Serial communication between c++ and arduino

Question

i need communicate with the arduino by using C++,i have tried this code for c++:

#include <iostream>
#include <fstream>
#include <stdio.h>
using namespace std;

int j=5;
main()
{
 fstream arduino;
 arduino.open("/dev/ttyACM0",ios::in | ios::out);
 //Opening device file

 if(!arduino)
   cout<<"error";
 arduino<<2;
 arduino.clear();
 arduino>> j;
 cout <<j;
 arduino.close();
 return 0;
}

Arduino code:

      int p;
      void setup() 
      {
          pinMode(13,OUTPUT);
          Serial.begin(9600);
       }

       void loop() 
       {
           if(Serial.available())
           {
               p=Serial.read();
               if(p!=-1)
               {
                   Serial.write(1);
                   digitalWrite(13,HIGH);
                   delay(5000);
                }   
            }
            else
            {
                digitalWrite(13,LOW);
                delay(1000);
            } 
        }

So according to this code when ever c++ code runs the led of pin 13 on arduino sould glow for 5 seconds and cout should print 1. But instead the led is not glowing and cout is printing 5 which(see that initially j=5).I am using this program to test serial communication between c++ and arduino. But I don't know what's happening.Also do we require any any special library for serial communication? Is my code alright? Please help me out.

@MANDY: Make sure you are configuring the right baud rate, parity, flow control, etc. before running the C++ program. For example, the stty utility can help with this. — Ben Voigt

Paulo1205 Paulo1205 · Accepted Answer · 2016-06-01T13:33:38

If j keeps its old value, it is likely that the attempt to read it is failing. Try checking the stream state, and checking for possible error conditions. For example:

if(arduino >> j)
    cout << "Value received: " << j << '\n';
else if(arduino.eof())
    cerr << "Premature EOF.\n";
else if(arduino.bad())
    cerr << "Attempt to read from device failed.\n";
else
    cerr << "Logical I/O error.\n";

Serial communication between c++ and arduino

1 Answers