[Community] [News] GTA04 Camera

Dr. H. Nikolaus Schaller hns at goldelico.com
Tue Apr 9 18:46:35 CEST 2013


Hi,
the camera is finally starting to work!

Here is a short video made with the GTA04 camera:

	<http://youtu.be/lFWvVXThAGk>

Quality is not yet optimized and exact frame position isn't as well.

And the frame rate is quite limited by mplayer / mencoder running (unaccelerated?)
on the GTA04.

But I think we have reached a major milestone and I encourage to compile your own camera
driver and let us all know about patches and improvements.

Source of the V4L2 subdevice driver is here:

	<http://git.goldelico.com/?p=gta04-kernel.git;a=blob;f=drivers/media/i2c/ov9655.c;hb=HEAD>
	<http://git.goldelico.com/?p=gta04-kernel.git;a=blob;f=include/media/ov9655.h;hb=HEAD>

and of course the matching board file entries (to load and configure camera and ISP capture interface):

	<http://git.goldelico.com/?p=gta04-kernel.git;a=blob;f=arch/arm/mach-omap2/board-omap3gta04.c;hb=HEAD>

The working camera demo (only works as "camera-demo sxga") is here:

	<http://git.goldelico.com/?p=gta04-rootfs.git;a=blob;f=debian/config/root/camera-demo;hb=HEAD>

And frame capture by C code:

	<http://git.goldelico.com/?p=gta04-rootfs.git;a=blob;f=debian/config/root/capture.c;hb=HEAD>

Finally, the media-ctl comes as a precompiled (armel) debian package here:

	<http://download.goldelico.com/gta04/debian/dists/stable/main/binary-armel/>

So what is working?
* initialization
* capture interface
* SXGA resolution (specified for 15fps)
* capture through mplayer or C code
* media-ctl to set-up the OMAP3 ISP

What is not working?
* hsync/vsync position
* VGA, QVGA, CIF does not set pixel clock etc. correctly
* only understands UYVY although the camera can provide (raw or cooked) RGB
* frame rate (?)
* more settings (black/white level, AGC)
* flashlight driver and connection between drivers
* picture is a little speckled (green and magenta spots)
* the driver code still has spoils from the original driver it was forked from, i.e. needs code clean-up
* overclocking of the camera - it is specified to run up to 48 MHz which would theoretically allow 30fps @ SXGA

What were the key challenges?
* understanding how V4L2 subdevices work
* understanding that both the camera and the OMAP3 have a signal processor
* understanding the media-ctl command to bypass the OMAP3 ISP
* understanding format encoding in the kernel drivers

Happy experimenting!

Now as the basics are here, I am curious which distro will be the first to come with a camera application :)

Nikolaus




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