diff --git a/.gitignore b/.gitignore
index 9e45370..8eae74a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,4 +7,5 @@ freertos*
 build
 toolchain
 
-*.orig
\ No newline at end of file
+*.orig
+*.debug
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 3bdfee6..5760c60 100644
--- a/Makefile
+++ b/Makefile
@@ -39,6 +39,10 @@ endif
 format: .check-name
 	@test -f "$(shell find /usr/bin/ -name astyle)" && astyle --style=java --indent=spaces=4 -K -xC120 $(name)/*.c
 
+run-debug: format
+	@rm -f  ${name}/${name}.debug
+	@gcc -std=c99 -o2 ${name}/*.c  -lm -o ${name}/${name}.debug && ./${name}/${name}.debug
+
 compile: format
 	rm -f ${name}/build/CMakeCache.txt
 	@(test -d ${name} && mkdir -p ${name}/build && cd ${name}/build && cmake .. && make -j$(nproc) && echo "project compile successfully") || echo "error: unable to compile project: $(name)"
diff --git a/breathing_led/CMakeLists.txt b/breathing_led/CMakeLists.txt
new file mode 100644
index 0000000..025e95e
--- /dev/null
+++ b/breathing_led/CMakeLists.txt
@@ -0,0 +1,39 @@
+# Generated Cmake Pico project file
+
+cmake_minimum_required(VERSION 3.13)
+
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# Pull in Raspberry Pi Pico SDK (must be before project)
+include($ENV{PICO_SDK_PATH}/external/pico_sdk_import.cmake)
+
+project(breathing_led C CXX ASM)
+
+# Initialise the Raspberry Pi Pico SDK
+pico_sdk_init()
+
+# Add executable. Default name is the project name, version 0.1
+
+add_executable(breathing_led main.c led_bar.c)
+add_definitions(-DPICO)
+
+pico_set_program_name(breathing_led "breathing_led")
+pico_set_program_version(breathing_led "0.1")
+
+# Modify the below lines to enable/disable output over UART/USB
+pico_enable_stdio_uart(breathing_led 0)
+pico_enable_stdio_usb(breathing_led 1)
+
+# Add the standard library to the build
+target_link_libraries(breathing_led
+        pico_stdlib hardware_pwm)
+
+# Add the standard include files to the build
+target_include_directories(breathing_led PRIVATE
+        ${CMAKE_CURRENT_LIST_DIR}
+)
+
+pico_add_extra_outputs(breathing_led)
+
diff --git a/breathing_led/led_bar.c b/breathing_led/led_bar.c
new file mode 100644
index 0000000..be54b3a
--- /dev/null
+++ b/breathing_led/led_bar.c
@@ -0,0 +1,175 @@
+
+#include "led_bar.h"
+#include <string.h>
+#include <math.h>
+
+#ifdef PICO
+#include <pico/printf.h>
+#include <pico/stdlib.h>
+#include <hardware/pwm.h>
+#else
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#endif
+
+void _sleep(size_t ms) {
+#ifdef PICO
+    sleep_ms(ms);
+#else
+    usleep(ms * 1000);
+#endif
+}
+
+void _set_pwm_gpio_level(size_t gpio, size_t level) {
+#ifdef PICO
+    pwm_set_gpio_level(gpio, level);
+#endif
+}
+
+size_t _compute_wave_level(float level) {
+    float var = (sinf(level) + 1.0) / 2.0;
+    return MAX_DUTY_STEPS * var;
+}
+
+
+void init_leds(leds *l) {
+    for (size_t i = 0; i < NB_LED_BAR_GPIO; i++) {
+        l->data[i].gpio = LED_BAR_GPIO[i];
+        l->data[i].pos = i;
+        l->data[i].level = 0;
+
+        led *next, *previous;
+        if (i != NB_LED_BAR_GPIO - 1) {
+            next = &l->data[i + 1];
+        }
+        if (i > 0) {
+            previous = &l->data[i - 1];
+        }
+
+        l->data[i].next_led = next;
+        l->data[i].previous_led = previous;
+
+        next = NULL;
+        previous = NULL;
+    }
+    l->cur = &l->data[0];
