YUV Sensor

Camera Package And Specification

The YUV camera DTB for Genio 1200-EVK is CAM DTB-D6. It contains Onsemi AP1302 ISP and AR0830 Sensor.

Camera DTB D6 - Onsemi AP1302 ISP and AR0830 Sensor

Connect The Camera To The EVK

There are 3 MIPI-CSI slots on Genio 1200-EVK, which are CSI0, CSI1, and CSI2. In the following figure, the camera DTB is connected to the CSI0 slot.

Connect Camera DTB D6 to Genio 1200-EVK (Schematic)

Connect Camera DTB D6 to Genio 1200-EVK (Entity)

Note

All three CSI slots are available. The user can connect the camera sensor to any slot.

Select Camera Device Tree Blob Overlay

The camera is inactive by default. The kernel has to load a specific device tree blob overlay to enable the camera. Please refer to bl33u-boot for more details.

Platform	Camera DTBO	Description
Genio 1200-EVK	camera-ar0830-ap1302-2lanes-csi0.dtbo	CAM-DTB-D6 w/ Onsemi AR0830 sensor, connected to CSI0, use 2-lane MIPI CSI
Genio 1200-EVK	camera-ar0830-ap1302-csi0.dtbo	CAM-DTB-D6 w/ Onsemi AR0830 sensor, connected to CSI0, use 4-lane MIPI CSI
Genio 1200-EVK	camera-ar0830-ap1302-csi1.dtbo	CAM-DTB-D6 w/ Onsemi AR0830 sensor, connected to CSI1, use 4-lane MIPI CSI
Genio 1200-EVK	camera-ar0830-ap1302-csi2.dtbo	CAM-DTB-D6 w/ Onsemi AR0830 sensor, connected to CSI2, use 4-lane MIPI CSI

genio-flash --list-dtbo
List of available DTBO:
        - camera-ar0830-ap1302-2lanes-csi0.dtbo
        - camera-ar0830-ap1302-csi0.dtbo
        - camera-ar0830-ap1302-csi1.dtbo
        - camera-ar0830-ap1302-csi2.dtbo
        - ...
genio-flash --load-dtbo camera-ar0830-ap1302-csi0.dtbo --load-dtbo gpu-mali.dtbo --load-dtbo apusys.dtbo --load-dtbo video.dtbo

Warning

Please select the DTBO according to the CSI slot to which the camera sensor is connected. For example, if the camera is connected to the CSI0 slot, please load the dtbo camera-ar0830-ap1302-csi0.dtbo. Otherwise, the camera initialization will fail.

Supported Formats And Sizes

Platform	Sensor	Stream Type	Size	Framerate	Format	MIPI Lanes
Genio 1200-EVK	Onsemi AP1302 & AR0830	Preview	1920x1080	30	UYVY	4
Genio 1200-EVK	Onsemi AP1302 & AR0830	Preview	2560x1440	30	UYVY	4
Genio 1200-EVK	Onsemi AP1302 & AR0830	Preview	3840x2160	24	UYVY	4
Genio 1200-EVK	Onsemi AP1302 & AR0830	Preview	1920x1080	30	UYVY	2
Genio 1200-EVK	Onsemi AP1302 & AR0830	Preview	2560x1440	30	UYVY	2
Genio 1200-EVK	Onsemi AP1302 & AR0830	Preview	3840x2160	12	UYVY	2

Note

The supported format, resoulution, and framerate are related to the capability of the sensor and SoC.

V4L2 Device Node

Camera ISP is a complicated feature that has a large number of device nodes. The camera ISP driver creates 123 video devices in total.

• MTK-ISP-DIP-V4L2 has 68 devices

• mtk-cam has 54 devices

• mtk-v4l2-camera has 1 device

MTK-ISP-DIP-V4L2 and mtk-cam are used by the camera ISP middleware. The user can just focus on mtk-v4l2-camera which is for streaming.

v4l2-ctl --list-devices
...
MTK-ISP-DIP-V4L2 (platform:15000000.imgsys_fw):
        (68 video devices)
        /dev/media0

mtk-cam (platform:16000000.camisp):
        (54 video devices)
        /dev/media2

mtk-v4l2-camera (platform:mtkcam0):
        /dev/video74

Launch Camera

The V4L2 nodes with the name mtk-v4l2-camera can be used for streaming. For the YUV sensor, there’s only 1 V4L2 device which is for the preview stream. The user can find the devices by the following command:

v4l2-ctl --list-device
mtk-v4l2-camera (platform:mtkcam0):
        /dev/video74
cat /sys/class/video4linux/video74/name
mtk-v4l2-camera@0-Preview

Important

The above v4l2 device node number is for example. The node number may change every time the system boots.

To quickly fetch the correct node and assign the environment variable:

declare -a video=(`v4l2-ctl --list-devices | grep mtk-v4l2-camera -A 1 | grep video | tr -d "\n"`)
printf "Preview Node\t= ${video[0]}\n"
Preview Node    = /dev/video74

Section Supported formats and Sizes shows the supported formats and sizes. The user can also use the v4l2 utility, v4l2-ctl, to list formats.

v4l2-ctl -d ${video[0]} --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture Multiplanar

        [0]: 'UYVY' (UYVY 4:2:2)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.033s (30.000 fps)
        ...

To launch the camera, the user can use v4l2-ctl, gst-launch-1.0, or other V4L2 applications.

• Use v4l2-ctl

  v4l2-ctl -d ${video[0]} --set-fmt-video=width=1920,height=1080,pixelformat=UYVY --stream-mmap --stream-count=10 --stream-to=/tmp/ap1302.yuv --verbose
  

• Use gst-launch-1.0

  gst-launch-1.0 v4l2src device=${video[0]} ! video/x-raw,width=1920,height=1080,format=UYVY ! v4l2convert output-io-mode=dmabuf-import ! video/x-raw,width=1280,height=720 ! waylandsink sync=false
  

  

  Show Preview stream on Weston

Note

To use MediaTek video codec and mdp hardware, the user needs to load video.dtbo. For more details, please refer to Genio 1200-EVK Video Codec.

Sensor Launch Time

In our camera operation sequence, we follow the steps below:

• Open Camera

  1. Power on the sensor

  2. Release the reset pin

  3. Configure the sensor settings

  4. Stream on the sensor

• Close Camera

  1. Stream off the sensor

  2. Hold the reset pin

  3. Power off the sensor

When using the AP1302 ISP, it is necessary to download a specific firmware binary during initialization. The launch time of the camera depends on the size of the binary file. The log provided below illustrates the start-up process of the AP1302 ISP and displays the corresponding launch time.

The presented log provides an overview of the AP1302 ISP start-up process and focuses on the launch time, which primarily measures the duration it takes to transmit the firmware through I2C at a speed of 400KHz.