PWM backlight adjust using GPIO to set, device tree configuration

Paul Smith3

Other Parts Discussed in Thread: AM3358

I am using a BeagleBone Black board with the Sitara AM3358 running Linux. I am trying to get pin C15 as PWM output to adjust a display backlight. I want to use two GPIO pins as "brightness increase" and "brightness decrease" buttons. Is it possible to pipe those together into the PWM output using the device tree? What would the device tree look like for this configuration?

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi Paul,

I will forward this to the SW team.

0 Brad Griffis over 10 years ago in reply to Biser Gatchev-XID

TI__Guru*** 125430 points

You can't setup constructs like you describe (i.e. you can't "pipe" within the device tree). You would need to write code to "glue" together the GPIOs and the PWM. The most efficient implementation is probably to write your own driver that is just a layer on top of the other drivers. Or alternatively you could do this all from user space along the lines of this thread: stackoverflow.com/.../interrupt-handling-and-user-space-notification

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PWM backlight adjust using GPIO to set, device tree configuration