Initial

.gitignore

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+.idea/
+build
+cmake-build-*

CMakeLists.txt

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+# The following lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(hello-world)

Makefile

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+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+
+PROJECT_NAME := hello-world
+
+include $(IDF_PATH)/make/project.mk

README.md

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+# Hello World Example
+
+Starts a FreeRTOS task to print "Hello World".
+
+(See the README.md file in the upper level 'examples' directory for more information about examples.)
+
+## How to use example
+
+Follow detailed instructions provided specifically for this example. 
+
+Select the instructions depending on Espressif chip installed on your development board:
+
+- [ESP32 Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/stable/get-started/index.html)
+- [ESP32-S2 Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/esp32s2/get-started/index.html)
+
+
+## Example folder contents
+
+The project **hello_world** contains one source file in C language [hello_world_main.c](main/hello_world_main.c). The file is located in folder [main](main).
+
+ESP-IDF projects are built using CMake. The project build configuration is contained in `CMakeLists.txt` files that provide set of directives and instructions describing the project's source files and targets (executable, library, or both). 
+
+Below is short explanation of remaining files in the project folder.
+
+```
+├── CMakeLists.txt
+├── example_test.py            Python script used for automated example testing
+├── main
+│   ├── CMakeLists.txt
+│   ├── component.mk           Component make file
+│   └── hello_world_main.c
+├── Makefile                   Makefile used by legacy GNU Make
+└── README.md                  This is the file you are currently reading
+```
+
+For more information on structure and contents of ESP-IDF projects, please refer to Section [Build System](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/build-system.html) of the ESP-IDF Programming Guide.
+
+## Troubleshooting
+
+* Program upload failure
+
+    * Hardware connection is not correct: run `idf.py -p PORT monitor`, and reboot your board to see if there are any output logs.
+    * The baud rate for downloading is too high: lower your baud rate in the `menuconfig` menu, and try again.
+
+## Technical support and feedback
+
+Please use the following feedback channels:
+
+* For technical queries, go to the [esp32.com](https://esp32.com/) forum
+* For a feature request or bug report, create a [GitHub issue](https://github.com/espressif/esp-idf/issues)
+
+We will get back to you as soon as possible.

main/CMakeLists.txt

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+idf_component_register(SRCS "hello_world_main.c"
+                    INCLUDE_DIRS "")

main/component.mk

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+#
+# "main" pseudo-component makefile.
+#
+# (Uses default behaviour of compiling all source files in directory, adding 'include' to include path.)

main/hello_world_main.c

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+/* Hello World Example
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include <stdio.h>
+#include "sdkconfig.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "esp_system.h"
+#include "esp_spi_flash.h"
+#include "driver/ledc.h"
+
+void app_main(void)
+{
+  printf("Hello world!\n");
+
+  /*
+   * Prepare and set configuration of timers
+   * that will be used by LED Controller
+   */
+  ledc_timer_config_t ledc_timer = {
+      .duty_resolution = LEDC_TIMER_8_BIT, // resolution of PWM duty
+      .freq_hz = 38500,                      // frequency of PWM signal
+      .speed_mode = LEDC_HIGH_SPEED_MODE,           // timer mode
+      .timer_num = LEDC_TIMER_0,            // timer index
+      .clk_cfg = LEDC_AUTO_CLK,              // Auto select the source clock
+  };
+  // Set configuration of timer0 for high speed channels
+  ledc_timer_config(&ledc_timer);
+
+  ledc_channel_config_t chan = {
+      .channel    = LEDC_CHANNEL_0,
+      .duty       = 127,
+      .gpio_num   = 17,
+      .speed_mode = LEDC_HIGH_SPEED_MODE,
+      .hpoint     = 0,
+      .timer_sel  = LEDC_TIMER_0
+  };
+  ledc_channel_config(&chan);
+
+#define PWM_ON() do { \
+  ledc_set_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0, 127); \
+  ledc_update_duty(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0); \
+} while(0)
+
+#define PWM_OFF() do { \
+  ledc_stop(LEDC_HIGH_SPEED_MODE, LEDC_CHANNEL_0, 0); \
+} while(0)
+
+  while (1) {
+    //const uint8_t bytes[4] = {0b10000000, 0b01111111, 0b00010000, 0b11101111}; // and one 1 at the end
+    const uint8_t bytes[4] = {0b10000000 , 0b01111111 , 0b00000000 , 0b11111111}; // and one 1 at the end
+
+    // Preamble
+    PWM_ON();
+    ets_delay_us(9000);
+    PWM_OFF();
+    ets_delay_us(4500);
+
+    for (int i = 0; i < 4; i++) {
+      uint8_t byte = bytes[i];
+      for (int j = 0; j < 8; j++) {
+        bool bit = 0 != (byte & 0x80);
+        byte <<= 1;
+        if (bit==0) {
+          PWM_ON();
+          ets_delay_us(588);
+          PWM_OFF();
+          ets_delay_us(540);
+        } else {
+          PWM_ON();
+          ets_delay_us(590);
+          PWM_OFF();
+          ets_delay_us(1672);
+        }
+      }
+    }
+
+    PWM_ON();
+    ets_delay_us(600);
+    PWM_OFF();
+    ets_delay_us(1700);
+
+    vTaskDelay(pdMS_TO_TICKS(1000));
+  }
+}