Arduino serial data manipulation - Sensors Serial Data, Read and parse to variables

Question

I send 3 set of data from 3 sensors from Arduino 1 (router) to another Arduino(coordinator) to with wireless technology (xbee): On coordinator, I receive wireless data from this 3 sensors(from the router) perfectly. The data stream is something like this(each sensor data on its line):

22.5624728451
944
8523

I want to have these 3 values as 3 variables that get updated constantly and then pass these values on to the rest of the program to make something like print on LCD or something else:

temperature=22. 5624728451
gas=944
smoke=8523

Initially, I had only 2 sensors and I send the data of these 2 sensors something like this:
22.5624728451944(22.5624728451 – temperature, 944 - gas) and I received both of them on the same line and divided everything into two variables(with readString.substring() ) with the code below. But now I have 3 sensors and I receive data on a separate line because I don't know which is the length of each data string … And I can't use the same technique (sending only one string that contain all sensor data on the same line and then divide them)

My old code:

    #include <LiquidCrystal.h>
    LiquidCrystal lcd(12,11,10,9,8,7);  
    String temperature;
    String gas;
    String readString;

    void setup() {
    Serial.begin(9600);          
    lcd.begin(16, 2);                              
    }
    void loop() {
      while (Serial.available() > 0)                             
    {
    char IncomingData = Serial.read();                   
    readString += IncomingData ;       
    temperature = readString.substring(0, 13); //get the first 13 characters
    gas = readString.substring(13, 16); //get the last 3 characters 

    Serial.print(IncomingData);  //here I have my string: 20.1324325452924 wichs is updating properly when I have sensor values changes 

    // Process message when new line character is DatePrimite
    if (IncomingData == '\n')
    {
      Serial.println(temperature);
      lcd.setCursor(0,0);                              
      lcd.write("T:");
      lcd.print(temperature);               
     delay(500);
     temperature = "";                               // Clear DatePrimite buffer

     Serial.println(gaz);
     lcd.begin(16, 2);
     lcd.setCursor(0,1);                              
     lcd.write("G:");
     lcd.print(gas);
     delay(500);
     gaz = "";                                       // Clear DatePrimite buffer
     readString = "";
  }
}

}

All I want to do now is to assign a variable for every sensor data (3 lines – 3 variables for each line) updated constantly and then pass these values on to the rest of the program. Does anyone have any idea how to modify the code tO work in this situation? Thank you in advance!

Answer 1

I would recommend that you concatenate the values into the same line on the sending end and use a delimiter like a comma along with string.split() on the receiving end if you are committed to using string values. EDIT: It appears Arduino does not have the string.split() function. See this conversation for an example.

An alternative would be to set a standard byte length and send the numbers as binary instead of ASCII encoded strings representing numbers. See this post on the Arudino forum for a little background. I am recommending sending the number in raw byte notation rather than as ASCII characters. When you define a variable as in integer on the arduino it defaults to 16-bit signed integer value. A float is a 32-bit floating point number. If, for example, you send a float and two ints as binary values the float will always be the first 4 bytes, the first int, the next 2 and the last int the last 2. The order of the bytes (endianness, or most significant byte first (Big Endian, Motorolla style)/least significant bit first (Little Endian, Intel style)).