pymcu-avr-toolchain

Pre-built AVR-GCC toolchain for the PyMCU AVR (ATmega/ATtiny) backend.

The AVR backend compiles PyMCU's architecture-agnostic IR to AVR assembly and then invokes three core tools to produce a flashable Intel HEX file:

avr-gcc   avr-as   avr-objcopy

(Full toolchain also includes avr-g++, avr-ld, avr-ar, avr-objdump, avr-size, avr-gdb, and avr-libc.)

This package is the AVR counterpart of pymcu-rp2040-toolchain: a platform-specific wheel whose only job is to ship those tools so that pip install pymcu-compiler[avr] is fully self-contained — no separate avr-gcc installation required on supported platforms.

The build script (avr-gcc-build.sh) is based on the work of Zak Kemble.

License: GPL-3.0-or-later packaging + binaries

The bundled AVR-GCC toolchain is derived from GCC and Binutils, which are licensed under GPL-3.0-or-later and LGPL-3.0-or-later respectively. avr-libc is BSD-2-Clause. Because the wheel bundles GPL code, the package as a whole is distributed under GPL-3.0-or-later.

  • The GPL applies to the toolchain binaries themselves, not to the firmware your projects compile with them. Firmware produced by avr-gcc is your own work and carries no GPL obligation.
  • Contrast with RP2040: pymcu-rp2040-toolchain bundles LLVM, which is Apache-2.0 WITH LLVM-exception (permissive, no copyleft). The isolation mechanism is the same — a separate optional package — but the license differs because the upstream compilers differ.

See LICENSES/ and NOTICE for the full texts.

Bundled versions

Tool Version
avr-gcc 15.2.0
avr-binutils 2.45
avr-gdb 16.3
avr-libc latest

Installation

pip install pymcu-avr-toolchain

avr-gcc + avr-libc together exceed PyPI's 100 MB per-file ceiling (~150 MB per platform). The distribution is therefore split:

Channel What it contains
PyPI (pip install pymcu-avr-toolchain) Lightweight stub (~14 KB)
GitHub Releases Binary wheels with the full toolchain (~150 MB each)

The binary wheel is downloaded automatically. The first call to get_bin_dir() (or any PyMCU build that needs the toolchain) downloads the correct wheel for your platform from GitHub Releases and extracts it to the shared cache at ~/.pymcu/tools/. Subsequent calls are instant.

import pymcu_avr_toolchain
bin_dir = pymcu_avr_toolchain.get_bin_dir()   # downloads on first call

For CI or air-gapped environments, set PYMCU_AVR_WHEEL_URL to override the download URL, or install the binary wheel directly:

# Linux x86-64
pip install https://github.com/PyMCU/avr-gcc-build/releases/download/v15.2.0.post5/pymcu_avr_toolchain-15.2.0.post5-py3-none-manylinux_2_17_x86_64.whl

# Linux arm64 (best-effort build)
pip install https://github.com/PyMCU/avr-gcc-build/releases/download/v15.2.0.post5/pymcu_avr_toolchain-15.2.0.post5-py3-none-manylinux_2_17_aarch64.whl

# macOS Apple Silicon
pip install https://github.com/PyMCU/avr-gcc-build/releases/download/v15.2.0.post5/pymcu_avr_toolchain-15.2.0.post5-py3-none-macosx_14_0_arm64.whl

# Windows x86-64
pip install https://github.com/PyMCU/avr-gcc-build/releases/download/v15.2.0.post5/pymcu_avr_toolchain-15.2.0.post5-py3-none-win_amd64.whl

System toolchain (alternative)

If you already have avr-gcc installed, the AvrToolchain driver finds the tools automatically via PATH — no package needed:

# macOS
brew tap osx-cross/avr && brew install avr-gcc

# Debian/Ubuntu
apt install gcc-avr binutils-avr avr-libc

Linux arm64: Built on GitHub's ubuntu-24.04-arm runner. The build script was designed for Linux x64; the arm64 build is best-effort (continue-on-error) and may be absent from a release if the runner fails.

macOS Intel (x86-64): The osx-cross/avr tap does not provide x86-64 bottles for avr-gcc, so no Intel wheel is published.

How the driver resolves tools

AvrToolchain (in pymcu-avr) checks these sources in order:

Priority Source
1 pymcu_avr_toolchain.get_bin_dir() — wheel bundle or auto-downloaded cache
2 Shared cache ~/.pymcu/tools/<platform>/pymcu-avr-toolchain/<version>/bin/
3 Common keg dirs (/opt/homebrew/opt/avr-gcc/bin, /usr/bin, …)
4 PATH

A missing wheel never blocks a developer who already has avr-gcc installed.

Inspecting installed tools

pymcu-avr-toolchain-info     # entry-point
python -m pymcu_avr_toolchain

For maintainers: publishing a new wheel

Release process

  1. Update VER_GCC, VER_BINUTILS, VER_GDB in avr-gcc-build.sh and version in python/pyproject.toml.
  2. Tag and push: 
    git tag v15.2.0
git push origin v15.2.0
  3. The build-wheels.yml workflow fires automatically:
    • Builds one binary wheel per platform (Linux x64 from source ~2 h, Linux arm64 best-effort, macOS via Homebrew, Windows via MSYS2).
    • Binary wheels → GitHub Releases (too large for PyPI's 100 MB limit).
    • PyPI receives only the pure-Python sdist stub.
    • publish-pypi uses OIDC trusted publishing (no stored token required).

Required GitHub configuration

Item Where Purpose
release environment Repo → Settings → Environments Gates OIDC publishing; add tag protection rule v*

Building a wheel locally

AVRT_TOOLCHAIN_DIR=build/avr-gcc-15.2.0-x64-linux \
WHEEL_PLATFORM_TAG=manylinux_2_17_x86_64 \
uv build --wheel python/

Environment variables

Variable Effect
AVRT_TOOLCHAIN_DIR Path to a staged AVR-GCC tree for hatch_build.py
AVRT_GCC_VERSION Inject GCC version string for cross-build CI steps
WHEEL_PLATFORM_TAG Override the wheel platform tag (e.g. win_amd64)
PYMCU_AVR_WHEEL_URL Override the binary wheel download URL (air-gapped installs)
PYMCU_TOOLS_DIR Override the ~/.pymcu/tools cache root
PYMCU_TOOLCHAIN_NO_SEEDING Set to 1 to use the in-package bin/ directly without seeding the cache

Version history

Package version avr-gcc Notes
15.2.0.post5 15.2.0 Fix project URLs; auto-download on first use
15.2.0 15.2.0 Initial release

Project links

Data verified by PyPI on Aug 13, 2026
Data provided by the project maintainers, verified at the time the release was uploaded to PyPI.

Key dates

PyPI data
Data sourced directly from PyPI's database.
  • Released:
Newer release available (1!14.2.0)

1 maintainer

PyPI data
Data sourced directly from PyPI's database.
Avatar for pymcu from gravatar.com pymcu

Credits

Author: Iván Montiel Cardona

GitHub Statistics

Data verified by PyPI on Aug 13, 2026
The GitHub source repository was provided by the project maintainers and verified by PyPI at the time of upload. Stars, forks, and open issues/PRs are derived from that repository and have not been independently verified.

License

GPL-2.0-or-later AND LGPL-2.1-or-later AND BSD-2-Clause

Requires

Python >=3.11

Tags

avr avr-gcc cross-compiler embedded gcc pymcu toolchain

Classifiers

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