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C778 on Raspberry Pi 5B

This guide describes the one HDMI input → two CSI half-frame paths → host-side stitching profile. Each path carries 960×1080 @ 120 fps, forming a complete 1920×1080 image after correct pairing. Verify left/right ordering and colors before measuring frame rate.

Scope of the existing software

The available factory-test bundle requires the exact kernel 6.18.39+rpt-rpi-2712. It is not a universal installer for every Raspberry Pi image. Production driver source, installer and firmware-version mapping are being organized. The commands below apply to an already configured development environment or the matching test bundle, not an arbitrary clean system.

Hardware and environment​

  • Raspberry Pi 5B, host power supply, cooling and a bootable 64-bit Linux system with terminal access.
  • C778, its dedicated 5V lead and two verified compatible 22-pin FPC cables.
  • An HDMI source and cable supporting the target timing. Begin with static text/color bars, then use motion video.
  • Both CAM/DISP ports available for C778; stop other camera and capture applications.

Pi 5 has two four-lane MIPI ports labeled CAM/DISP 0 and CAM/DISP 1; see the official Raspberry Pi connector description. Verify module pinout, FPC contact orientation and host pins together.

Wiring​

  1. Turn off both devices and check power polarity and FPC orientation against the C778 connector reference.
  2. For split operation, connect both C778 MIPI outputs to the two Pi CAM/DISP ports. The existing factory-test convention is P3=LEFT→CSI0 and P1=RIGHT→CSI1. This internal naming must still be mapped explicitly to C778's MIPI0/MIPI1 silkscreen using the actual wiring.
  3. Connect I²S separately if audio is needed; the video factory test does not verify recording.
  4. Connect the HDMI source, supply C778 with 5V, then boot the Pi.

Do not infer left/right paths from cable color or fixed /dev/videoX numbers. Identify the media entities and actual image halves, then record their correspondence.

Inspect the system and capture paths​

Run on the Pi:

uname -m
uname -r
uname -v
cat /proc/device-tree/model
v4l2-ctl --list-devices
for media in /dev/media*; do
  [ -e "$media" ] || continue
  media-ctl -d "$media" -p
done

v4l2-ctl and media-ctl are normally provided by v4l-utils; on Raspberry Pi OS they can be installed from the system package repositories. The factory-test bundle carries its own runtime tools.

The existing test stack uses anran_lt6911uxe, anran_rp1_cfe and a dedicated DTBO. Loading the bridge module alone does not establish a working host CSI path. Discover two distinct capture paths and verify consistent pad and video-queue formats.

Existing factory-test bundle​

Obtain the complete matching uxe-factory-test folder from support and preserve all files and executable permissions. The bundle can deploy test modules and boot configuration. Back up boot configuration first. Investigate existing camera/driver conflicts rather than forcing an overwrite.

The current bundle requires:

CheckExact value
Architectureaarch64 / BCM2712
Kernel6.18.39+rpt-rpi-2712
Build#1 SMP PREEMPT Debian 1:6.18.39-1+rpt1 (2026-07-29)
/sys/kernel/notes SHA-256b552b3ec76cc19236e62f85f613db2ef61c213ff9de1d45da5e0cd5fb6caa987
# Verify first. Do not load bundled modules on a mismatched kernel.
uname -r
uname -v
sha256sum /sys/kernel/notes

# Run only on the matching target Pi.
cd ~/uxe-factory-test
sudo ./test
  • REBOOT_REQUIRED: deployment completed; capture has not passed. Reboot manually with sudo reboot, then run sudo ./test again from the same folder.
  • PASS: this particular run passed the bundle's concurrent capture checks.
  • KERNEL_BUILD_MISMATCH: stop; do not force-load modules.
  • Other failures: keep the report and logs in the corresponding results/<run-directory>/.

Do not blindly downgrade to an old kernel to match a test bundle, or assume historical package versions remain available. A production release should provide a reproducible source build or matching system image.

To revert configuration added by the bundle:

cd ~/uxe-factory-test
sudo ./test --restore
# Reboot manually if requested.

Verify image content​

A passing data-path test still needs content checks:

  1. Color bars and text: exclude RGB/BGR swaps, mirroring and exchanged channels.
  2. Stitching boundary: confirm a 1920×1080 image with no missing or repeated columns.
  3. Motion or a source frame counter: verify both halves come from the same source frame; independent fps readings are insufficient.
  4. HDMI disconnection/reconnection, resolution changes and reboot recovery.

The existing desktop preview script limits its output to 60 fps. It can help inspect image content but cannot prove 120 fps display or encoding performance.

Keep acceptance evidence​

Record host and module revisions, system/kernel, driver commit, DTBO and firmware hashes, input timing, both capture formats, measured fps, sequence/timestamps, color and synchronization checks, test duration and kernel errors.

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