CaspaPX
The MT9V032 sensor at the heart off the CaspaPX is not yet supported in the kernel, so a little work is necessary to get the camera up and running.
The OMAP35X processors have dedicated hardware for capturing and processing data from image sensors. The CaspaPX camera sensor outputs raw 10-bit Bayer images which is transfered to the Image Signal Processor (ISP) via a parallel interface. The ISP contains various submodules that can be exported as V4L2 devices in /dev. For additional hardware information see the external links section.
TODO: include a photo taken with the camera
Contents
Quickstart
The first steps are important to verify your hardware setup and to test your customizations later.
Install Pre-built Kernel
The easiest way to get started is to replace the kernel and modules of an existing image. This method was tested on an Overo Fire with a Tobi expansion board using the desktop image available here.
Get the kernel and modules.
$ mkdir ~/caspakernel $ cd ~/caspakernel $ wget cumulus.gumstix.org/images/caspapx/uImage $ wget cumulus.gumstix.org/images/caspapx/lib.tar.gz
Extract the modules.
$ tar -xf lib.tar.gz
Copy them to an Overo already running the image that you want.
$ scp lib/* root@overo:/lib/ $ scp uImage root@overo:/boot/uImage; $ scp uImage root@overo:/media/mmcblk0p1/uImage
Reset the overo.
$ ssh root@overo 'shutdown -r now'
This method is especially convenient for making modifications to the driver or kernel. See the customization section for more information.
Test
From the serial console:
# export -DISPLAY :0.0
# gst-launch v4l2src ! xvimagesink <or> # mplayer tv:// -tv driver=v4l2:device=/dev/video0
From the desktop:
<left-click on desktop> Applications > Multimedia > Cheese
If video0 doesn't appear in /dev you might have to load the driver manually.
# depmod # modprobe omap34xxcam # modprobe mt9v032
Bitbake
TODO: make a recipe, give the command to build it here and link to an article about creating/modifying recipes
Customization
This section describes how to customize the camera driver and kernel for your needs.
2.6.34
Get the kernel source that is used in the Gumstix kernel recipe (~/overo-oe/org.openmebedded.dev/recipes/linux/linux-omap3_2.6.34.bb) and create a new branch from the recipe SRCREV.
$ cd ~ $ git clone git://www.sakoman.com/git/linux-omap-2.6.git $ cd linux-omap-2.6 $ git checkout -b 2.6.34 cb89736af28f583598e49a05249334a194d00f1d
Get the patch
$ wget http://cumulus.gumstix.org/sources/mt9v032-2.6.34.patch $ patch -p1 < mt9v032-2.6.34.patch
Make a copy of the default kernel configuration to use as a starting point for your customizations.
$ cp ~/overo-oe/org.openembedded.dev/recipes/linux/linux-omap3-2.6.34/overo/defconfig ./ $ cp defconfig .config
Add the cross compiler to your path and configure the kernel
$ export PATH=/home/username/overo-oe/tmp/sysroots/i686-linux/usr/armv7a/bin:${PATH} $ make ARCH=arm menuconfig
Ensure that the following modules are enabled
-> System Type -> OMAP34xx Based System -> Device Drivers -> Multimedia support (must be built-in) -> Video For Linux (must be built-in) -> Video capture adapters (must be built-in) -> SoC camera support -> OMAP 3 Camera support -> mt9v032 support
Build kernel and modules
$ make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- uImage $ make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- modules
Install modules
$ mkdir ~/linux-omap-2.6/modules $ make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- INSTALL_MOD_PATH=./modules modules_install
Other Kernel Versions
The ISP code used for the 2.6.34 patch came from the arago-project. This is the OMAP3 PSP kernel integration/staging tree
$ git remote add git://arago-project.org/git/projects/linux-omap3.git aragoOMAP3 PSP kernel integration/staging tree $ git fetch arago $ git checkout -b arago
The V4L2 subdevice framework offers a way to configure the Image Signal Processor pipeline from userspace. This is currently under active development and users wishing to make use of this should visit the Media controller development repository here. This contains the bleeding edge Video for Linux media framework, ISP, and MT9V032 drivers.
MT9V032 Driver
If you want to take advantage of an unimplemented sensor feature, change defaults, etc., you need to modify the driver source. First, make sure that you change your kernel configuration to build the MT9V032 as a module unless you're only making a minor change. This will allow you to test your changes
Here is a convenient script for updating the driver after you've made a change:
#! /bin/bash
make -j8 ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- modules ssh root@overo 'rmmod mt9v032' scp drivers/media/video/mt9v032.ko root@10.0.1.15:/lib/modules/2.6.34/kernel/drivers/media/video/ ssh root@overo 'modprobe mt9v032'
Image Signal Processor
There is some code that you can't modularize and modifying means rebuilding the kernel. Such is the case for the ISP code which is used by board-overo.c for hardware configuration. Another script like that in the previous section can be very useful.
This script rebuilds the kernel, copies it to the COM, and resets:
#! /bin/bash
target_overo="root@10.0.1.15" make -j8 ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- uImage; scp arch/arm/boot/uImage $target_overo:/boot/uImage; scp arch/arm/boot/uImage $target_overo:/media/mmcblk0p1/uImage ssh $target_overo 'shutdown -r now'
TODO: discuss where previewer constants are and how they affect the output image