https://github.com/flintvn/flintespjvm

FlintESPJVM brings the power of Java to ESP32. Allows you to run and debug Java programs directly on the ESP32 hardware
https://github.com/flintvn/flintespjvm

esp32 flint flintespjvm flintjvm java jvm

Last synced: 2 months ago
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FlintESPJVM brings the power of Java to ESP32. Allows you to run and debug Java programs directly on the ESP32 hardware

• Host: GitHub
• URL: https://github.com/flintvn/flintespjvm
• Owner: FlintVN
• License: mit
• Created: 2024-07-25T12:57:45.000Z (almost 2 years ago)
• Default Branch: master
• Last Pushed: 2026-04-05T07:03:25.000Z (2 months ago)
• Last Synced: 2026-04-05T08:25:38.488Z (2 months ago)
• Topics: esp32, flint, flintespjvm, flintjvm, java, jvm
• Language: C++
• Homepage: https://esp.flint.vn
• Size: 14.6 MB
• Stars: 59
• Watchers: 4
• Forks: 7
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE.txt

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README

          
## FlintESPJVM

FlintESPJVM brings the power of Java to ESP32 devices by implementing [FlintJVM](https://github.com/FlintVN/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.

![demo](images/demo1.avif)

## Key Features

- Supports most Java bytecode instructions.

- Supports debugging with [FlintJVM Debug](https://marketplace.visualstudio.com/items?itemName=ElectricThanhTung.flintjvm-debugger) 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](https://esp.flint.vn) 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](https://github.com/FlintVN/FlintJDK) module to access core Java libraries compatible with FlintJVM.

- Debugging: Install the FlintJVM Debug extension in VS Code.

Refer to the [FlintExample](https://github.com/FlintVN/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:

```sh

> 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](https://github.com/FlintVN/ESP32-Perfomance).