Thank you TJF, I never would have known about that register if you hadn't mentioned it. One more question (see below):
On Sat, Apr 1, 2017 at 9:20 PM, TJF <jeli.freih...@gmail.com> wrote: > Am Samstag, 1. April 2017 22:18:30 UTC+2 schrieb Justin Pearson: >> >> Are you saying that the only way to get PWM in a 4.x kernel is by >> modifying am33xx-clocks.dtsi? >> > > No. The kernel driver should also work (untested). But in your case > (controlling the PWM subsystem by PRU code) you have to modify that file. > (Or you can develop a loadable kernel module that writes to the register.) > On the 3.18 kernel, I was able to control the PWM with the PRU without needing the PRU to initialize the PWM. The trick was to load the PWM capes "am33xx_pwm" and "bone_pwm_P8_34" before running the PRU code. (And also loading Derek's cape <https://github.com/derekmolloy/exploringBB/blob/master/chp13/overlay/EBB-PRU-Example.dts> to initialize the pruss.) Loading the capes causes some PWM kernel driver to initialize the PWM registers, I assume. Once that's done, the PRU just has to tweak a couple registers to change the duty cycle. Is this trick what you're referring to when you say "*The kernel driver should also work*"? Would this trick of pre-loading the capes also work in a 4.x kernel? Thanks for all your help! Justin > > >> Also, how can I verify whether the register is set correctly? >> > > The PRU cannot write to the Control Module registers, but it can read > them. Get a word from 0x44E10664 and pass it to the ARM code. Bits 0:2 must > be set to get output from all PWM subsystems. In your case bit 1 set is > sufficient to get ehrpwm1B working. > > Regards > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit https://groups.google.com/d/ > topic/beagleboard/LZhL4S9taic/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > beagleboard+unsubscr...@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/beagleboard/3041a94e-58ab-4c28-ad29-ad3a2b90315b%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/3041a94e-58ab-4c28-ad29-ad3a2b90315b%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- 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/CABCHBhJ_PNMAYB9qzijL1GT0iWWkSvSq6kriHdZojRmbrraYrw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
