Thanks for your answer. I'm used to program on processor without OS. I want try linux to use linux to have have LCD, ethernet, USB, ... , dirvers. I have to read message that comme on the CAN bus every 2ms. Then I have to show values on the LCD and transfers some message on the RS232. I need a timer to the check the reception of the messages. I seem it is difficult with linux. I will try with the RTAI.
regards Jean Nicollerat regards -----Original Message----- From: wd at denx.de [mailto:[EMAIL PROTECTED] Sent: Thursday, March 17, 2005 9:34 AM To: Jean Nicollerat MD Cc: linuxppc-embedded at ozlabs.org Subject: Re: RTC with TQM823L In message <HMECJAKDCPLOGPDHNAHECEKFCAAA.jean.nicollerat at microdev.ch> you wrote: > > I need to have an interrup every 10ms in my application running in linux. This is an oxymoron. Interrups are processed in kernel space, applications are running in userspace. You cannot process interrupts in aplication code. > I try to use the RTC modules but with the code : > > fd = open ("/dev/rtc", O_RDONLY); > > if (fd == -1) { > perror("/dev/rtc"); > } > /* Turn on update interrupts (one per second) */ You mentioned you wanted signals (not interrupts) every 10 millisec, not every second -- what exactly is it that you want? > retval = ioctl(fd, RTC_UIE_ON, 0); ... > ioctl : invalide argument # for then line :"retval = ioctl(fd, RTC_UIE_ON, > 0);" Which means that the driver does not support this ioctl. > Can somebody help ? why it is not working or a better way to get function > called each 10ms You can use setitimer. But be warned. Your requirement of having signals every 10 milliseconds means that there is a serious problem with your software design. You are doing someting really, really wrong. To me it sounds as if you try to implement your own timer based control loop in user space with an insane smapp period. This will never work reliably (as there is no guarantee that your tasks will be scheduled in time), and will waste a lot of CPU power. Never take existing software designs from other operating system environments and put them without thinking into a Unix environment. Often there are much better and more efficient approaches in Unix. Just in case you really must stick with that 10 millisecond raster: in this case you will probably have to use RTAI (especially on a resource-limted CPU like the 823). Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de The trouble with our times is that the future is not what it used to be. - Paul Valery
