RE: I'm trying to control the brightness of the LEDs of my dev kit with the buttons

Elfving — Fri, 20 May 2022 10:28:35 GMT

No problem at all!

[quote user="Bastien"]It might be useful to include some informations about the device tree in the sample since only one LEDs is configured as pwm. [/quote]

That is a good point, I will pass that on to the relevant team.

Regards,

Elfving

RE: I'm trying to control the brightness of the LEDs of my dev kit with the buttons

Bastien — Fri, 20 May 2022 09:49:32 GMT

Hi, thank you very much for your help, your explanations were very clear. Now that I understand how the device tree works, everything is much easier ! It might be useful to include some informations about the device tree in the sample since only one LEDs is configured as pwm.

Thank you for your time,

Kind regards,

Bastien

RE: I'm trying to control the brightness of the LEDs of my dev kit with the buttons

Elfving — Fri, 20 May 2022 09:27:05 GMT

Hello Bastien, sorry about the wait.

And no worries about the questions, everything is allowed here.

[quote user=""]the “led_set_brightness” function doesn’t seem to use gpios like the on/off function does. And also, I don’t understand what this part means (the #defines are different from the way I used them in the first program :[/quote]

The led_set_brightness function uses all the available pwm-leds as a node, not a specific one. When it comes to the rest of the defines:

LOG_MODULE_REGISTER is only about logging, and not too relevant for this. For more info on logging see here.

#if DT_NODE_HAS_STATUS(DT_INST(0, pwm_leds), okay)
#define LED_PWM_NODE_ID		DT_INST(0, pwm_leds)
#define LED_PWM_DEV_NAME	DEVICE_DT_NAME(LED_PWM_NODE_ID)
#else
#error "No LED PWM device found"
#endif

The above defines adds all the pwm-led that have an "okay" status to the pwm-leds node.

#define LED_PWM_LABEL(led_node_id) DT_PROP_OR(led_node_id, label, NULL),

const char *led_label[] = {
	DT_FOREACH_CHILD(LED_PWM_NODE_ID, LED_PWM_LABEL)
};

This adds all the pwm-led nodes to the led_label list.

Note that you got the led_pwm sample (the second code snippet you provided) to work with only one LED, but the code is set to use all pwm-leds with an "okay" status. You can confirm that led1 is the only one set by taking a look at the .dts file of the board. If you add the code below to an overlay file (ie. nrf52840dk_nrf52840.overlay) you will see that all 4 of the LEDs are being used.

/ {
    pwmleds {
        compatible = "pwm-leds";
        pwm_led0: pwm_led_0 {
            pwms = < &pwm0 13 >;
        };
        pwm_led1: pwm_led_1 {
            pwms = < &pwm1 14 >;
        };	
        pwm_led2: pwm_led_2 {
            pwms = < &pwm2 15 >;
        };	
        pwm_led3: pwm_led_3 {
            pwms = < &pwm3 16 >;
            
        };	
    };
};
&pwm0 {
    ch0-pin = <13>;
    ch0-inverted;
    status= "okay";
};
&pwm1 {
    ch0-pin = <14>;
    ch0-inverted;
    status= "okay";
};
&pwm2 {
    ch0-pin = <15>;
    ch0-inverted;
    status= "okay";
};
&pwm3 {
    ch0-pin = <16>;
    ch0-inverted;
    status= "okay";
};

[quote user=""]I have now idea how considering that the “led_set_brightness” function[/quote]

To change the brightness I would stick with the led_set_brightness() function. For more info on how to use it see here.

Let me know if there is anything that I haven't cleared up yet.

Regards,

Elfving

RE: I'm trying to control the brightness of the LEDs of my dev kit with the buttons

Elfving — Fri, 13 May 2022 13:24:49 GMT

Hello Bastien,

I will get back to you on this next week.

Regards,

Elfving