *  - None
 *
 * Connections 
 * -----------
 *  Connect the LEDs to any available digital pins, 
 *  except for 0 and 1 (used for serial communications).
 *  
 * Other information
 * -----------------
 * Reminder: The long leg of the LED connects to 5V
 * through the resistor and the short leg connects 
 * to Ground.
 *  
 *  
 *  Created on February 24 2017 by Peter Dalmaris
 * 
 */

String val; // variable to receive data from the serial port
String pin;
int ledpin1 = 7; // LED connected to pin 7 
int ledpin2 = 8; // LED connected to pin 8 
int ledpin3 = 9; // LED connected to pin 9

void setup() {
  pinMode(ledpin1, OUTPUT);  
  pinMode(ledpin2, OUTPUT);  
  pinMode(ledpin3, OUTPUT);  
  Serial.begin(9600);
}

void loop() {

  if( Serial.available() )           // If data is available to read
  {
    val = Serial.readString();       // Read a string for the monitor and store it in 'val'
    Serial.print(val);
    Serial.print("Pin number:");
    pin = val.substring(0,2);       // Get the first two characters, these make up the pin number
                                    // which can be any valid pin number (0 .. 13 for the Uno)
    Serial.println(pin);            
    Serial.print("Command:");
    Serial.println(val[2]);         // Simply read the character in position 2 of the string
                                    // this is the instruction. For no particular reason, an 'O'
                                    // will turn on the LED
    if (val[2] == 'O')
    {
      Serial.print("Turning on LED at pin ");
      Serial.println(pin);
      digitalWrite(pin.toInt(), HIGH);      // The digitalWrite function needs an integer in the
                                        // first parameter, so convert the 'pin' string to 
                                        // an int using the 'toInt()' function
    } else 
    { 
      Serial.print("Turning off LED at pin ");
      Serial.println(pin);
      digitalWrite(pin.toInt(), LOW);
     }
  }
}