while(counter<100){
sem.take()
size = rt_dev_write(fd, myString, strlen(myString));
sem.give()
if(size<0){
printf(MAIN_PREFIX "3 : error %s (write), %s\n", WRITE_FILE,
strerror(-size));
return size;
}
printf("%d\n",counter);
usleep(100000); //sleep a few millis
counter++;
}
There should be solutions to with a flag or similar which can tell
when rt_dev_write() actually is finished. Until then wait()/sleep()
would probabily be the best solution.
Are there suitable solutions where no polling is made and make me wait
until the data have been written out to rtser0?
/Bachman
On 13/09/2007, Eric Noulard <[EMAIL PROTECTED]> wrote:
> 2007/9/13, Bachman Kharazmi <[EMAIL PROTECTED]>:
> > Hi!
> > I try to print to serialport using rtdm according to:
> > http://pastebin.ca/695418
> >
> > But if I don't have sleep(1) only "hello " or similar is written to
> > the serialport.
> > But if I've sleep(1) "helloworld" is written every second as expected.
>
> I'm no xenomai expert but I think
> you shouldn't write to serial device in such a tight loop:
>
> while(counter <100){
> rt_dev_write(fd, myString, strlen(myString));
> printf("%d\n",counter);
> // sleep(1); WITHOUT THIS SLEEP helloworld is sent on serial once.
> counter++;
> }
>
> because you will certainly fills the send buffer without giving a chance
> to the drive to send more data than the one that fits in the buffer
> (this heavily depends wether if the device is opened in blocking
> or non-blocking mode)
>
> FIRST of ALL you should check the return value of your function call
>
> rt_dev_write should return either the number of written bytes
> http://www.xenomai.org/documentation/branches/v2.3.x/html/api/group__userapi.html#ge966625748b547779bb8c5385e7fb2aa
>
> or a negative error code:
> http://www.xenomai.org/documentation/branches/v2.3.x/html/api/group__rtserial.html
>
>
> > Is this some kind of limit how quickly I can write stuff on the rtser0?
>
> Yes there must be.
> Serial device are not as fast as any recent CPU.
> Beginning with the fact that you did configure the serial link at 115200 bauds
> it would'nt wise to try to feed at an "average" speed that exceed this number.
>
>
> > How do I handle this?
>
> Check the return value of your rt_dev_write calls :)
>
>
> --
> Erk
>
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