One PWM output pin initializes high while the other 2 initialize low

[Dave Littell]

Greetings,

Using SDK v3.1.1 I've configured 3 PWM outputs using the pwm0-2 modules via a DTS overlay.  After reset or power cycle (and prior to making any PWM driver calls), the pwm0 output at P1.15 starts off high while the remaining two outputs are low (P1.14 and P1.07).  My hardware requires that all the outputs start off low.  I've tried changing the polarity of pwm0 with no effect - P1.15 still starts off high.  How do I ensure that all the PWM outputs start off low after a reset or power cycle?

Here's the PWM portions of my DTS overlay:

/ {

	pwmheaters {
		compatible = "pwm-leds";

		pwm0_channel0: pwm0_channel0 {
			pwms = <&pwm0 0 PWM_MSEC(100) 0>;
		};

		pwm1_channel0: pwm1_channel0 {
			pwms = <&pwm1 0 PWM_MSEC(100) 0>;
		};

		pwm2_channel0: pwm2_channel0 {
			pwms = <&pwm2 0 PWM_MSEC(100) 0>;
		};
	};
	
};


&pwm0 {
	status = "okay";
	pinctrl-0 = <&pwm0_default>;
	/delete-property/ pinctrl-1;
	pinctrl-names = "default";
};


&pwm1 {
	status = "okay";
	pinctrl-0 = <&pwm1_default>;
	/delete-property/ pinctrl-1;
	pinctrl-names = "default";
};


&pwm2 {
	status = "okay";
	pinctrl-0 = <&pwm2_default>;
	/delete-property/ pinctrl-1;
	pinctrl-names = "default";
};


&pinctrl {

	pwm0_default: pwm0_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 1, 15)>;
		};
	};


	pwm1_default: pwm1_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 1, 14)>;
		};
	};


	pwm2_default: pwm2_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 1, 7)>;
		};
	};

};

Thanks,

Dave

[Kazi Afroza Sultana]

Hello,

Can you try this (using a “sleep” state with low-power-enable) for the pinctrl of pwm0?

&pinctrl {
    pwm0_default: pwm0_default {
        group1 {
            psels = <NRF_PSEL(PWM_OUT0, 1, 15)>;
        };
    };

    pwm0_sleep: pwm0_sleep {
        group1 {
            psels = <NRF_PSEL(PWM_OUT0, 1, 15)>;
            low-power-enable;
        };
    };
};

&pwm0 {
    status = "okay";
    pinctrl-0 = <&pwm0_default>;
    pinctrl-1 = <&pwm0_sleep>;
    pinctrl-names = "default", "sleep";
};

It may help to define low power state.

[Dave Littell]

Thanks, but explicitly getting rid of the "nordic,invert" with a "/delete-property/" fixed it.  Having to undo stuff like this from the DK DTS has wasted some significant time (and keeps popping up as we progress).  I'd request that you guys offer the option of starting with a clean DTS with none of the DK-specific stuff instead of forcing developers to create their own and spend time bludgeoning it into submission.  ;-)