├── CMakeLists.txt
├── esp32.overlay
├── prj.conf
└── src
    └── main.c


/CMakeLists.txt:
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1 | cmake_minimum_required(VERSION 3.22)
2 | set(BOARD esp32)
3 | 
4 | find_package(Zephyr)
5 | project(hello_world_blinky)
6 | 
7 | target_sources(app PRIVATE src/main.c)
8 | 


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/esp32.overlay:
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 1 | / {
 2 | 	pwmleds {
 3 | 		compatible = "pwm-leds";
 4 | 		fading_led: fading_led {
 5 | 			    pwms = <&ledc0 0 10000 PWM_POLARITY_NORMAL>;
 6 | 		};
 7 | 	};
 8 | };
 9 | 
10 | &pinctrl {
11 |         ledc0_default: ledc0_default {
12 | 	        group1 {
13 | 		        pinmux = <LEDC_CH0_GPIO25>;
14 | 			output-enable;
15 | 		};
16 | 	};
17 | };
18 | 
19 | &ledc0 {
20 |         pinctrl-0 = <&ledc0_default>;
21 | 	pinctrl-names = "default";
22 |         status = "okay";
23 | 	#address-cells = <1>;
24 | 	#size-cells = <0>;
25 | 	channel0@0 {
26 | 	        reg = <0x0>;
27 | 		timer = <0>;
28 | 	};
29 | };


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/prj.conf:
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1 | CONFIG_PWM=y


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/src/main.c:
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 1 | #include <zephyr/kernel.h>
 2 | #include <zephyr/device.h>
 3 | #include <zephyr/drivers/pwm.h>
 4 | 
 5 | #define NUM_STEPS 100U
 6 | #define SLEEP_DELTA_MSEC 20U
 7 | 
 8 | static const struct pwm_dt_spec fading_led =
 9 |   PWM_DT_SPEC_GET(DT_NODELABEL(fading_led));
10 | 
11 | static uint32_t pulse_width_nsec = 0U;
12 | static uint32_t pulse_width_delta_nsec = 0U;
13 | static uint32_t steps_taken = 0U;
14 | static bool increasing_intensity = true;
15 | int ret;
16 | 
17 | void led_delta_timer_handler(struct k_timer *timer_info)
18 | {
19 |   if (increasing_intensity) {
20 |     if (steps_taken < NUM_STEPS) {
21 |       ret = pwm_set_pulse_dt(&fading_led, pulse_width_nsec);
22 |       steps_taken++;
23 |       pulse_width_nsec += pulse_width_delta_nsec;
24 |     } else {
25 |       increasing_intensity = false;
26 |       steps_taken--;
27 |       pulse_width_nsec -= pulse_width_delta_nsec;
28 |     }
29 |   } else {
30 |     if (steps_taken > 0) {
31 |       ret = pwm_set_pulse_dt(&fading_led, pulse_width_nsec);
32 |       steps_taken--;
33 |       pulse_width_nsec -= pulse_width_delta_nsec;
34 |     } else {
35 |       increasing_intensity = true;
36 |       steps_taken++;
37 |       pulse_width_nsec += pulse_width_delta_nsec;
38 |     }
39 |   }
40 | }
41 | 
42 | K_TIMER_DEFINE(led_delta_timer, led_delta_timer_handler, NULL);
43 | 
44 | void main(void)
45 | {
46 |   if (!device_is_ready(fading_led.dev)) {
47 |     printk("Error: PWM device %s is not ready\n",
48 | 	   fading_led.dev->name);
49 |     return;
50 |   }
51 | 
52 |   pulse_width_delta_nsec = fading_led.period / NUM_STEPS;
53 |   
54 |   k_timer_start(&led_delta_timer, K_MSEC(SLEEP_DELTA_MSEC),
55 | 		K_MSEC(SLEEP_DELTA_MSEC));
56 | }
57 | 


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