AR0822 kernel driver for Raspberry Pi

Raspberry Pi kernel driver for Onsemi AR0822, an 8 MP rolling shutter 1/1.8" back side illuminated CMOS sensor.

• 2-lane and 4-lane MIPI CSI-2 (up to 960 Mbps/lane)
• 10-bit and 12-bit RAW output
• 3840×2160 @ 40 fps (full resolution)
• 1920×1080 @ 120 fps (2×2 binning)

AR0822 camera modules are available at kurokesu.com

Note

This driver supports an experimental eHDR mode, modeled after IMX708 implementation, by exposing the standard V4L2_CID_WIDE_DYNAMIC_RANGE control. Read more in eHDR (experimental).

Install

Connect camera to CSI port with Pi powered off.

Update OS and reboot:

sudo apt update && sudo apt full-upgrade -y
sudo reboot

Important

If driver or camera stack was previously built from source, run one-time cleanup before first apt install. See migrating from a source install.

Enable Kurokesu apt archive (skip if already enabled):

curl -fsSLO https://apt.kurokesu.com/setup.sh
sudo sh setup.sh

Install driver and camera stack:

sudo apt update
sudo apt install -y ar0822-rpi-dkms rpicam-apps

With archive enabled, apt resolves Kurokesu rpicam-apps and libcamera forks with AR0822 support as updates to stock packages. Later updates arrive with regular apt upgrade.

Edit boot configuration:

sudo nano /boot/firmware/config.txt

Make two changes:

1. Find camera_auto_detect near the top and set it to 0:

camera_auto_detect=0

2. Add dtoverlay=ar0822 under the [all] section at the bottom of the file:

[all]
dtoverlay=ar0822

If camera is connected to cam0 port, use dtoverlay=ar0822,cam0 instead. See cam0.

Save and exit.

config.txt changes take effect after reboot:

sudo reboot

Verify camera is detected:

rpicam-hello --list-cameras

Expected output (varies by lane configuration):

Available cameras
-----------------
0 : ar0822 [3840x2160 12-bit GRBG] (/base/axi/pcie@1000120000/rp1/i2c@88000/ar0822@10)
    Modes: 'SGRBG10_CSI2P' : 1920x1080 [120.15 fps - (0, 0)/3840x2160 crop]
                             3840x2160 [40.03 fps - (0, 0)/3840x2160 crop]
           'SGRBG12_CSI2P' : 1920x1080 [120.21 fps - (0, 0)/3840x2160 crop]
                             3840x2160 [33.89 fps - (0, 0)/3840x2160 crop]

Start live preview:

rpicam-hello -t 0

On headless systems, capture a still image instead:

rpicam-still -o test.jpg

dtoverlay options

ar0822 overlay supports comma-separated options to override defaults:

option	description	default
cam0	Use cam0 port instead of cam1	cam1
4lane	Use 4-lane MIPI CSI-2 (if wired)	2 lanes

cam0

If camera is connected to cam0 port, append ,cam0:

dtoverlay=ar0822,cam0

4lane

To enable 4-lane MIPI CSI-2, append ,4lane:

dtoverlay=ar0822,4lane

Warning

Before using 4lane, confirm your camera port actually supports 4-lane MIPI CSI. Not all Raspberry Pi models and carrier boards provide 4-lane MIPI CSI on both ports.

Tip

Options can be combined. Example (cam0, 4-lane):

dtoverlay=ar0822,cam0,4lane

eHDR (experimental)

AR0822 features an on-sensor HDR mode that expands dynamic range up to 120 dB by combining three exposures within sensor using the MEC algorithm. To reduce bandwidth requirements, linearized 20-bit HDR signal is companded to a 12-bit output.

Important

libcamera pipeline is designed for linear image data from sensor. Kurokesu's fork HDR implementation is experimental. Companded data may show color shifts due to compression.

Due to exposure range limitations, running at maximum fps with current PIXCLK configuration reduces maximum exposure drastically.

For instance, running 4K @ 30 fps results in maximum exposure T1 ≈ 10.26 ms, while running 4K @ 28.8 fps results in T1 ≈ 30.4 ms (right at internal delay buffer limit).

Consider reducing framerate slightly when larger exposure range is desired. This will be addressed in future driver revisions.

eHDR mode is enabled by appending --hdr to rpicam commands.

List eHDR modes

rpicam-hello --list-cameras --hdr

Available cameras
-----------------
0 : ar0822 [3840x2160 12-bit GRBG] (/base/axi/pcie@1000120000/rp1/i2c@88000/ar0822@10)
    Modes: 'SGRBG12_CSI2P' : 1920x1080 [48.04 fps - (0, 0)/3840x2160 crop]
                             3840x2160 [30.01 fps - (0, 0)/3840x2160 crop]

Build from source

Install required tools:

sudo apt install -y git
sudo apt install -y --no-install-recommends dkms

Clone this repository:

cd ~
git clone https://github.com/Kurokesu/ar0822-rpi-driver.git
cd ar0822-rpi-driver/

If driver was installed from apt archive previously, remove it first:

sudo apt remove ar0822-rpi-dkms

Run setup script:

sudo ./setup.sh

Camera stack, boot configuration and verification follow Install. Skip ar0822-rpi-dkms there, only rpicam-apps is needed. To build libcamera and rpicam-apps from source as well, see libcamera/BUILDING.md.

Migrating from a source install

One-time cleanup before first apt install.

Remove ar0822 driver modules installed by setup.sh:

dkms status | grep ar0822 | cut -d, -f1 | sort -u | xargs -rI{} sudo dkms remove {} --all

Source-built libcamera and rpicam-apps install to /usr/local and shadow packaged binaries. Remove them:

Warning

Command below deletes everything under /usr/local with libcamera, rpicam or libpisp in its name, including custom scripts or files named after them.

sudo find /usr/local -depth \( -name '*libcamera*' -o -name '*rpicam*' -o -name '*libpisp*' \) -exec rm -rf {} +

Cleanup complete. Continue with install steps.

Special thanks

• Will Whang for imx585-v4l2-driver, used as basis for structuring this driver.
• Sasha Shturma's Raspberry Pi CM4 carrier with Hi-Res MIPI Display project. Install script adapted from cm4-panel-jdi-lt070me05000.