+    l->direction = FORWARD;
+}
+
+void switch_direction(leds *l) {
+    for (size_t i = 0; i < NB_LED_BAR_GPIO; i++) {
+        l->data[i].level = 0;
+
+        led *tmp = l->data[i].next_led;
+
+        l->data[i].next_led = l->data[i].previous_led;
+        l->data[i].previous_led = tmp;
+
+        tmp = NULL;
+    }
+
+    l->direction = !l->direction;
+    l->cur = !l->direction ? &l->data[0] : &l->data[NB_LED_BAR_GPIO - 1];
+    return;
+}
+
+void run_meteor(leds *l, size_t delay) {
+    led *cur = l->cur;
+    size_t max_level = MAX_DUTY_STEPS;
+
+    while (cur != NULL) {
+        set_led_level(cur, max_level);
+        size_t level = max_level - DUTY_STEP;
+
+        led *previous = cur->previous_led;
+        while (previous != NULL && previous->level) {
+            set_led_level(previous, level);
+            previous = previous->previous_led;
+            level -= DUTY_STEP;
+        }
+
+        _sleep(delay);
+        print_led_bar_state(l);
+
+        if (cur->next_led == NULL) {
+            if (!cur->level) {
+                break;
+            }
+
+            max_level -= DUTY_STEP;
+            continue;
+        }
+
+        cur = cur->next_led;
+    }
+}
+
+void print_led_bar_state(leds *l) {
+    printf("* led bar state >> ");
+    for (int i = 0; i < NB_LED_BAR_GPIO; i++) {
+        char led_state[12];
+        sprintf(led_state, "%ld (%.2ld)", l->data[i].gpio, l->data[i].level);
+        if (i != NB_LED_BAR_GPIO - 1) {
+            strcat(led_state, " | ");
+        }
+        printf("%s", led_state);
+    }
+    printf("\n");
+}
+
+
+void set_led_level(led *l, size_t level) {
+    l->level = level;
+    _set_pwm_gpio_level(l->gpio, level);
+}
+
+void breath_led(leds* l, size_t pos, size_t max_level, size_t step) {
+#ifdef PICO
+    pwm_set_wrap(l->data[pos].gpio, MAX_DUTY_STEPS);
+#endif
+    led* cur = &l->data[pos];
+
+    size_t level = 0;
+    short direction = 0;
+    for(;;) {
+        print_led_bar_state(l);
+        set_led_level(cur, level);
+        _sleep(50);
+
+        if (!direction) {
+            level += step;
+            if (level > MAX_DUTY_STEPS) {
+                level = MAX_DUTY_STEPS;
+                direction = !direction;
+            }
+            continue;
+        }
+
+        level -= step;
+        if (level <= 0) {
+            level = 0;
+            direction = !direction;
+        }
+    }
+}
+
+void run_wave(leds *l, size_t delay_ms) {
+    const float twopi = 6.14;
+    const float step = twopi / NB_LED_BAR_GPIO;
+
+    float variation = 0.0;
+    for (;;) {
+        for (size_t led_idx = 0; led_idx < NB_LED_BAR_GPIO; led_idx++) {
+            size_t level = _compute_wave_level(variation);
+            set_led_level(&l->data[led_idx], level);
+            variation += step;
+
+            if (variation> twopi)
+                variation = 0.0;
+        }
+
+        _sleep(delay_ms);
+        print_led_bar_state(l);
+    }
+}
\ No newline at end of file
diff --git a/breathing_led/led_bar.h b/breathing_led/led_bar.h
new file mode 100644
index 0000000..c1b3715
--- /dev/null
+++ b/breathing_led/led_bar.h
@@ -0,0 +1,54 @@
+
+#ifndef LED_BAR_H
+#define LED_BAR_H 1
+
+#include <stddef.h>
+
+#define NB_LED_BAR_GPIO 10
+#define MAX_DUTY_STEPS NB_LED_BAR_GPIO
+#define DUTY_STEP 1
+
+// FORWARD: left to right, BACKWARD: right to left.
