Hi,
I am trying to get PWM to work on a Beagle Bone Black, 3.18.1 kernel. I
have am using Robert C Nelson's kernel and have managed to compile it. I
have also got Device trees to work in that I have a Makefile which creates
device trees and compiles them. (Uses cpp, then dtc).
The makefile emulates how the Device Tree is compiled using the
build_kermel.sh. So far so good. I got the SPI to work in the that I can
see the /dev/spidev1.0 devices. That was simple in that all I had to do was
to un-comment the include in the file.
What I am stuck on is how to get PWM's to work. If Robert or someone could
tell me how to set pin P8_13 to be a PWM using device trees using Kernel
3.18.1 that would be very helpful. Also some notes of what to look for in
/dev/ and /sys/devices would also be helpful. I see quite a few examples
for Kernel 3.8 where the CAPE managers are present, but I do not have a Cap
Manager operational in 3.18.1
I see in device tree source:
P8_13_pinmux {
compatible = "bone-pinmux-helper";
status = "okay";
pinctrl-names = "default", "gpio", "gpio_pu",
"gpio_pd", "pwm";
pinctrl-0 = <0x5a>;
pinctrl-1 = <0x5b>;
pinctrl-2 = <0x5c>;
pinctrl-3 = <0x5d>;
pinctrl-4 = <0x5e>;
};
So I think I should use pinctrl-4 somehow to get PWM. I think 0x5e means
therefore binary 01011110. But I think this means it is in mode 6 which is
a not a valid mode. So I have got the wrong end of the stick here a bit and
am misunderstanding something.
Also what else do I need to have to refer back to P8_13 and make that into
a Device in /dev like the SPI pins? What is the pinmuxhelper and how can I
use that? Should I be trying to use that?
Many thanks Mike.
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