Replace mipidsi with a direct port of pico/main.py's ST7796 driver (per-command CS,
MADCTL 0x48, INVON, no offset, big-endian RGB565) — fixes the geometry/colour mangling.
Render the UI into a 300KB RAM framebuffer (embedded-graphics), then push only the
full-width row bands that changed vs the last frame (FNV row-diff) — flicker-free and
~144/480 rows per playhead step. Full-width windows only: the panel's MX bit mirror-maps
sub-width windows wrongly (that was the black screen). SPI 62.5 MHz per pico-cp to shrink
the tearing window (no TE pin is routed on this board, so hardware vsync isn't available).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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