iMX6 TinyRex Camera

This example uses Raspberry Pi Camera Rev 1.3 (build on OV5647 MIPI sensor) as a test device for CSI Interface. On this page OV5647 sensor integration, settings and usage on i.MX6 processors are shown.

Note: There is an issue concerning Raspberry Pi 1.3 cameras and its I2C detected. There might be some models that does not get identified.

Device detection

Kernel 4.1

...
camera ov5647_mipi is found
...

Kernel 3.14

...
camera ov5647_mipi is found
mxc_v4l2_master_attach: ipu(0:0)/csi(1:0)/mipi(1:0) doesn't match
mxc_v4l2_master_attach: ipu0:/csi1 mipi attached ov5647_mipi:mxc_v4l2_cap1
ERROR: v4l2 capture: slave not found!
...

I2C detect

CSI connector uses I2C2 to communicate with cameras. OV5647 sensor is located at 0x36 address:

root@imx6s-tinyrex:~# i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- UU -- -- -- 3a -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

GPIO control

GPIO pins are controlled by the camera driver and access to these pins is blocked. Power on GPIO is 74, LED GPIO has number 54.

root@imx6s-tinyrex:~# modprobe -r ov5647_camera_mipi
root@imx6s-tinyrex:~# echo 54 > /sys/class/gpio/export
root@imx6s-tinyrex:~# echo out > /sys/class/gpio/gpio54/direction
root@imx6s-tinyrex:~# echo 1 > /sys/class/gpio/gpio54/value
root@imx6s-tinyrex:~# echo 0 > /sys/class/gpio/gpio54/value
root@imx6s-tinyrex:~# echo 54 > /sys/class/gpio/unexport
root@imx6s-tinyrex:~# modprobe ov5647_camera_mipi

Modules

Kernel 4.1

root@imx6-tinyrexmax:~# lsmod
Module                  Size  Used by
mxc_v4l2_capture       27624  2
ipu_bg_overlay_sdc      5385  1 mxc_v4l2_capture
ipu_still               2331  1 mxc_v4l2_capture
ipu_prp_enc             5903  1 mxc_v4l2_capture
ipu_csi_enc             3904  1 mxc_v4l2_capture
ipu_fg_overlay_sdc      6130  1 mxc_v4l2_capture
ov5647_camera_mipi_int    30566  0
adv7610_video           6373  0
v4l2_int_device         2872  4 ov5647_camera_mipi_int,adv7610_video,ipu_csi_enc,mxc_v4l2_capture
mxc_dcic                6528  0

Kernel 3.14

root@imx6s-tinyrex:~# lsmod
Module                  Size  Used by
mxc_v4l2_capture       28532  1 
ipu_bg_overlay_sdc      5401  1 mxc_v4l2_capture
ipu_still               2528  1 mxc_v4l2_capture
ipu_prp_enc             5943  1 mxc_v4l2_capture
ipu_csi_enc             3863  1 mxc_v4l2_capture
ipu_fg_overlay_sdc      6217  1 mxc_v4l2_capture
ov5647_camera_mipi     30906  0 
v4l2_int_device         2930  2 ov5647_camera_mipi,mxc_v4l2_capture
mxc_dcic                6569  0 
evbug                   1875  0

Resolution change

1280x960

echo 0 > /sys/bus/i2c/devices/1-0036/ov5647_mode

1280x720

echo 1 > /sys/bus/i2c/devices/1-0036/ov5647_mode

1920x1080

echo 2 > /sys/bus/i2c/devices/1-0036/ov5647_mode

640x480

echo 3 > /sys/bus/i2c/devices/1-0036/ov5647_mode

1024x768 (default)

echo 4 > /sys/bus/i2c/devices/1-0036/ov5647_mode

960x720

echo 5 > /sys/bus/i2c/devices/1-0036/ov5647_mode

=== 640x480 (narrow angle of view)

echo 6 > /sys/bus/i2c/devices/1-0036/ov5647_mode

Gstreamer

Capture single JPEG picture

echo 2 > /sys/bus/i2c/devices/1-0036/ov5647_mode
gst-launch-1.0 v4l2src device="/dev/video1" num-buffers=1 ! video/x-bayer,width=1920,height=1080,framerate=30/1 ! bayer2rgb ! videoconvert ! jpegenc ! filesink location=sample_1920_1080.jpeg

Video preview

echo 2 > /sys/bus/i2c/devices/1-0036/ov5647_mode
gst-launch-1.0 v4l2src device="/dev/video1" ! video/x-bayer,width=1920,height=1080,framerate=30/1 ! queue ! bayer2rgb ! videoconvert ! fbdevsin

echo 3 > /sys/bus/i2c/devices/1-0036/ov5647_mode
gst-launch-1.0 v4l2src device="/dev/video1" ! video/x-bayer,width=640,height=480,framerate=15/1 ! bayer2rgb ! videoconvert ! fbdevsink