BlackMark
5afe29359c
The submodule replaces FetchContent and the unpinned forge fallback; LIBAVR_ROOT stays as the tandem-development override, the presets take the toolchain file from the submodule, and the Studio project's include path anchors there — correct by construction. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
59 lines
2.5 KiB
Markdown
59 lines
2.5 KiB
Markdown
# fantemp
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Temperature-controlled fan firmware (ATmega328P, 16 MHz), rewritten on
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[libavr](https://git.blackmark.me/avr/libavr): thermistor on ADC0 sampled
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free-running and averaged over 1000 conversions, fan on OC0B at 50 kHz,
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115200 Bd serial console (`help` lists the commands), temperature
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histogram persisted to EEPROM, watchdog-reset path into a boot-section
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bootloader.
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The Steinhart–Hart math of the legacy firmware (runtime doubles + libm
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log) is gone: the Beta equation and the cubic fan curve are evaluated
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consteval into flash tables — the firmware itself never touches floating
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point.
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libavr rides as the `libavr/` submodule, pinned to the commit this firmware
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builds against; `LIBAVR_ROOT` (cache or environment) overrides it for
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development against a working tree:
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```sh
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git submodule update --init libavr
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cmake --preset atmega328p-generated
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cmake --build --preset atmega328p-generated
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```
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## Atmel Studio
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`master` carries a Studio solution, so this branch does too: `ide/fantemp.atsln`
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builds the same firmware — byte-identical `.text` and `.data` to the CMake
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build — from the same sources, with the flags mirrored by hand.
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Studio finds libavr in the **submodule**, at
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`$(MSBuildProjectDirectory)\..\libavr\include` — correct by construction, and
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anchored to the project rather than written relative to the generated makefile,
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which runs from the configuration's output directory and would need a different
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number of `..`. Unlike the CMake build there is no `LIBAVR_ROOT` to point
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elsewhere: an environment variable set in a shell is not visible to Studio
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launched from the Start menu — which is what the submodule answers.
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It also needs a GCC 16.1 toolchain registered as flavour `avr-g++-16.1.0`;
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nothing older can compile `-std=c++26`.
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One generated file is required before the project will load, and one command
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checks the flags have not drifted (both from libavr's `tools/atmelstudio/`):
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```sh
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python ../libavr/tools/atmelstudio/componentinfo.py \
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ide/fantemp.componentinfo.xml --device ATmega328P
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python ../libavr/tools/atmelstudio/check-flags.py --solution ide/fantemp.atsln \
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--compile-commands build/atmega328p-generated/compile_commands.json \
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--log build/atmelstudio.log
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```
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CMake remains the build system; the solution is there so the project opens in
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Studio as its predecessor did. Only the Release configuration is gated against
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CMake — the presets define no debug build — and Debug carries the `-Og
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-gdwarf-4` pair libavr's own debug preset uses.
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Legacy (yazoalfa submodules) stays on `master`.
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