ESP32-IDF —HelloWorld Get Started

How To Get Started — ESP_IDF_Series Episode #03

Published in

Jungletronics

5 min readJun 10, 2020

This post will review the code example published by Espressif located at directory <IDF_PATH>\examples\get-started\blink of ESP-IDF installation.

It follows the CMake build system software environment for the hardware-based on the ESP32 chip produced by Expressif.

For official tutorial, please head over to:
(the stable version as of June 2020): https://docs.espressif.com/projects/esp-idf/en/stable/)

For Installation of ESP-IDF (Expressif IoT Development Framework) on Windows 10 using the CMake-based build system please take a look at this other post.

These are the steps for an ESP-IDF project:

ESP-IDFMenu Configuration
Building
Flashing firmware onto an ESP32 board

Let me show you what I have in my atelier:)

Fig 1. WiFi LoRa 32 (v2) is a classic IoT dev-board designed & produced by Heltec Automation(TM), it’s a highly integrated product based on ESP32 + SX127x, it has Wi-Fi, BLE, LoRa functions, also Li-Po battery management system, 0.96″ OLED are also included. It’s my choice :)

Fig 2. 24M Byte (32M bit )Pro ESP32 OLED V2.0 TTGO & For Arduino ESP32 OLED WiFi Modules+Bluetooth Double ESP-32 ESP8266 OLED from AliExpress.com

Material Needed

ESP32 kit board
High quality Type B-Micro USB Cable

The ESP-IDF is an amalgamation of a number of components:

1.ESP32 base library;
2.WiFi Drivers;
3.TCP/IP stack;
4.FreeRTOS stack;
5.Webserver;
6.Driver for sensor(s);
7.Main code tying it all together

Follows some concepts and jargons about ESP-IDF:

. ESP-IDF makes these components explicit & configurable;
. To config project use text-based new system (customizable);
. After config, the build system will compile the project;
. The app is inside a directory with all the support files;
. You can modify project config (sdkconfig file) by typing idf.py menuconfig at prompt;
. 1 project builds 2 apps: a) proj app = exe & b) boot app = launcher;
. components = modular pieces linked into app;
. target = hadware = ESP32;
. IDF_PATH = link ESP-IDF project;
. Toolchain = for compilation - should be on the PATH;

Annotation about The CMake-based build system:

There are 2 main build Tools: CMake + Ninja to build a full Application for ESP32 (this post) or GNU Make build system (other post);For CMake build system:
. The CMake-based build system is a front-end command line tool;
. What is idf.py ? idf.py is a top-level config/build command line tool for ESP-IDF;
. It easily managing your project builds;
. esptool.py = Flasher;
. idf.py is a wrapper around CMake for programmer convinience;
. idf.py Commands: 
idf.py menuconfig = to config the app;
idf.py build = multiple steps build process; it creaes sub-directories; run Ninja or GNU Make; Building is incremental (no-change; nothing done)
idf.py clean = delating build output files except config files; 
idf.py fullclean = delete build directory recursively;
idf.py flash -p PORT -b BAUD RATE = it flashes prog onto chip;
idf.py monitor -p PORT -b BAUD RATE = Serial output;
. You can combine commands, like this: idf.py -p COM4 flash monitor;
. The order is not important (it automatically will be executed in the correct order);
. Python interpreter - ESP-IDF works with Python 2.7 or 3.8;

Here is the layout that the ESP-IDF Tools Installer makes in my machine:

Fig 3. ESP-IDF official layout 4 Win10:)

Here is an Espressif recommended ESP-IDF project layout directory (for my custom project I put it inside the Directory Examples above and worked fine):

Fig 4. A project layout simplified for your reference

Setup Path to ESP-IDF

IDF_PATH = 
C:\Users\%userprofile%\Desktop\esp-idfIDF_PYTHON_ENV_PATH = C:\Users\%userprofile%\.espressif\python_env\idf3.3_py3.8_envIDF_TOOLS_PATH = 
C:\Users\%userprofile%\.espressif

Fine, now let’s code o/

The first example that I will review is the blink project.

You can find it at this location: C:\Users\%userprofile%\Desktop\esp-idf\examples\get-started\blink.

Here is the blink.c code at \main sub-directory: