Linux C++ Serial Programming Not Working Why? - c++

Question

#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <errno.h>
#include <cerrno>
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fstream>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <cstdlib>
#include <ctime>
using namespace std;
typedef struct termios ComSet;
int main()
{
int acm=-1;
acm=open("/dev/ttyACM0",O_RDWR | O_NOCTTY);
if(acm == -1)
{
cout<<"Error Opening ttyACM0"<<endl;
exit(1);
}
else
{
cout<<"Preparing ttyACM0..."<<endl;
ComSet SerialSettings;
tcgetattr(acm, &SerialSettings);
cfsetispeed(&SerialSettings,B115200);
cfsetospeed(&SerialSettings,B115200);
/* 8N1 Mode */
SerialSettings.c_cflag &= ~PARENB;
SerialSettings.c_cflag &= ~CSTOPB;
SerialSettings.c_cflag &= ~CSIZE;
SerialSettings.c_cflag |= CS8;
SerialSettings.c_cflag &= ~CRTSCTS;
SerialSettings.c_cflag |= CREAD | CLOCAL;
SerialSettings.c_iflag &= ~(IXON | IXOFF | IXANY);
SerialSettings.c_iflag &=ICANON;
SerialSettings.c_iflag &= ~(ECHO | ECHOE | ISIG);
SerialSettings.c_oflag &= ~OPOST;
/* Setting Time outs */
SerialSettings.c_cc[VMIN] = 1;
SerialSettings.c_cc[VTIME] = 0;
if((tcsetattr(acm,TCSANOW,&SerialSettings)) != 0)
{
cout<< " ERROR ! in Setting attributes"<<endl;
}
else
{
cout<< "=======ttyACM0 Setting====="<<endl;
cout<<"BaudRate = 115200 StopBits = 1 Parity = none"<<endl;
cout<<"Reading ttyACM0... "<<endl;
char read_buffer[1024];
bzero(read_buffer,1024);
int read_bytes=0;
while(1)
{
write(acm,"Hello World !",13);
read_bytes=read(acm,&read_buffer,1024);
if(read_bytes>0)
{
cout<<read_buffer;
bzero(read_buffer,1024);
}
else
{
cout<<"No-Data"<<endl;
}
tcflush(acm, TCOFLUSH);
tcflush(acm, TCIFLUSH);
}
}
close(acm); /* Close the serial port */
}
return 0;
}
Why is this code not working ? i m trying to receive same message from the arduino but it will not work.it completely ignores write.i have also found that it works if i use cin.get() before write.
it works if i want to read from arduino only.
Here is my arduino code
String Input;
boolean done=false;
void setup()
{
Serial.begin(115200);
}
void loop()
{
Serial.println(GetSerial());
Input="";
}
String GetSerial()
{
done=false;
Input="";
while(!done)
{
while(Serial.available()>0)
{
Input=Serial.readStringUntil('\n'); //Block Reading
done=true;
}
}
return Input;
}
i want to receive whatever is sent on serial port as it is with as much less delay as possible