Capemgr .dtbo location

[matthew...@gmail.com]

I'm trying to decipher how the Adafruit_BBIO Python library does PWM, in preparation for supporting kernels 4.1+. The library currently loads a cape file of the name "bone_pwm_P9_21" or whatever pin number. I've looked in the /lib/firmware folder and there is no such .dtbo file.

The elinux wiki page on the topic (http://elinux.org/Capemgr) says that the capemgr checks in arch/arm/boot/dts/am335x-bone-common.dtsi for a corresponding .dtbo file, or /lib/firmware. My question is: how can I read that .dtsi file to know where it's getting the corresponding .dtbo?

[William Hermans]

Hi Matthew,

I'll propose a different approach. First, use universal IO to mux your pins for PWM. Then just use the PWM sysfs file system to deal with the rest.

So, I have not done this personally yet, but I know it's possible, as I've seen blog posts on it in the past. The universal io part I would probably need help from Charles as I've not that done with universal io either. But I suspect it's very simple.

If you have further question on the subject I can help guide you. As I'd really lie to see people getting away from Adafruits BBIO whihc seems to be abandon ware now days

On Tue, Jul 19, 2016 at 4:51 PM, <matthew...@gmail.com> wrote:

I'm trying to decipher how the Adafruit_BBIO Python library does PWM, in preparation for supporting kernels 4.1+. The library currently loads a cape file of the name "bone_pwm_P9_21" or whatever pin number. I've looked in the /lib/firmware folder and there is no such .dtbo file.

The elinux wiki page on the topic (http://elinux.org/Capemgr) says that the capemgr checks in  arch/arm/boot/dts/am335x-bone-common.dtsi for a corresponding .dtbo file, or /lib/firmware. My question is: how can I read that .dtsi file to know where it's getting the corresponding .dtbo?

--
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/20f03625-d376-4379-883c-712a95d1c676%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[William Hermans]

Here is one such good link that even discusses using universal io. https://briancode.wordpress.com/2015/01/06/working-with-pwm-on-a-beaglebone-black/

Just be aware that this blog post was written with kernel 3.8.x in mind. Some file paths have changed since then but is something that can be accounted for.