48 lines
1.8 KiB
Markdown
48 lines
1.8 KiB
Markdown
# Dasung Paperlike display
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FDS includes `dasungd` for the configured Dasung Paperlike 13K grayscale monitor.
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The controller starts during early boot and remains supervised in the base system,
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including console-only use. No GUI or ENVIRONMENT cartridge is required.
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The supplied profile uses the dedicated monitor's EDID and USB companion identity,
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with raw mode 1 and contrast 4 as startup defaults. It is specific to that monitor;
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do not use its identity as a blanket match for other CH340 USB devices.
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## Inspect the controller
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The controller's socket is restricted to root. From a root maintenance console
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on FDS:
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```sh
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dasungd status
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dasungd query
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```
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`status` reports whether the monitor is connected and responsive, the age of its
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last reply and cached parameters. `query` requests current values. To refresh
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the display or adjust contrast:
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```sh
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dasungd refresh
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dasungd set contrast 4
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dasungd set mode 1 --save
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dasungd forget mode
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```
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A successful set means the command was sent; use query/status to read back the
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result. The grayscale model uses raw numeric modes. Saved overrides in
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`/run/dasungd/settings.json` survive a daemon restart during the same boot, but
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not power loss. Image configuration defaults are in `/etc/dasungd.toml`.
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## Diagnose a connection problem
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Inspect `/run/log/dasungd/current` and the reported status. Discovery requires
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the configured DRM EDID and matching USB companion topology. An ambiguous match
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is rejected. Set `usb_path` only after identifying the intended device topology.
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FDS uses the daemon for USB control. Its configuration disables the original
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workstation-specific display hotplug procedure. Video mode and cabling are part
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of the machine's boot/display configuration. The detailed protocol, build
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rationale and physical display procedures are in the
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[developer reference](developer/dasung.md).
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