Camera interface

On this page you will find useful informations on how to use the Camera/CMOS Sensor Interface (CSI/CSI2) of the i.MX chip found on your APF and OPOS93Dev board. Currently only the APF27, APF6 & OPOS93 are supported.

Hardware

APF27

• All the signals of the i.MX27 CSI interface can be found on the J9 connector of the APF27Dev development board.
• You should connect an external camera/sensor compatible with the CSI interface (8bits data bus) to see something ;-). Here are the tested sensor models:
  • OV9653 / OV9655
  • OV7670
  • OV3640
• All these sensors are controllable through an I2C interface. The one on J8 connector of APF27Dev can for example be used.

APF6

• APF6Dev boards have a wandcam (OV5640) compatible connector (near the PCIexpress one).
• MIPI bus is used on APF6Dev

OPOS93

• The OPOS93DEV board has a 15-pin Raspberry Pi Camera compatible connector (located below the OPOS93 SoC).
• A 2-lane MIPI CSI-2 bus is used.
• Tested with the OmniVision OV5647 sensor.

Driver

• From now we consider that you have a supported camera module plugged on your development board
• CSI interface can be driven through the V4L2 (Video For Linux) standard interface as soon as CSI/MIPI driver is loaded:

APF27	APF6 (kernel 3.19+)
# modprobe mx27_camera Then you have to load your camera driver in order for him to "attach" to the CSI one (for example for the OV9653): # modprobe ov96xx	# modprobe -a mx6-camera mipi-csi2 ov5640-mipi

• On OPOS93, the driver is automatically loaded when the camera is connected.
• Now it's up to you to configure your camera with the tools/API the camera driver is offering...

Test

• We have a small SDL/V4L2 app to quickly test that your camera is working properly (you will also need a LCD interface): target/demos/camera/capture/
  • it may be installed by default on your rootfs depending on your Buildroot defconfig.
  • to launch it (here to have a 640x480 camera image on a LW700 TFT):

# capture --width 640 --height 480 --cam_width 640 --cam_height 480

• To trigger autofocus (APF6 with 3.19+ kernel):

# v4l2-ctl -c auto_focus_start=1

• On OPOS93DEV, the pipeline must have the same configuration on every link in the pipeline.
• Let's create a script:

# cat << EOF >> setCam.sh && chmod +x setCam.sh

SOURCE=$3
FORV4L2=$4
XL=$1
YL=$2

if [[$SOURCE == ""]]; then
        SOURCE=SBGGR10_1X10
fi
if [[$FORV4L2 == ""]]; then
        FORV4L2=BG10
fi
if [[$XL == ""]]; then
        XL=640
        YL=480
fi

BAYER=$SOURCE/$XL\x$YL
echo Setting format to $XL/x$YL in $SOURCE - $FORV4L2
media-ctl -v -V "'csidev-4ae00000.csi':0 [fmt:$BAYER field:none]"
media-ctl -v -V "'csidev-4ae00000.csi':1 [fmt:$BAYER field:none]"
media-ctl -v -V "'mxc_isi.0':0 [fmt:$BAYER field:none]"
media-ctl -v -V "'mxc_isi.0':1 [fmt:$BAYER field:none]"
media-ctl -v -V "'crossbar':0 [fmt:$BAYER field:none]"
media-ctl -v -V "'crossbar':2 [fmt:$BAYER  field:none]"
media-ctl -v -V "'ov5647 2-0036':0 [fmt:$BAYER field:none]"
media-ctl -l "'ov5647 2-0036':0 -> 'csidev-4ae00000.csi':0[1]"
v4l2-ctl -d /dev/video0 --set-fmt-video=width=$XL,height=$YL,pixelformat=$FORV4L2
v4l2-ctl -d /dev/v4l-subdev3 -c exposure=855
v4l2-ctl -d /dev/v4l-subdev3 -c gain_automatic=1
v4l2-ctl -d /dev/v4l-subdev3 -c auto_exposure=0
v4l2-ctl -d /dev/v4l-subdev3 -c white_balance_automatic=1
> EOF 

• Run your script (if you put some arguments, remember the entire pipeline must have the same configuration) and check that all pads have the same format.

# .setCam.sh
#  media-ctl -p

• Try streaming to the framebuffer.

# gst-launch-1.0 --no-position v4l2src ! 'video/x-bayer,format=bggr10le,width=640,height=480,bpp=10,framerate=(fraction)10/1' ! bayer2rgbneon reduce-bpp=t show-fps=t silent=t ! fbdevsink device=/dev/fb0

Going further

• Using the i.MX27 video codec

Links

• Video4Linux