resource temporarily unavailable on read() from linux device /dev/ttyS0 - c++

Question

I read all the solutions and test them. someone said used O_NDELAY and remove fnctl or the other said to use O_NONBLOCK and so on, but my problem does not solve.
I have nanopi neo and I want to use UART0. This is my code:
Main.cpp:
#include <QCoreApplication>
//#include "serialport.h"
#include "portserial.h"
#include <iostream>
#include <istream>
using namespace std;
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QString port;PortSerial *p;
cout<<"Enter tty:";
QTextStream s(stdin);
port = s.readLine();
p=new PortSerial(port,1);
if(p->openport(port)==1)
{
cout << "connected\n";
}
else
{
qDebug()<<"Not serial port : "<<port;
delete p;
}
return a.exec();
}
and portSerial.h and .cpp:
#ifndef PORTSERIAL_H
#define PORTSERIAL_H
#include <stdio.h> /* Standard input/output definitions */
#include <unistd.h> /* UNIX standard function definitions */
#include <fcntl.h> /* File control definitions */
#include "errno.h" /* Error number definitions */
#include "termio.h" /* POSIX terminal control definitions */
#include <stdlib.h>
#include "QDebug"
#define MAXDATASIZE 2048
#include <QByteArray>
#include <QThread>
#include <pthread.h>
class PortSerial:public QObject
{
Q_OBJECT
public:
QThread t;
// pthread_t pthrd;
int fd;
int status;
char * buffer;
char * buffertemp;
char buf2[MAXDATASIZE];
QString output;
QByteArray ba;
QByteArray batemp;
fd_set readfs;
timeval tv;
int n;
int devid;
bool wait;
PortSerial(QString port, int dev);
~PortSerial();
public slots:
int openport(QString port);
int init();
void closeport();
void readData();
void ifExist();
// int readifexist(char &tmp);
void writeData(QByteArray ba);
signals:
void readyread(QByteArray ba,int devids);
};
#endif // PORTSERIAL_H
and .cpp is:
#include "portserial.h"
PortSerial::PortSerial(QString port,int dev)
{
// qDebug()<<"Start the thread";
buffer = new char[1024];
devid=dev;
openport(port);
moveToThread(&t);
connect(&t, SIGNAL(started()), this, SLOT(ifExist()));
t.start();
}
PortSerial::~PortSerial()
{
closeport();
}
//____________________________
int PortSerial::openport(QString port)
{
fd=open(port.toStdString().c_str(),O_RDWR|O_NOCTTY|O_NDELAY/*O_NONBLOCK*/);//ARM
if (fd==-1)
{
return -1;//return open port error
}
else
{
// fcntl(fd,F_SETFL,O_NDELAY);
init();
return 1;
}
}
//-------------------------------------
void PortSerial::closeport()
{
qDebug()<<"Close with : " << close(fd);
}
//-------------------------------------
int PortSerial::init()
{
struct termios tty;
struct termios tty_old;
memset (&tty, 0, sizeof tty);
/* Error Handling */
if ( tcgetattr ( fd, &tty ) != 0 ) {
//qDebug() << "Error " << errno << " from tcgetattr: " << strerror(errno) << std::endl;
return -2;
}
/* Save old tty parameters */
tty_old = tty;
/* Set Baud Rate */
if(devid==1){//rfid
cfsetospeed (&tty, (speed_t)B9600);
cfsetispeed (&tty, (speed_t)B9600);
qDebug()<<"fd is : "<< fd<<" with this baud rate: 9600";
}
else{//fp
cfsetospeed (&tty, (speed_t)B115200);
cfsetispeed (&tty, (speed_t)B115200);
qDebug()<<"fd is : "<< fd<<" with this baud rate: 115200";
}
/* Setting other Port Stuff */
tty.c_cflag &= ~PARENB; // Make 8n1
tty.c_cflag &= ~CSTOPB;
tty.c_cflag &= ~CSIZE;
tty.c_cflag |= CS8;
tty.c_cflag &= ~CRTSCTS; // no flow control
tty.c_cc[VMIN] = 1; // read doesn't block
tty.c_cc[VTIME] = 5; // 0.5 seconds read timeout
tty.c_cflag |= CREAD | CLOCAL; // turn on READ & ignore ctrl lines
/* Make raw */
cfmakeraw(&tty);
/* Flush Port, then applies attributes */
tcflush( fd, TCIFLUSH );
if ( tcsetattr ( fd, TCSANOW, &tty ) != 0) {
//qDebug() << "Error " << errno << " from tcsetattr" << std::endl;
return -3;
}
return 1;
}
///new code
/// *******************************************************
///
///
/// *******************************************************
void PortSerial::readData()
{
buffer[0]=0;
usleep(20000);
int res = read(fd,buffer,2048);
if(res <=0)
qDebug() << strerror(errno) ;
if(res >0)
{
buffer[res]=0;
// batemp = QByteArray((char*)buffer, res);
batemp.append(QByteArray((char*)buffer, res));
// emit readyread(ba,devid);
// qDebug()<<"_____READ________\n"<<ba.toHex()<<"\n";
}
}
void PortSerial::ifExist()
{
int c=0;
while(1){
//set timeout for wait
tv.tv_sec = 0;
tv.tv_usec = 1000;
FD_ZERO(&readfs);
FD_SET(fd, &readfs);
n=select(fd+1, &readfs, NULL, NULL, &tv /* no timeout */);
if(n==1)
{
qDebug("##########################################################################reading");
readData();
}
else
{
if(batemp.length()>0){
qDebug()<<"batemp len is:"<<batemp.length();
emit readyread(batemp,devid);
qDebug()<<"\n________________________READ byte_____________________________\n"<<batemp.toHex()
<<"\nnon hex is: "<<batemp<<"\n";
batemp.clear();
}
}
}
}
///new code
/// *******************************************************
///
///
/// *******************************************************
//------------------------------------
void PortSerial::writeData(QByteArray ba)
{
int res=write(fd,ba,ba.length());
qDebug()<<"port write : "/*<<ba.toHex()*/<<"******* res is : "<<res;
}
When I give this serial port: /dev/ttyS0 to this, First read Null (0a03 in hex) and then just read this:
root#NanoPi-NEO:~# ./FPConsole -qws
Enter tty:/dev/ttyS0
fd is : 7 with this baud rate: 9600
fd is : 8 with this baud rate: 9600
connected
##########################################################################reading
batemp len is: 2
________________________READ byte_____________________________
"0a03"
non hex is: "
"
##########################################################################reading
Resource temporarily unavailable
How Can I solve this?To read the exact RFID card data and read it more than once without resource temporarily unavailable .