Using atof on a string

Projects Programming
1

Hi

I have incoming string from a sensor (Atlas Scientific)

#include <SoftwareSerial.h>                                                    //add the soft serial libray
#define rxpin 2                                                                //set the RX pin to pin 2
#define txpin 3                                                                //set the TX pin to pin 3


SoftwareSerial myserial(rxpin, txpin);                                         //enable the soft serial port


String inputstring = "";                                                       //a string to hold incoming data from the PC
String sensorstring = "";                                                      //a string to hold the data from the Atlas Scientific product
boolean input_stringcomplete = false;                                          //have we received all the data from the PC
boolean sensor_stringcomplete = false;                                         //have we received all the data from the Atlas Scientific product


  void setup(){                                                                //set up the hardware
     Serial.begin(38400);                                                      //set baud rate for the hardware serial port to 38400
     myserial.begin(38400);                                                    //set baud rate for software serial port to 38400
     inputstring.reserve(5);                                                   //set aside some bytes for receiving data from the PC
     sensorstring.reserve(30);                                                 //set aside some bytes for receiving data from Atlas Scientific product
     }
 
 
 
   void serialEvent() {                                                         //if the hardware serial port receives a char
               char inchar = (char)Serial.read();                               //get the char we just received
               inputstring += inchar;                                           //add it to the inputString
               if(inchar == '\r') {input_stringcomplete = true;}                //if the incoming character is a <CR>, set the flag
              }  
 
 
 
 void loop(){                                                                   //here we go....
     
  if (input_stringcomplete){                                                   //if a string from the PC has been recived in its entierty 
      myserial.print(inputstring);                                             //send that string to the Atlas Scientific product
      inputstring = "";                                                        //clear the string:
      input_stringcomplete = false;                                            //reset the flage used to tell if we have recived a completed string from the PC
      }
 

  while (myserial.available()) {                                               //while a char is holding in the serial buffer
         char inchar = (char)myserial.read();                                  //get the new char
         sensorstring += inchar;                                               //add it to the sensorString
         if (inchar == '\r') {sensor_stringcomplete = true;}                   //if the incoming character is a <CR>, set the flag
         }


   if (sensor_stringcomplete){                                                 //if a string from the Atlas Scientific product has been received in its entirety
       Serial.print(sensorstring);                                             //use the hardware serial port to send that data to the PC
       sensorstring = "";                                                      //clear the string:
       sensor_stringcomplete = false;                                          //reset the flag used to tell if we have received a completed string from the Atlas Scientific product
      }
}

The data that comes from the sensor is a string like "45.6723,9.0876,545.256 " and it represents "Total liters, Liter per minute, Liters per hour"
I want to take the "Total liters" value turn it into a float so I can send it through Modbus TCP into my HMI screen and display the value as a graph.
Then I want to take the "Liter per minute" value turn it into a float so I can send it through Modbus TCP into my HMI screen and display the value as a graph.
And at last take the " Liter per minute, Liters per hour" value turn it into a float so I can send it through Modbus TCP into my HMI screen and display the value as a graph.

I tried to use this code in my while loop

 while (myserial.available()) {                                               //while a char is holding in the serial buffer
       
         int i=0;  
        
         char inchar = (char)myserial.read();                                  //get the new char
         sensorstring += inchar;                                               //add it to the sensorString
         if (inchar == '\,')
           {
               valueone=atof(sensorstring.c_str());                   
            }
               
         if (inchar == '\r') {sensor_stringcomplete = true;}                   //if the incoming character is a <CR>, set the flag
         }

And I got the fist value XD...
But I have a trouble getting the other ones... :cold_sweat:

Can any one help me for a code to do this?
I have been trying to use the "strtok" command to split my string up, but no luck.

Regards
Steini

2

Try strtok() first to break out each number as a string:

http://www.cplusplus.com/reference/cstring/strtok/

then use atof() to finish the job.

3

Your data seems to be comma delimited, is there an end marker for the series of data packets before the next series is sent? Simple code that uses a comma as a delimiter.

//zoomkat 3-5-12 simple delimited ',' string  
//from serial port input (via serial monitor)
//and print result out serial port

String readString;

void setup() {
  Serial.begin(9600);
  Serial.println("serial delimit test 1.0"); // so I can keep track of what is loaded
}

void loop() {

  //expect a string like wer,qwe rty,123 456,hyre kjhg,
  //or like hello world,who are you?,bye!,
  
  if (Serial.available())  {
    char c = Serial.read();  //gets one byte from serial buffer
    if (c == ',') {
      //do stuff
      Serial.println(readString); //prints string to serial port out
      readString=""; //clears variable for new input      
     }  
    else {     
      readString += c; //makes the string readString
    }
  }
}