Linux/PROCESSOR-SDK-AM335X: am335x pwm

Ahn

Intellectual 1000 points

Part Number: PROCESSOR-SDK-AM335X

Tool/software: Linux

Hi,

Does the am335x support one pwm output?

I set the device tree as below.

ehrpwm2_pins: ehrpwm2_pins {
  pinctrl-single,pins = <
   0xa0 ( PIN_OUTPUT | MUX_MODE3 ) /* (R1) lcd_data0.ehrpwm2A */
  >;
};

But there is no file in /sys/class/pwm.

my environment:

LINUX : linux-3.14.26-g2489c02

KERNEL CONFIG : CONFIG_PWM_TIECAP=y
CONFIG_PWM_TIEHRPWM=y

ps. reference site :

http://processors.wiki.ti.com/index.php/AM335x_PWM_Driver's_Guide

http://processors.wiki.ti.com/index.php/Linux_Core_PWM_User's_Guide

over 8 years ago

0 Yordan Kovachev over 8 years ago

TI__Guru**** 161600 points

Hi,

Do you have the &ehrpwm2 dts nodes, can you share them? Adding only the pinctr settings is not enough.

Best Regards,
Yordan

0 Ahn over 8 years ago in reply to Yordan Kovachev

Intellectual 1000 points

Hi,
I don't have the &ehrpwm2 dts nodes.
I want to control the buzzer with pwm.
How do I add the &ehrpwm2 nodes?

0 Yordan Kovachev over 8 years ago in reply to Ahn

TI__Guru**** 161600 points

Hi,

You need to add something like:

&ehrpwm2 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <& ehrpwm2_pins>;
};

Best Regards,
Yordan

0 Ahn over 8 years ago in reply to Yordan Kovachev

Intellectual 1000 points

Hi,
I modified the device tree as follows.

&am33xx_pinmux {
ehrpwm2_pins: ehrpwm2_pins {
pinctrl-single,pins = <
0xa0 ( PIN_OUTPUT | MUX_MODE3 ) /* (R1) lcd_data0.ehrpwm2A */
>;
};
};

&ehrpwm2 {
pinctrl-names = "default";
pinctrl-0 = <&ehrpwm2_pins>;

status = "okay";
};

However, there is still no file in /sys/class/pwm.

0 Ahn over 8 years ago in reply to Ahn

Intellectual 1000 points

Hi,
There was a problem with the device tree configuration.

The device is recognized when it is modified as follows.

&epwmss2 {
status = "okay";
ehrpwm2: ehrpwm@48304200 {
pinctrl-names = "default";
pinctrl-0 = <&ehrpwm2_pins>;

status = "okay";
};
};

# ls /sys/class/pwm/
pwmchip0

Is this right?

How to control the buzzer?

0 Yordan Kovachev over 8 years ago in reply to Ahn

TI__Guru**** 161600 points

Yes, this is correct.

You can use the sysfs entries to control the pwm output. See the bellow guide:
processors.wiki.ti.com/.../AM335x_PWM_Driver's_Guide

Best Regards,
Yordan

0 Ahn over 8 years ago in reply to Yordan Kovachev

Intellectual 1000 points

Hi,
pwm device is different.

ls /sys/class/pwm/
pwmchip0

I checked the sound from the buzzer by referring to the guide below.
processors.wiki.ti.com/.../Linux_Core_PWM_User's_Guide

But, I can't set the polarity.
# echo 1 > /sys/class/pwm/pwmchip0/pwm0/polarity
sh: echo: write error: Invalid argument

And, How to play the melody?
Do you have a guide document?

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Linux/PROCESSOR-SDK-AM335X: am335x pwm