PWM in Wandboard Quad(i.MX6q)

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PWM in Wandboard Quad(i.MX6q)

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mustafabakircio
Contributor IV

Hi ;

I have a problem about to generate pwm in  Wandboard Quad , I generated the sdcard image with yocto project  but the pwm 's are isolated for backlight and other thing . But the 2 of them are not used , in my case , I can't  export  the two pwm pins with my kernel 

this is my kernel and linux versions  can be seen at .png images , I couldnt find any solution for these .

Do you have any idea about how to solve this problem ?

Thanks ...

6 Replies

529 Views
vinodmaverickr0
Contributor IV

Hi Mustafa,

sorry; But I did not get what you exactly want to do. If you are talking about PWM pins functionalities; so that should be already taken care in your device tree. And you can export these pins like as:

root@mx6qd:~# echo 0 > /sys/class/pwm/pwmchip1/export

root@mx6qd:~#cat /sys/class/pwm/pwmchip1/pwm0/*

Same way you can enable pin, set period and duty cycle.

529 Views
mustafabakircio
Contributor IV

Hi vinod kumar ;

I'm sorry for my late reply ,  yes your right about that I found out about a few days ago.

In my device tree these pwm's not enabled but I figure out how I can do .

Can I ask you something more ?

Can I make port mapping thereby changing the port output in the imx6qdl.dtsi or with imx6qdl-wandboard.dtsi ? Is it possible

Thanks for your interest ..

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vinodmaverickr0
Contributor IV

Hi Mustafa,

Can u pls elaborate more that what you mean by port mapping? Do you mean that use the existing pwm functionalities like if backlight is currently using the pwm0 and you want to use the pwm2 for backlight.

Thanks,

Vinod. 

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529 Views
mustafabakircio
Contributor IV

Hi vinod kumar,

For example I want the use GPIO3_12 OR  GPIO3_27  as a pwm pins . Is this possible ?

Thanks..

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vinodmaverickr0
Contributor IV

Hi Mustaffa,

PWM is nothing but just a toggling of a GPIO pin. Yes you can any GPIO pin for PWM purpose which is basically called as software PWM.

But there is always one thing which you need to consider that what is scope of (requirement) work. If you need very precise result then I will suggest you to use only hardware PWM. 

In the dtsi for every PWM there will be pin muxing so you can select accordingly.

 I am just explaining example for PWM1 pin selection.

Based on the Mainline line kernel; below are the possible pins and their muxing for PWM1

MX6QDL_PAD_GPIO_9__PWM1_OUT   

MX6QDL_PAD_SD1_DAT3__PWM1_OUT

MX6QDL_PAD_DISP0_DAT8__PWM1_OUT

Thanks,

vinod

529 Views
mustafabakircio
Contributor IV

Thank you for your help vinodcherry

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