Yes, but the hardware on the am335x can toggle multiple pins on the same chip in the same clock cycle. Seems like the software should be able to support it.
On Monday, August 10, 2020 at 10:20:10 AM UTC-4 evilw...@gmail.com wrote: > software takes time to execute. > > > On 8/10/2020 7:09 AM, Mark A. Yoder wrote: > > I'm starting to play with gpiod on a Beaglebone Black. One of the > advantages of gpiod is you can toggle multiple pins on the same chip all at > once. > So I try: > while true; do > gpioset 1 18=0 19=0 > gpioset 1 18=1 19=1 > done > > This is toggling pins P9_14 and P9_16. I expect to see the two pins > toggle on at the same time, but what I get is > a 4 microsecond delay from P9_14 switching and P9_16 switching. > > *Should there be such a long delay? * I'd expect the two to switch at the > same time (which is what happens when toggle pins via the PRU). > > I do the same experiment with python and I see a 70 us delay. > > --Mark > On Friday, March 27, 2020 at 3:58:21 PM UTC-4 Drew Fustini wrote: > >> On Fri, Mar 27, 2020 at 8:45 PM John Allwine <jo...@allwinedesigns.com> >> wrote: >> > >> > I don't intend to toggle a GPIO as fast as possible (except to test), >> but from a performance standpoint that demonstration seemed to indicate >> that there are issues with sysfs. Hopefully, libgpiod will prove to be >> better! >> >> Bartosz explains the differences and improvements that new gpiod >> interface provides in this talk: >> https://www.youtube.com/watch?v=cdTLewJCL1Y >> >> Essentially, if you need read or set multiple lines, it is faster. >> Also, it has an improved way to read events as well. >> >> Slides if you prefer over video: >> >> https://ostconf.com/system/attachments/files/000/001/532/original/Linux_Piter_2018_-_New_GPIO_interface_for_linux_userspace.pdf?1541021776 >> >> > -- > 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 beagleboard...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/16a18eef-a649-46d9-b126-f774a8eb1522n%40googlegroups.com > > <https://groups.google.com/d/msgid/beagleboard/16a18eef-a649-46d9-b126-f774a8eb1522n%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 beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/2a0cf82e-d223-4cfe-a623-27687edc3b4bn%40googlegroups.com.
