RE: Getting prescalar issue when I try to run PWM example with a period of 9975ms and pulse of 25ms

Nathan93 — Thu, 20 Feb 2025 11:59:53 GMT

I have solved this.

This Discussion : PWM in nrf5340 - blinky example fails to compile with SDK 2.7.0

Mentions that the default pwm node is software emulated and has a limitation of 262ms [PERIOD]. Thus we need to use the SW_PWM node.

The only changes required are in the overlay file

/ {
	pwmleds {
		compatible = "pwm-leds";
		status = "okay";

		red_pwm_led: red_pwm_led {
			pwms = <&sw_pwm 0 PWM_MSEC(100) PWM_POLARITY_INVERTED>; // This is P0.13
			label = "RED PWM LED";
		};

		green_pwm_led: green_pwm_led {
			pwms = <&sw_pwm 1 PWM_MSEC(100) PWM_POLARITY_INVERTED>; // This is P0.14
			label = "GREEN PWM LED";
		};

		blue_pwm_led: blue_pwm_led {
			pwms = <&sw_pwm 2 PWM_MSEC(100) PWM_POLARITY_INVERTED>; //This is P0.15
			label = "BLUE PWM LED";
		};
	};

    aliases {
		red-pwm-led = &red_pwm_led;
		green-pwm-led = &green_pwm_led;
		blue-pwm-led = &blue_pwm_led;
		swpwm = &sw_pwm;
	};
};

&pwm0 {
	status = "okay";
};

&sw_pwm {
	status = "okay";
	channel-gpios = <&gpio1 15 PWM_POLARITY_INVERTED>,
					<&gpio1 14 PWM_POLARITY_INVERTED>,
					<&gpio1 13 PWM_POLARITY_INVERTED>;
};

It works as expected and the prescalar issue is no longer observed.