98 lines
2.9 KiB
Markdown
98 lines
2.9 KiB
Markdown
---
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title: "Arduino, Big Builder, and Make"
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date: 2024-01-05
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tags:
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- computers
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- ci/cd
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---
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Last night,
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I got Big Builder building Arduino sketches.
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Big Builder is my Continuous Integration / Continuious Development (ci/cd)
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solution for forgejo/gitea.
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It's nothing revolutionary,
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it's just a container with a bunch of pre-installed software,
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and the gitea `act_runner` with a configuration to *not* try and use docker.
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This means my builds are pretty quick,
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and my network use is very low,
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since I already have the tools I need to build stuff,
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and don't have to download mulitple OS images every time I do a build.
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## Automating embedded systems builds
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Arduino, it turns out,
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has been including command-line build tools for a long time now.
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Since I'm using Debian's Arduino package,
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I get the older, poorly-documented `arduino-builder`.
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But the newer `arduino-cli` has better documentation,
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that helped me understand how to use the older command.
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Using `arduino-builder` lets me keep the source code structured
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in a way that makes sense to amateur developers:
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they can just load it up in the IDE and not worry about my automation.
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But it also lets me automate builds on my forgejo server,
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and use the command-line to build everything,
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the way I've been doing since the 80s.
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Here's what I wound up with,
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to build a Leonardo image:
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```sh
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mkdir -p build/cache
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arduino-builder \
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-build-path $(pwd)/build/ \
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-build-cache $(pwd)/build/cache/ \
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-fqbn arduino:avr:leonardo \
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-hardware /usr/share/arduino/hardware/ \
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-tools /usr/share/arduino/tools/ \
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-compile MockBand.ino
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```
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This results in `build/MockBand.ino.hex`,
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which can then be given to `avrdude` to flash my board.
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Easy!
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----
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For the mockband project,
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I also needed to specify a custom USB VID/PID and a CPP definition.
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After reading a lot of forums posts and code,
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I discovered I could easily do this with `arduino-builder`,
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with the `-prefs=` flag.
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This allows you to override settings in `boards.txt`,
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which is apparently what Arduino uses to build a gcc flags list.
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Here's a trimmed-down version of what I implemented:
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```sh
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mkdir -p build/cache
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arduino-builder \
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-build-path $(pwd)/build/ \
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-build-cache $(pwd)/build/cache/ \
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-fqbn arduino:avr:leonardo \
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-hardware /usr/share/arduino/hardware/ \
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-tools /usr/share/arduino/tools/ \
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-prefs="build.extra_flags=-DUSB_VID=0x1bad -DUSB_PID=0x0004 -DCDC_DISABLED" \
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-compile MockBand.ino
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```
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---
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My final step was to write a `Makefile` to do all this.
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Since the build step is just one (long) command,
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and the `-prefs` could easily use per-target variables,
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`make` was an obvious tool.
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Adding a target to run `avrdude` was simple enough, too.
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I no longer need the Arduino IDE at all,
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but the project still works with it!
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The result was a
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[Makefile](https://git.woozle.org/neale/mockband/src/commit/63bd0672500631b8c47f24f041693e642ab32533/Makefile)
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which can compile, flash, and package
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all three variants of the build.
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It's 43 lines long,
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including blank lines.
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