# Building CircuitPython

Welcome to CircuitPython!

This document is a quick-start guide only.

Detailed guides on how to build CircuitPython can be found in the Adafruit Learn system at
https://learn.adafruit.com/building-circuitpython/

## Setup

Please ensure you setup your build environment appropriately, as per the guide.  You will need:

* Linux: https://learn.adafruit.com/building-circuitpython/linux
* MacOS: https://learn.adafruit.com/building-circuitpython/macos
* Windows Subsystem for Linux (WSL): https://learn.adafruit.com/building-circuitpython/windows-subsystem-for-linux

### Submodules

This project has a bunch of git submodules.  You will need to update them regularly.

    git submodule sync
    git submodule update --init

### mpy-cross

As part of the build process, mpy-cross is needed to compile .py files into .mpy files.
To compile (or recompile) mpy-cross:

    make -C mpy-cross

# Building

There a number of ports of CircuitPython!  To build for your board, change to the appropriate ports directory and build.

Examples:

    cd ports/atmel-samd
    make BOARD=circuitplayground_express

    cd ports/nrf
    make BOARD=circuitplayground_bluefruit

If you aren't sure what boards exist, have a peek in the boards subdirectory of your port.
If you have a fast computer with many cores, consider adding `-j` to your build flags, such as `-j17` on
a 6-core 12-thread machine.

# Testing

If you are working on changes to the core language, you might find it useful to run the test suite.
The test suite in the top level `tests` directory.  It needs the unix port to run.

    cd ports/unix
    make axtls
    make micropython

Then you can run the test suite:

    cd ../../tests
    ./run-tests

A successful run will say something like

    676 tests performed (19129 individual testcases)
    676 tests passed
    30 tests skipped: buffered_writer builtin_help builtin_range_binop class_delattr_setattr cmd_parsetree extra_coverage framebuf1 framebuf16 framebuf2 framebuf4 framebuf8 framebuf_subclass mpy_invalid namedtuple_asdict non_compliant resource_stream schedule sys_getsizeof urandom_extra ure_groups ure_span ure_sub ure_sub_unmatched vfs_basic vfs_fat_fileio1 vfs_fat_fileio2 vfs_fat_more vfs_fat_oldproto vfs_fat_ramdisk vfs_userfs

# Debugging

The easiest way to debug CircuitPython on hardware is with a JLink device, JLinkGDBServer, and an appropriate GDB.
Instructions can be found at https://learn.adafruit.com/debugging-the-samd21-with-gdb

If using JLink, you'll need both the `JLinkGDBServer` and `arm-none-eabi-gdb` running.

Example:

    JLinkGDBServer -if SWD -device ATSAMD51J19
    arm-none-eabi-gdb build-metro_m4_express/firmware.elf -iex "target extended-remote :2331"

If your port/build includes `arm-none-eabi-gdb-py`, consider using it instead, as it can be used for better register
debugging with https://github.com/bnahill/PyCortexMDebug