You are correct that this application does not need to know the actual real time but only the relative (elapsed) time since the subroutine began. I'm familiar with clock_gettime but didn't think it could give me subsecond information. I'll explore it!
Thanks,! Walter On Wednesday, February 17, 2021 at 12:42:35 PM UTC-5 [email protected] wrote: > Hi Walter, > > I don't think you need an RTC for relative time. clock_gettime should do > the job (https://linux.die.net/man/3/clock_gettime) > There are also more intuitive ways to manipulate timespec structs in the > RCL (http://strawsondesign.com/docs/librobotcontrol/group__time.html). > > Best, > Michele > > On Wed, Feb 17, 2021 at 6:25 PM Walter Cromer <[email protected]> > wrote: > >> I really don't need ns. The valve 'on time' is going to be in the range >> of 500 ms to 2 seconds probably. >> >> I will review the PRUCookbook! Thanks! >> >> Walter >> On Wednesday, February 17, 2021 at 10:10:53 AM UTC-5 Mark A. Yoder wrote: >> >>> The PRUs can give you 10's of ns timing, which is more than good enough >>> for milliseconds, but might be over kill. >>> >>> I'd think using C on the ARM processor should be fast enough. I'd use >>> gpiod[1]. >>> >>> If you really want the ns timing of the PRUs, check out the PRU >>> Cookbook[2] >>> >>> --Mark >>> >>> [1] https://github.com/starnight/libgpiod-example >>> [2] https://github.com/MarkAYoder/PRUCookbook >>> >>> On Tuesday, February 16, 2021 at 10:51:11 AM UTC-5 [email protected] >>> wrote: >>> >>>> Depending on how precise you need to be, I would go for the PRU-ICSS. >>>> They can control the GPIOs pretty easily. >>>> >>>> Le mardi 16 février 2021 à 10:03:47 UTC-5, [email protected] >>>> a écrit : >>>> >>>>> I have a BBB Wireless running Linux beaglebone 4.14.108-ti-r106 #1 SMP >>>>> PREEMPT Fri May 24 22:12:34 UTC 2019 armv7l GNU/Linux >>>>> >>>>> I am writing in C. >>>>> >>>>> I turn a valve on and then need to read some sensors for N >>>>> milliseconds and then turn the valve off. >>>>> >>>>> What's the best way to read milliseconds on the BBBw? I don't have a >>>>> RTC on this particular unit but could add one using I2C. I have an >>>>> Adafruit 4282 with a DS3231 RTC on it on another BBBw that I could use >>>>> temporarily to prove it works. What other options are available? >>>>> >>>>> >>>>> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/fc16c0ce-4895-4bfd-93a4-245fe6b0d59cn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/beagleboard/fc16c0ce-4895-4bfd-93a4-245fe6b0d59cn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/2ee9976d-daf9-479c-b8a2-e17ef0c75cbbn%40googlegroups.com.
