Am Donnerstag, den 28.05.2009, 11:09 +0200 schrieb Emmanuel Viollet: > Hi. > > Thanks for the answer. > > I tried "setserial /dev/ttyS1 low_latency" before launching my program, > but I didn't notice any difference. > I still have at least 20 ms latency before AND after transmission. > > Is the syntax correct? Am I using the command correctly? Am I supposed > to add something to my program in order to benefit from the low latency ? > > Regards, > yes, that looks correct. It shouldn't be necessary to add anything in your application. Have you verified that your serial IRQ is working?
-Erwin > > Erwin Authried a écrit : > > normally, there is a latency of ~5-10msec before characters are > > processed. This can be reduced with setserial, with the low_latency > > parameter. > > > > The maximum of 250msec that you mentioned seems very slow, however. Have > > you made sure that your serial driver uses interrupts, otherwise it may > > fall back to polling. > > > > -Erwin > > > > > > Am Donnerstag, den 28.05.2009, 09:27 +0200 schrieb Emmanuel Viollet: > > > >> Hi. > >> > >> I'm running uclinux 2.6.24.2-uc0 on an Olimex LPC2468 evaluation board > >> and have an issue with serial ports. > >> > >> I'm using the standard Linux serial functions (open(), write(), etc.), > >> and have discovered (after analysis with an oscilloscope) that the delay > >> between the write() function and the actual ouput on the serial port > >> varies between 20 and 250 ms. > >> I find this delay quite long. Is there anything I can do to force the > >> serial output as soon as I've put the data in the output buffer? > >> > >> Also, the tcdrain() function returns approx. 20ms AFTER the data has > >> finished being sent by the UART. Is there any way to reduce this delay? > >> > >> In advance, thanks. > >> > >> _______________________________________________ > >> uClinux-dev mailing list > >> [email protected] > >> http://mailman.uclinux.org/mailman/listinfo/uclinux-dev > >> This message was resent by [email protected] > >> To unsubscribe see: > >> http://mailman.uclinux.org/mailman/options/uclinux-dev > >> > > > _______________________________________________ > uClinux-dev mailing list > [email protected] > http://mailman.uclinux.org/mailman/listinfo/uclinux-dev > This message was resent by [email protected] > To unsubscribe see: > http://mailman.uclinux.org/mailman/options/uclinux-dev -- Dipl.-Ing. Erwin Authried Softwareentwicklung und Systemdesign _______________________________________________ uClinux-dev mailing list [email protected] http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by [email protected] To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
