Two-way serial communication with Arduino

In this video I show you how to send and receive data between an Arduino and your computer. I show you how to use the switch-case and if() statement. I also show how to format your data to make it easier to handle on the computer.

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Arduino source code

bool enablerun = false;
bool newData = false;
String sin1, sin2; //sin = Serial INput
float num1, num2; //num = number
char receivedCommand; //received character as a command
int cycles = 0;
 
void setup()
{
  Serial.begin(9600); //define baud rate
  Serial.println("Testing Serial Commands"); //print a message
 
 
  Serial.println("m = mirror");
  Serial.println("a = add two numbers");
  Serial.println("c = count");
  Serial.println("d = send formatted data");
  Serial.println("s = stop sending data");
  Serial.println("----------------------------");
}
 
void loop()
{
  //Comment out one of these below. Either use the Switch-Case or the if()
  CheckSerialSwitchCase(); //This is with Switch - Case
 
  //CheckSerialIF(); //This is with IF()
  //---------------------------------------------------
 
 
  sendFormattedData(); //This is a function
 
}
 
 
void CheckSerialIF() //Checking the serial port via IF statements
{
  if (Serial.available() > 0) //if something comes from the Serial. This part only checks the serial.
  {    
    receivedCommand = Serial.read(); // this will read the command character
    newData = true; //this creates a flag and says there's a data coming
  }
 
  if (newData == true) //if we received something (see above)
  {
   
    if (receivedCommand == 'm') //this is the mirror part
    {
      sin1 = Serial.readString(); //Read one serial input
 
      Serial.print("Message was: ");
      Serial.println(sin1);
 
    }
   
    if (receivedCommand == 'a') //addition
    {      
      //example: a 42 1
      while (!Serial.available());
      num1 = Serial.parseFloat();
 
      num2 = Serial.parseFloat();
     
      addTwoNumbers(num1, num2);
 
    }
   
    if (receivedCommand == 'c') //Counting
    {
      //example: c 5
      while (!Serial.available());      
      num1 = Serial.parseFloat();
 
      counterCode(num1);
 
    }
 
    if (receivedCommand == 'd') //Sending formatted data
    {
      enablerun = true; // this enables the function for sending formatted data
    }
 
   
    if (receivedCommand == 's') //immediately stops the code
    {
      enablerun = false;
      Serial.println("Stopped!");
 
    }
   
  }
  //after we went through the above tasks, newData becomes false again, so we are ready to receive new commands again.
  newData = false;
}
 
void CheckSerialSwitchCase() //Checking the serial port via Switch-Case
{
  if (Serial.available()) { //If there are bytes/characters coming through the serial port
 
    char commandcharacter = Serial.read(); //read the character for the command
   
    switch (commandcharacter) { //we read a character which can
   
    case 'm': //m = "mirror"; we send back the received stuff
 
      sin1 = Serial.readString(); //Read one serial input
 
      Serial.print("Message was: ");
      Serial.println(sin1);
     
      break;
 
    case 'a': //a = "addition"; we add two numbers      
      //example: a 42 1
      while (!Serial.available());
     
      num1 = Serial.parseFloat();
 
      num2 = Serial.parseFloat();
     
      addTwoNumbers(num1, num2);
     
      break;
     
 
    case 'c': //c as count
      //example: c 5
      while (!Serial.available());
           
      num1 = Serial.parseFloat();
 
      counterCode(num1);
      break;
   
     
    case 'd': //we request formatted data
     
      enablerun = true; // this enables the function for sending formatted data      
 
    break;
 
    case 's': //s = stop; we make enablerun false, so we stop receiving data.
 
      enablerun = false;
      Serial.println("Stopped!");
 
    break;
    }
  }
}
 
 
void addTwoNumbers(float sin1, float sin2)//This function adds two numbers and prints it on the serial
{
  float result; //create a variable for storing the result
 
  result = num1 + num2; //adding the two numbers
 
  Serial.print("The result is: "); //text
  Serial.println(result); //result
 
  return;
}
 
void counterCode(double num1) //We count until a certain number and in every second we print a number
{
  for(int i = 0; i<num1; i++)
  {
    delay(1000); //wait a second
    Serial.print(i+1);
    Serial.println(" seconds elapsed");
  }
  Serial.println("Done!");
  return;
}
 
void sendFormattedData()// we create a random series of data which will be transferred to the serial terminal formatted
{
 
 
  if (enablerun == true)
  {
    Serial.print(cycles);  //we just print an increasing integer
 
    Serial.print('\t'); //separate it with a tab
 
    Serial.print(millis()); //we print some increasing number, such as the cpu's time
 
    Serial.print('\t'); //separation
 
    Serial.print(millis() * 3); //some number which increases proportional to the time
 
    Serial.println(); //new line
   
    //expected output format: 1 1000  3000
 
    delay(1000); //waiting a second
    cycles++; //increase the number of loops
  }  
 
}

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