On Monday, August 8, 2016 at 11:32:36 PM UTC-7, William Hermans wrote: > > > https://briancode.wordpress.com/2015/01/06/working-with-pwm-on-a-beaglebone-black/ > > The sysfs pathing is a little different than explained on that blog( > changes in kernel 4.x ), but thats how PWM is supposed to work on the BBB. > > As for your error. It sounds as though the driver module is misconfigured > somehow in ARCH. I would suggest using Debian, getting to know the system > well, and then comparing with ARCH. Making sure whoever is responsible for > that ARCH image actually did things right. >
I figured out the issue. The driver was recently renamed from <address>.ehrpwm to <address.pwm but the corresponding DT clock entry in the kernel was not changed. The patch to fix this is not coming in until 4.8. However, picking up the patch [1] and rebuilding the kernel fixed the issue for me. [1] https://lkml.org/lkml/2016/3/7/648 Thanks > On Mon, Aug 8, 2016 at 10:16 PM, evilwulfie <[email protected] > <javascript:>> wrote: > >> most people here use debian. things just seem to work. ( thanks to Robert >> nelson.) >> try a debian image. >> >> >> >> On 8/8/2016 9:46 PM, [email protected] <javascript:> wrote: >> >> Hi, >> >> I am having trouble with BBB and using PWM. I am using Arch Linux and the >> following kernel "4.7.0-1-ARCH #1 Wed Jul 27 19:22:21 MDT 2016 armv7l >> GNU/Linux". >> >> When I try to enable PWM (echo "am33xx_pwm" > >> /sys/devices/platform/bone_capemgr/slots) I get the following error in >> kernel log: [ 72.786264] ehrpwm 48300200.pwm: Failed to get tbclk [ >> 72.791291] ehrpwm: probe of 48300200.pwm failed with error -2 Any idea what >> is wrong? Also, configuration of the PWM is very confusing. Can someone >> please explain how to configure PWM? For example I would like to use P9_16 >> as a PWM pin. What are the steps necessary to configure and use this pin as >> PWM? I assume I have to also use this overlay [1] but it seems to binds it >> to a "pwm_test" driver which does not exist in my kernel tree. However, >> even without this driver it seems like just inserting the "am33xx_pwm" >> overlay gives me option to "export" the pwm0 device: "echo 0 > >> /sys/class/pwm/pwmchip0/export". This gives me a folder >> "/sys/class/pwm/pwmchip0/pwm0/" >> that has nodes for duty_cycle, period, polarity, and enable..... [1] " >> https://github.com/beagleboard/devicetree-source/blob/master/arch/arm/boot/dts/bone_pwm_P9_16-00A0.dts"; >> >> Thanks! >> -- 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] >> <javascript:>. To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/98d065d0-7646-4b7c-bd9a-48029b100bb8%40googlegroups.com >> >> <https://groups.google.com/d/msgid/beagleboard/98d065d0-7646-4b7c-bd9a-48029b100bb8%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 [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/1102e4d8-8aea-ad00-f29d-46f876e9214b%40gmail.com >> >> <https://groups.google.com/d/msgid/beagleboard/1102e4d8-8aea-ad00-f29d-46f876e9214b%40gmail.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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/6dae88f3-1a56-4592-88a8-a228a81cd00b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
