FlintESPJVM brings the power of Java to ESP32 devices by implementing FlintJVM on the ESP-IDF framework. This enables running and debugging JVM-based languages such as Java, Kotlin, Scala, Groovy, Clojure, JRuby, and Jython on ESP32 hardware.

• Supports most Java bytecode instructions.
• Supports debugging with FlintJVM Debug VS Code extension via serial port.

FlintESPJVM is compatible with a variety of ESP32 boards, including:

To get FlintESPJVM up and running on your board:

• Quick Flash: Use the ESP Web Tool for an easy, browser-based flashing experience.
• Manual Build: Prefer building it yourself? Utilize the ESP-IDF framework to compile and flash the project manually.

To develop Java applications for FlintESPJVM:

• Project Setup: Use the FlintJDK module to access core Java libraries compatible with FlintJVM.
• Debugging: Install the FlintJVM Debug extension in VS Code.

Refer to the FlintExample project, which provides a simple and clear template to help you get started with building Java apps for FlintJVM.

• This project requires ESP-IDF v5.5.0 or later to build.
• Run the following command to clone this repository and include all dependent submodules:

> git clone --recurse-submodules https://github.com/FlintVN/FlintESPJVM.git

Below are the performance benchmarks of several different programming languages on the ESP32, focusing on:

• Execution time of 10 million iterations using for and while loops.

• Maximum toggling frequency of GPIO when driven by the CPU.

  Language	Platform	for loop (10M)	while loop (10M)	GPIO toggle frequency
  C	IDF v5.5.0	375 ms	375 ms	2.2 MHz
  Java	FlintJVM v2.4.1	8920 ms	8920 ms	294 KHz
  MicroPython	MicroPython v1.26.0	43677 ms	79582 ms	107 KHz
  C#	NanoFramework v1.12.4	77656 ms	77660 ms	2.4 KHz

The source code of this test can be viewed at ESP32-Perfomance.