PyMCU for PyCharm

Official PyCharm / IntelliJ support for PyMCU — a compiler that turns a statically-typed subset of Python into bare-metal firmware for AVR, RP2040 / RP2350, PIC and RISC-V microcontrollers. No runtime, no interpreter, no VM.

The plugin is a thin layer over the pymcu CLI: everything it knows about your boards, your sources and the language subset comes from the driver, so the two never drift.

Features

• Build, flash and clean as run configurations, with pymcuc diagnostics turned into clickable file:line:col links in the console. --verbose, --explain and --debug are checkboxes.
• Porting assistant — pymcu lint findings appear as editor annotations as you type or save, each with a concrete rewrite, plus a navigable list in the PyMCU tool window. Paste MicroPython code and follow the squiggles until it compiles.
• Resolution and completion for pymcu.*, the MicroPython / CircuitPython compat layers (machine, board, digitalio, …) and the generated board module for your target — always to the source, never to a stub. Ctrl-click pin.value(1) and you land on the code that toggles the register, not on def value(...) -> int: ....
• Navigation follows the compile-time dispatch. The HAL picks its implementation from __CHIP__, so one name exists once per architecture and again once per chip. The plugin evaluates those conditions against your target, so Ctrl-click on an Arduino Uno project lands in hal/avr/gpio/atmega328p.py and not in a Leonardo's or an RP2040's. The branches your target does not build are greyed out in the editor.
• Project configuration dialog — board, clock, compat stdlib, programmer, serial port and AVR fuses, written back to [tool.pymcu] without disturbing your comments or formatting. The board list comes from pymcu boards --json, so it matches whatever backends you have installed.
• Library manager — browse, install and remove PyMCU libraries in the tool window. The index records whether each library actually built for each chip, so an incompatible one says why instead of failing at build time.
• pyproject.toml inspection — the deprecated chip key, a board/target conflict, a missing target and an unknown board are flagged in the editor, each with the fix. Edits preserve your comments and formatting.
• Get Started checklist — the path from empty project to flashed board, with every step computed from what is actually on disk. It doubles as the place to look when an import will not resolve.
• Status bar target indicator that opens that dialog, a serial-port picker on flash, and a New Project wizard that scaffolds through pymcu new — the same project the CLI would create, toolchain and programmer included, so it builds and flashes without further edits.

Requirements

• PyCharm (Community or Professional) 2024.3 or newer, or IntelliJ IDEA with the Python plugin.
• The PyMCU CLI: pipx install pymcu-compiler, or add pymcu-compiler to your project with uv. The plugin looks for .venv/bin/pymcu first, then PATH.

Actions

All under Tools | PyMCU, and on the PyMCU tool window's toolbar.

Action	Runs
Build	pymcu build (⌃⇧B / Ctrl+Shift+B)
Flash	pymcu flash, asking which port when none is pinned
Clean	pymcu clean
Build and Explain	pymcu build --explain — reports the setup the compiler injected implicitly
Lint Project (Porting Assistant)	pymcu lint over the configured sources
Sync Project	dependency install, then pymcu sync and pymcu stubs
Export Type Stubs…	pymcu stubs, for type checkers outside the IDE
Serial Monitor	a console on the board's UART, at the project's stdout_baud
Configure Project…	the board / flash configuration dialog

The tool window has three tabs: Get Started (setup checklist), Libraries (install and remove) and Porting (assistant findings).

Settings

Settings | Tools | PyMCU

Setting	Default	Meaning
PyMCU executable	pymcu	Empty or pymcu resolves .venv/bin/pymcu, then PATH
Package manager	uv	Used by Sync: uv sync, pip install -e ., poetry install, pipenv install
Run porting assistant	onSave	onSave, onType or off
Compat flavor	auto	auto derives it from the project's stdlib setting
Report only hard blockers	off	Passes --errors-only to pymcu lint
Offer to sync on open	on	Offers a sync when generated files are missing; never syncs unasked

Getting started

1. New Project | PyMCU, or open a folder whose pyproject.toml has a [tool.pymcu] section.
2. Pick your board in Tools | PyMCU | Configure Project… — it shows in the status bar.
3. Write Python, or paste MicroPython / CircuitPython code and follow the porting assistant.
4. Build, then Flash.

Installing a build

Until the plugin is on the Marketplace, install it from a .zip:

PyCharm → Settings → Plugins → ⚙ → Install Plugin from Disk… → pick the zip → restart.

• Latest main: the dev prerelease, rebuilt on every push. Direct link: https://github.com/PyMCU/jetbrains-pymcu/releases/download/dev/jetbrains-pymcu-dev.zip
• Built yourself: ./gradlew buildPlugin → build/distributions/jetbrains-pymcu-<version>.zip

The target machine needs PyCharm 2024.3+ and the PyMCU CLI. It does not need a JDK or Gradle.

Experimental features

Work that is merged but not ready is off behind a registry key. To try one: Help → Find Action → Registry…, then search for the key.

Key	Default	What it gates
pymcu.debugger.enabled	off	Emulator debugging. Not implemented yet — turning it on currently changes nothing.

Building from source

./gradlew buildPlugin      # → build/distributions/jetbrains-pymcu-<version>.zip
./gradlew test             # unit tests
./gradlew runIde           # a sandboxed PyCharm with the plugin loaded
./gradlew verifyPlugin     # JetBrains plugin verifier, as run in CI

Requires JDK 21. Gradle finds it on PATH/JAVA_HOME automatically on most setups; if you need to point at a specific JDK, set org.gradle.java.home in your own ~/.gradle/gradle.properties rather than this project's (a per-machine path here would break the build for everyone else).

Requirements on the CLI

Some features need a pymcu new enough to answer in JSON. Older CLIs degrade rather than break — the affected panel says so and the rest keeps working.

Feature	Needs
Board catalog	pymcu boards --json
Porting assistant	pymcu lint --json
Library manager	pymcu libraries --json, pymcu search --json

Reading the stdlib

PyMCU's claim is that the abstraction is free — pin.value(1) compiles to the same SBI a C programmer would write by hand. That claim is only checkable if you can read the code, so the plugin never resolves to a generated stub:

• Go to declaration on anything from machine, digitalio or board opens the real implementation, comments and @inline decorators included.
• The sync does not generate .pyi files. An earlier version did, and it made the stdlib a black box for a little tidiness in the type hints — a bad trade for this project.
• Types are not lost by it: annotations reference pymcu.types, an installed package the interpreter resolves on its own, so uint8 reads as uint8 rather than as a stubbed int.
• Build and Explain (pymcu build --explain) is the other half: it reports the setup the compiler injected implicitly — clock init, stdout UART, ISR vectors.

Export Type Stubs… still exists for mypy or pyright running outside the IDE. The editor ignores what it writes.

Relationship to the VS Code extension

The two extensions target the same workflow and the same CLI surface. Where they differ, it is because the host does: PyCharm gets run configurations and a Swing dialog where VS Code gets tasks and a webview; VS Code writes python.analysis.extraPaths for Pylance where PyCharm gets an AdditionalLibraryRootsProvider. Behaviour, settings names and defaults are kept in step.

License

MIT — see LICENSE.