LED PWM

[umeshdj]

How many PWM channels I can define such as the following for nRF52832?

pwmleds {
compatible = "pwm-leds";
pwm_led0: pwm_led_0 {
pwms = <&pwm0 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
};

};

in DTSI file I will have corresponding pwm_default and pwm_sleep.

I want to drive six pwm LEDs.

[Elfving]

Hello,

The nRF52832 comes with 3 PWM modules with 4 channels.

So you can get a total of 12 PWM channels, that can drive 12 assigned GPIOs. Though you only have independent frequency control in these 3 PWM modules.

So driving 6 PWM LEDs is possible, the question is how you want to do it. Do any particular ones need a different frequency?

Regards,

Elfving

[umeshdj]

Same frequency is required for all six channels

[umeshdj]

Hello Elfving

I need 6 PWMs for driving LEDs with the same frequency.

Regards

Umesh

[Elfving]

Hi Umesh, and sorry about the delay.

umeshdj said:

Same frequency is required for all six channels

That makes it easier.

Have a look at this dts overlay file. Here I am enabling pwm1, and adding GPIO 22 and 23. Note that pwm_led_4 uses channel 1.

// To get started, press Ctrl+Space to bring up the completion menu and view the available nodes.

// You can also use the buttons in the sidebar to perform actions on nodes.
// Actions currently available include:

// * Enabling / disabling the node
// * Adding the bus to a bus
// * Removing the node
// * Connecting ADC channels

// For more help, browse the DeviceTree documentation at https://docs.zephyrproject.org/latest/guides/dts/index.html
// You can also visit the nRF DeviceTree extension documentation at https://nrfconnect.github.io/vscode-nrf-connect/devicetree/nrfdevicetree.html
// To get started, press Ctrl+Space to bring up the completion menu and view the available nodes.

// You can also use the buttons in the sidebar to perform actions on nodes.
// Actions currently available include:

// * Enabling / disabling the node
// * Adding the bus to a bus
// * Removing the node
// * Connecting ADC channels

// For more help, browse the DeviceTree documentation at https://docs.zephyrproject.org/latest/guides/dts/index.html
// You can also visit the nRF DeviceTree extension documentation at https://nrfconnect.github.io/vscode-nrf-connect/devicetree/nrfdevicetree.html
&pinctrl {
    pwm0_default: pwm0_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 17)>,
                    <NRF_PSEL(PWM_OUT1, 0, 18)>,
                    <NRF_PSEL(PWM_OUT2, 0, 19)>,
                    <NRF_PSEL(PWM_OUT3, 0, 20)>;


			nordic,invert;
		};
	};

	pwm0_sleep: pwm0_sleep {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 17)>,
                    <NRF_PSEL(PWM_OUT1, 0, 18)>,
                    <NRF_PSEL(PWM_OUT2, 0, 19)>,
                    <NRF_PSEL(PWM_OUT3, 0, 20)>;

			low-power-enable;
		};
	};
	pwm1_default: pwm1_default {
		group1 {
			psels = 
					//for additional module
					<NRF_PSEL(PWM_OUT1, 0, 22)>,
					<NRF_PSEL(PWM_OUT2, 0, 23)>;

			nordic,invert;
		};
	};

	pwm1_sleep: pwm1_sleep {
		group1 {
			psels = 
					//for additional module
					<NRF_PSEL(PWM_OUT1, 0, 22)>,
					<NRF_PSEL(PWM_OUT2, 0, 23)>;
			low-power-enable;
		};
	};
};
&pwm1 {
	status = "okay";
	pinctrl-0 = <&pwm1_default>;
	pinctrl-1 = <&pwm1_sleep>;
	pinctrl-names = "default", "sleep";
};

/{
	pwmleds {
		compatible = "pwm-leds";
		pwm_led0: pwm_led_0 {
			pwms = <&pwm0 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
        pwm_led1: pwm_led_1 {
			pwms = <&pwm0 1 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
        pwm_led2: pwm_led_2 {
			pwms = <&pwm0 2 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
        pwm_led3: pwm_led_3 {
			pwms = <&pwm0 3 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		

		pwm_led4: pwm_led_4 {
			pwms = <&pwm1 1 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
		pwm_led5: pwm_led_5 {
			pwms = <&pwm1 2 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
		};
        
		status = "okay";
		
	};
};

I just tried this overlay along with the zephyr led pwm sample and got 6 leds to use pwm on the 52dk.

Regards,

Elfving