To use as a component of ESP-IDF

Installation

Download and install esp-idf v4.2 release
Create blank idf project (from one of the examples)

in the project folder, create a folder called components and clone this repository inside

mkdir -p components && \
cd components && \
git clone -single-branch --branch mod-idf-v4.2 https://github.com/summivox/arduino-esp32.git arduino && \
cd arduino && \
git submodule update --init --recursive && \
cd ../.. && \
make menuconfig

If the project is already in a git repo, use these instead:

mkdir -p components && \
git submodule add https://github.com/summivox/arduino-esp32 arduino --branch mod-idf-v4.2 --recursive

make menuconfig has some Arduino options
- important: you MUST enable these to build
  - mbedTLS: Enable pre-shared-key ciphersuites
  - bluetooth: At least enable BLE and Bluedroid
- "Autostart Arduino setup and loop on boot"
  - If you enable this options, your main.cpp should be formated like any other sketch
```
//file: main.cpp
#include "Arduino.h"

void setup(){
  Serial.begin(115200);
}

void loop(){
  Serial.println("loop");
  delay(1000);
}
```
  - Else you need to implement app_main() and call initArduino(); in it.
    
    Keep in mind that setup() and loop() will not be called in this case. If you plan to base your code on examples provided in esp-idf, please make sure move the app_main() function in main.cpp from the files in the example.
```
//file: main.cpp
#include "Arduino.h"

extern "C" void app_main()
{
    initArduino();
    pinMode(4, OUTPUT);
    digitalWrite(4, HIGH);
    //do your own thing
}
```
- "Disable mutex locks for HAL"
  - If enabled, there will be no protection on the drivers from concurently accessing them from another thread/interrupt/core
- "Autoconnect WiFi on boot"
  - If enabled, WiFi will start with the last known configuration
  - Else it will wait for WiFi.begin
make flash monitor will build, upload and open serial monitor to your board

Logging To Serial

If you are writing code that does not require Arduino to compile and you want your ESP_LOGx macros to work in Arduino IDE, you can enable the compatibility by adding the following lines after your includes:

#ifdef ARDUINO_ARCH_ESP32
#include "esp32-hal-log.h"
#endif

FreeRTOS Tick Rate (Hz)

You might notice that Arduino-esp32's delay() function will only work in multiples of 10ms. That is because, by default, esp-idf handles task events 100 times per second. To fix that behavior you need to set FreeRTOS tick rate to 1000Hz in make menuconfig -> Component config -> FreeRTOS -> Tick rate.

FreeRTOS task watchdog time out

In menuconfig, disable "Watch CPU1 Idle Task".

Compilation Errors

As commits are made to esp-idf and submodules, the codebases can develop incompatibilities which cause compilation errors. If you have problems compiling, follow the instructions in Issue #1142 to roll esp-idf back to a known good version.