FlintESPJVM

FlintESPJVM

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.

Key Features

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

How to use

1. Supported Boards

FlintESPJVM is compatible with a variety of ESP32 boards, including: | Board | Cores | Flash | SRAM | PSRAM | | ----------------- | ------------------------- | ----- | ----- | ----- | | Generic ESP32 | 240MHz Xtensa Dual-core | 4MB | 520KB | ❌ | | ESP32-C3FH4 | 160MHz RISC-V Single-core | 4MB | 400KB | ❌ | | ESP32-C6FH4 | 160MHz RISC-V Single-core | 4MB | 512KB | ❌ | | ESP32-C6FH8 | 160MHz RISC-V Single-core | 8MB | 512KB | ❌ | | ESP32-S2FN4R2 | 240MHz Xtensa Single-core | 4MB | 320KB | 2MB | | ESP32-S3FH4R2 | 240MHz Xtensa Dual-core | 4MB | 512KB | 2MB | | ESP32-S3N4RX | 240MHz Xtensa Dual-core | 4MB | 512KB | ✅ | | ESP32-S3N8RX | 240MHz Xtensa Dual-core | 8MB | 512KB | ✅ | | ESP32-S3N16RX | 240MHz Xtensa Dual-core | 16MB | 512KB | ✅ |

2. Flashing the Firmware

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.

3. Building Java Projects for FlintESPJVM

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.

4. Dependencies and Cloning

• 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

Benchmark

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 v1.1.7 | 9254 ms | 9254 ms | 295 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.