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I am creating a simple application in which i will open a serial port and configure it and make two threads one is reader thread and second is writer thread. writer thread will write on serial port and reader thread will read this data.
I have done with opening and configuring the serial port :cool:now how a thread can write and read data from serial port; please help me out on this issue.:)
On what operating system?
On what hardware?
the operating sytem is linux(ubuntu). kernel version 2.6.38-rc4.i am reading and writing on tty0 port.
i think hardware shouldn't matter.
i have done it already...now all i have to do is create two threads one is reader thread and another writer thread, reader will read data on serial port written by the writer; actually i am not getting the concept how a thread can write data.please give some example.Quote:
Originally Posted by Mr.777
Try using
Code:Log(char* s); // prints out a log message
e.g.
Log("Thread writing...");
Output:Thread writing...
Erm, forget all about threads for the moment, and see how you get on with reading/writing the serial port using normal sequential code.
Threads are just a distraction until you can manage this simpler step.
First, you need to inherit your class from QThread class.
Then declare a pointer of type QTcpSocket...
And then use like..
Code:Suppose,
class abc :public QThread{
private:
QTcpSocket * p;
public:
void write_Thread(QString writing_Data);
};
void abc::write_Thread(QString writing_Data){
p->write(writing_Data.toAscii());
}
I'm waiting till he discovers the output on a serial port is not connected to the inputs... You can't write "hello" then read it back... It won't be there.Quote:
Originally Posted by Salem
He needs a "loopback" plug if he intends to send and recieve through the port on the same machine.
My code look like this after opening and configuring the baud rates of the portsActually i have to create this application with threads only.Without threads i know how to read and write directly on a serial port but after creating thread that thread should write i want the concept or code for this in which a thread read the data written by another thread.Code:#include<stdio.h> // Standard Input/output definations
#include<unistd.h> // UNIX standard function definations
#include<fcntl.h> // File control definations
#include<termios.h>// POSIX terminal control definations
#include<pthread.h>
int open_port(void)
{
int fildes;//File descriptor
fildes=open("/dev/tty0",O_RDWR | O_NOCTTY);
if(fildes==-1)
printf("\nUnable to open port!\n");
else
{
fcntl(fildes,F_SETFL,0);//Manipulate file descriptor,F_SETFL will return the value of flag
printf("\n**PORT IS OPEN**\n\n");
}
}
int config_port(int fildes)
{
struct termios termios_p;
cfsetispeed(&termios_p,B38400);//Setting output baud rate
cfsetospeed(&termios_p,B38400);//Setting input baud rate
tcsetattr(fildes,TCSANOW,&termios_p);
return (fildes);
}
int main()
{
int fildes=open_port();
config_port(fildes);
}
Don't you really think, you should return some value that should be used by fildes in main()?Code:int open_port(void)
{
int fildes;//File descriptor
fildes=open("/dev/tty0",O_RDWR | O_NOCTTY);
if(fildes==-1)
printf("\nUnable to open port!\n");
else
{
fcntl(fildes,F_SETFL,0);//Manipulate file descriptor,F_SETFL will return the value of flag
printf("\n**PORT IS OPEN**\n\n");
}
}
ya i will return it but this code is running,i will return the value once it is completed after writing code for creating threads and reading and writing data from serial port. Now please help me out i am in the middle of this application.Quote:
Don't you really think, you should return some value that should be used by fildes in main()?
Didn't you read my above posts in which i told you to write with threads????
Try that and tell....
where have you created the thread and how will it read the tty0 port??Quote:
Originally Posted by Mr.777
I think the more suitable approach will be creating a thread with posix library as pthread_create and in the start_routine we can give the read or write function which will read or write the serial port.Can we do it?
1
2
The code above uses the WaitForSingleObject function with a time-out value of INFINITE, this causes the WaitForSingleObject function to wait for long until the operation is completed and this can make the thread appear to be "hung" when the write operation is simply taking a long time to complete or flow control has blocked the transmission.Code:BOOL WriteABuffer(char * lpBuf, DWORD dwToWrite)
{
OVERLAPPED osWrite = {0};
DWORD dwWritten;
DWORD dwRes;
BOOL fRes;
// Create this <strong class="highlight">write</strong> operation's OVERLAPPED structure's hEvent.
osWrite.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
if (osWrite.hEvent == NULL)
// error creating overlapped event handle
return FALSE;
// Issue <strong class="highlight">write</strong>.
if (!WriteFile(hComm, lpBuf, dwToWrite, &dwWritten, &osWrite)) {
if (GetLastError() != ERROR_IO_PENDING) {
// WriteFile failed, but isn't delayed. Report error and abort.
fRes = FALSE;
}
else
// <strong class="highlight">Write</strong> is pending.
dwRes = WaitForSingleObject(osWrite.hEvent, INFINITE);
switch(dwRes)
{
// OVERLAPPED structure's event has been signaled.
case WAIT_OBJECT_0:
if (!GetOverlappedResult(hComm, &osWrite, &dwWritten, FALSE))
fRes = FALSE;
else
// <strong class="highlight">Write</strong> operation completed successfully.
fRes = TRUE;
break;
default:
// An error has occurred <strong class="highlight"><vb_highlight>in</strong></vb_highlight> WaitForSingleObject.
// This usually indicates a problem with the
// OVERLAPPED structure's event handle.
fRes = FALSE;
break;
}
}
}
else
// WriteFile completed immediately.
fRes = TRUE;
CloseHandle(osWrite.hEvent);
return fRes;
}
Read the given links (1,2)