SK-AM62: Configure PWM

Cherry Zhou

Part Number: SK-AM62

Hi team,

Refer https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/08_06_00_42/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/PWM.html to modify the device tree as follows:

mypwm {

pwm-3{
pwms = <&main_pwm3 0 50000 0>;
status = "okay";};
};

main_pwm3: dmtimer-main-pwm-3 {
pinctrl-0 = <&mytimer3_pins_default>;
pinctrl-names = "default";
compatible = "ti,omap-dmtimer-pwm";
#pwm-cells = <3>;
ti,timers = <&main_timer3>;
};

mytimer3_pins_default: mytimer3-pins-default {
pinctrl-single,pins = <
AM62X_IOPAD(0x01dc, PIN_OUTPUT, 2) /* (E15) MCAN0_RX.TIMER_IO3 */
>;
};

PWM1 file cannot be generated when echo 0 > /sys/class/pwm/pwmchip0/export is used. Also it cannot be generated when testing leds--led-0 of AM62 evaluation board. What could be the possible issue here?

Could you help look into this case? Thanks.

Best Regards,

Cherry

over 2 years ago

0 Nick Saulnier over 2 years ago

TI__Guru** 100740 points

Hello Cherry,

Please give me a couple of days to see if dmtimer PWM is even supported on AM62x SDK 8.6.

My understanding was that it was not, as per my guidance here: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1245532/am625-echo-0-export-but-got--sh-echo-write-error-device-or-resource-busy/4710112#4710112

However, it seems very clear that dmtimer PWM is supported in AM62x SDK 9.0 with the new devicetree file overlay k3-am625-sk-dmtimer-pwm.dtso, and both AM62x SDK 8.5 and 8.6 include a ti,omap-dmtimer-pwm node defined in k3-am62x-sk-common.dtsi. So I might have been wrong on that other thread.

Please ping the thread if I have not provided another response within a couple of days.

Regards,

Nick

0 Annie Liu over 2 years ago in reply to Nick Saulnier

TI__Genius 10295 points

Hi Nick,

Not just a dmtimer PWM problem. At present, the main problem is that the existing channels cannot be exported using export, as shown in the figure below. Is there a step where customer missed something?

reference link: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1250074/sk-am62-configure-pwm

The modification in the device tree is as follows:

&epwm0 {
pinctrl-names = "default";
pinctrl-0 = <&myepwm0_pins_default>;
status = "okay";
};

myepwm0_pins_default: myepwm0-pins-default {
pinctrl-single,pins = <
AM62X_IOPAD(0x01b4, A4, 2) /* (A13) SPI0_CS0.EHRPWM0_A */
AM62X_IOPAD(0x01b8, PIN_OUTPUT, 2) /* (C13) SPI0_CS1.EHRPWM0_B */
>;
};

0 Nick Saulnier over 2 years ago in reply to Annie Liu

TI__Guru** 100740 points

Hello Annie & Cherry,

timer as pwm

Just wanted to confirm that my guidance about DM Timer as PWM on the previous thread was NOT correct.

Support for DM timer as PWM was added starting in AM62x SDK 8.5.

the export behavior

I will spend some more time looking at this early next week. Please ping the thread if I have not replied within a couple more business days.

Regards,

Nick

0 Annie Liu over 2 years ago in reply to Nick Saulnier

TI__Genius 10295 points

timer as pwm

Does it support the same as LEDs, operate the TIME timer, and use it as PWM output?

the export behavior

The issue was resolved.

Regards,

Annie

0 Nick Saulnier over 2 years ago in reply to Annie Liu

TI__Guru** 100740 points

Hello Annie,

Glad to hear that the export behavior was resolved!

I do not understand the question under "timer as pwm". Can you please reword the question for me?

Regards,

Nick

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SK-AM62: Configure PWM