+enum DIRECTION {FORWARD, BACKWARD};
+
+static const int LED_BAR_GPIO[NB_LED_BAR_GPIO] = {28, 27, 26, 22, 21,
+                                                  20, 19, 18, 17, 16};
+
+typedef struct led led;
+struct led {
+  size_t gpio;
+  size_t pos;
+  size_t level;
+
+  led *next_led;
+  led *previous_led;
+};
+
+typedef struct leds leds;
+struct leds {
+  led data[NB_LED_BAR_GPIO];
+  led *cur;
+  short direction;
+};
+
+
+// Wrapper around sleep methods (Pico SDK & GCC stdlib).
+void _sleep(size_t seconds);
+// Wrapper around `set_pwm_gpio_level`func Pico SDK.
+void _set_pwm_gpio_level(size_t gpio, size_t level);
+void set_led_level(led *l, size_t level);
+
+void print_led_bar_state(leds *l);
+
+// Initialize led bar. The default direction at initialization is `FORWARD`.
+void init_leds(leds *l);
+// Switch the current direction of the meteor flow by switching the next & previous led nodes.
+void switch_direction(leds *l);
+// Display a meteor flow like on the LED bar. Play with `delay` argument to increase/reduce flow speed.
+void run_meteor(leds *l, size_t delay_ms);
+// "Breathing" like for one led in the LED bar.
+void breath_led(leds *l, size_t pos, size_t max_level, size_t step);
+// Turns on/off the LED bar in a wave flow fashion.
+void run_wave(leds *l, size_t delay_ms);
+
+#endif
\ No newline at end of file
diff --git a/breathing_led/main.c b/breathing_led/main.c
new file mode 100644
index 0000000..f6e4dcd
--- /dev/null
+++ b/breathing_led/main.c
@@ -0,0 +1,63 @@
+#include "led_bar.h"
+
+#ifdef PICO
+#include <hardware/pwm.h>
+#include <pico/stdlib.h>
+
+#define GPIO_02 2
+#endif
+
+void init_gpio(void) {
+#ifdef PICO
+#ifdef PICO_DEFAULT_LED_PIN
+    gpio_init(PICO_DEFAULT_LED_PIN);
+    gpio_set_dir(PICO_DEFAULT_LED_PIN, GPIO_OUT);
+#endif
+    gpio_init(GPIO_02);
+    gpio_set_dir(GPIO_02, GPIO_OUT);
+
+    gpio_set_function(GPIO_02, GPIO_FUNC_PWM);
+    uint slice_num = pwm_gpio_to_slice_num(GPIO_02);
+    pwm_set_enabled(slice_num, true);
+
+    for (int i = 0; i < NB_LED_BAR_GPIO; i++) {
+        gpio_init(LED_BAR_GPIO[i]);
+        gpio_set_dir(LED_BAR_GPIO[i], GPIO_OUT);
+
+        gpio_set_function(LED_BAR_GPIO[i], GPIO_FUNC_PWM);
+
+        uint slice_num = pwm_gpio_to_slice_num(LED_BAR_GPIO[i]);
+        pwm_set_enabled(slice_num, true);
+        pwm_set_wrap(slice_num, MAX_DUTY_STEPS);
+    }
+#endif
+}
+
+/**
+ * A program to play with the LED bar (10 leds).
+ * You have three main functions:
+ * - run_wave: simulate waves like propagating along the LED bar.
+ * - breath_led: one LED breathing (for manu use FreeRTOS tasks).
+ * - run_meteor: back and forth meteor flow like.
+ * 
+ * NOTE: for easy dev/debug you can use the following command:
+ * `make run-debug name=beathing_led`
+ * 
+ * It will run the program directly on your machine, displaying
+ * a LED bar simulator on the terminal stdout.
+ */
+int main() {
+#ifdef PICO
+    stdio_init_all();
+    init_gpio();
+#endif
+    leds l;
+    init_leds(&l);
+
+    run_wave(&l, 100);
+    breath_led(&l, 5, 100, 1);
+    for(;;) {
+        run_meteor(&l, 100);
+        switch_direction(&l);
+    }
+}
\ No newline at end of file