This sample code is for Controlling Arduino Using Voice Tutorial by Cytron Technologies Sdn. Bhd.

voice_bluetooth.ino

/*
This example code is for Controlling Arduino Using Voice Tutorial.
Product page:
  Maker UNO: https://www.cytron.io/p-maker-uno
Created by:
  16/07/18  Suad Anwar, Cytron Technologies
 */

#include <SoftwareSerial.h>
SoftwareSerial HC06Serial(11, 10); // (RX,TX)
String value;

int yellow = 4;
int red = 5;
int green = 6;

void setup() {
  pinMode(yellow, OUTPUT);  
  pinMode(red, OUTPUT);
  pinMode(green, OUTPUT);
  Serial.begin(9600);       // start serial communication at 9600bps
  HC06Serial.begin(9600);
}

void loop() {
  Serial.println(value);
  if (HC06Serial.available())
  {
    value = HC06Serial.readString();

    if (value == "on") {
      digitalWrite(yellow, HIGH);
      digitalWrite(red, HIGH);
      digitalWrite(green, HIGH);
    }

    if (value == "off") {
      digitalWrite(yellow, LOW);
      digitalWrite(red, LOW);
      digitalWrite(green, LOW);
    }
    
    if (value == "yellow on") {
      digitalWrite(yellow, HIGH);
    }

    if (value == "red on") {
      digitalWrite(red, HIGH);
    }

    if (value == "green on") {
      digitalWrite(green, HIGH);
    }
    
     if (value == "yellow off") {
      digitalWrite(yellow, LOW);
    }

    if (value == "red off") {
      digitalWrite(red, LOW);
    }

    if (value == "green off") {
      digitalWrite(green, LOW);
    }
  }
}