feat: drive OLED with a testable screen-content model (PR 3/9) - #38
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Adds the SSD1306 OLED per PCB/README.md's hardware table (128x64, I2C). Split the same way as the rest of this rewrite: ScreenBuffer (screen.h/.cpp) is pure content — just a small grid of text lines, fully unit tested — and OledDisplay (oled.cpp) is a thin adapter over Adafruit_SSD1306/GFX that draws whatever a ScreenBuffer holds. Later PRs (menu, complications, gesture feedback) drive the display by changing ScreenBuffer content, never by touching the display directly. oled.cpp is hardware-touching (I2C/Adafruit_SSD1306) and has no branching logic worth testing, so it's excluded from native build/coverage the same way SnipsController.ino already is — extended platformio.ini's build_src_filter and ci.yml's gcovr --exclude to match. For now SnipsController.ino just shows a static boot message — real content lands with the menu/complications PRs. Flagged two assumptions in oled.h for real-hardware bring-up: the module's I2C address (0x3C) and that it needs no dedicated reset pin — neither is documented in the PCB docs. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
This was referenced Sep 7, 2026
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Summary
PR 3 of the firmware rewrite (PR 1: #35, PR 2: #36). Adds the SSD1306 OLED per
PCB/README.md's hardware table (128x64, I2C on pins 8/9).ScreenBuffer(include/screen.h/src/screen.cpp): pure content model — a small grid of text lines (8 rows x 21 cols, sized for the default 6x8px GFX font on this display), fully unit tested. Decides what text should be shown; knows nothing about I2C or Adafruit.OledDisplay(include/oled.h/src/oled.cpp): thin adapter wrappingAdafruit_SSD1306/GFX — draws whatever aScreenBuffercurrently holds. No content decisions live here.ScreenBuffercontent — nothing after this PR should need to toucholed.cppdirectly.oled.cppis hardware-touching with no branching logic worth testing, so it joinsSnipsController.inoin the native build/coverage exclusion list (platformio.ini+ci.yml, both updated).include/oled.hfor real-hardware bring-up, since neither is documented in the PCB docs: the module's I2C address (assumed0x3C) and that it needs no dedicated reset pin.For now
SnipsController.inojust shows a static boot message on the two top lines — real content lands with the menu/complications PRs.Test plan
pio test -e native— all 24 test cases passgcovr --exclude 'src/SnipsController\.ino' --exclude 'src/oled\.cpp' --fail-under-line 90— 100% acrossbuttons.cpp/power_latch.cpp/screen.cpppio run -e esp32s3— builds successfully, Adafruit SSD1306/GFX libs resolve and link0x3D(seeinclude/oled.h)🤖 Generated with Claude Code