cberryfb

Linux framebuffer driver for the admatec C-Berry LCD module

installation (cross compile on Linux)

for other platforms or distribution specific info follow the instructions on http://elinux.org/RPi_Kernel_Compilation

setup the compiler

set the build directory. (you can change the path as you like)

export BUILD_DIR=~/pi

create the build directory.

mkdir $BUILD_DIR
cd $BUILD_DIR

download the pre-built bmc2708 compiler.

git clone git://github.com/raspberrypi/tools.git --depth 1

set the cross compiler prefix.

export CCPREFIX=$BUILD_DIR/tools/arm-bcm2708/arm-bcm2708-linux-gnueabi/bin/arm-bcm2708-linux-gnueabi-

get the kernel source

git clone --depth 1 git://github.com/raspberrypi/linux.git

configure the kernel

get the pi's current kernel config (execute on the pi).

ssh root@pi
zcat /proc/config.gz > /root/config
exit

you could use https://github.com/Hexxeh/rpi-update to update to the latest kernel. this way you might not have to update as much kernel options in the next step as with the older kernel. but it is really not necessary.

copy the config to your build directory (execute on the build machine)

scp root@pi:/root/config linux/.config

update the kernel config (make sure the above mentioned cross compiler prefix is exported)

cd $BUILD_DIR/linux
make ARCH=arm CROSS_COMPILE=${CCPREFIX} oldconfig

add cberryfb

get the cberryfb source

git clone https://github.com/u-voelkel/cberryfb.git drivers/video/cberryfb/

append to drivers/video/Makefile

obj-$(CONFIG_FB_CBERRY)       += cberryfb/

append to drivers/video/Kconfig (before endmenu)

source "drivers/video/cberryfb/Kconfig"

select the driver

make ARCH=arm CROSS_COMPILE=${CCPREFIX} menuconfig
→ Device Drivers → Graphics support
<M> C-Berry LCD frame buffer support
Exit and save

note: you could also add the cberry sources before the make oldconfig step and then select the module when running it.

compile the kernel

simply run

make ARCH=arm CROSS_COMPILE=${CCPREFIX}
make ARCH=arm CROSS_COMPILE=${CCPREFIX} modules

if you have multiple cpus or cores you can use the -j option to make use of them. a rule of thumb is number of cpus/cores + 1. so on a dual core machine it would be

make -j 3 ARCH=arm CROSS_COMPILE=${CCPREFIX}

go get yourself a coffee or a sandwich. It might take some time.

install the kernel

first you should backup the existing kernel on the pi.

cd /boot
mv kernel.img kernel_old.img

copy the kernel to the pi.

scp $BUILD_DIR/linux/arch/arm/boot/zImage root@pi:/boot/kernel.img

install the modules

install the modules in a temporary directory.

export MODULES_TEMP=$BUILD_DIR/modules
mkdir $MODULES_TEMP
make ARCH=arm CROSS_COMPILE=${CCPREFIX} INSTALL_MOD_PATH=${MODULES_TEMP} modules_install

copy the modules to the pi

rsync --progress -a --no-l -vhe ssh $BUILD_DIR/modules/lib/ root@pi:/lib/

done

you are done. reboot the pi to use the new kernel.

shutdown -r now

usage

the module is called "cberryfb"

modprobe cberryfb
dmesg

the last line should look like this: fb1: admatec C-Berry LCD framebuffer device

run the X-server

FRAMEBUFFER=/dev/fb1 startx

note: you might need to remove the fbturbo driver first

apt-get remove xserver-xorg-video-fbturbo

mplayer

mplayer -nolirc -vo fbdev2:/dev/fb1 -vf scale=320:-3 video.mpg

display an image using fbi

fbi -d /dev/fb1 -T 1 -noverbose -a image.bmp

console

to map console 1 to fb1 execute

con2fbmap 1 1

to map console 1 back to fb0 execute

con2fbmap 1 0

backlight

You can control the backlight using the files under /sys/class/backlight/cberryfb/

cat /sys/class/backlight/cberryfb/actual_brightness
cat /sys/class/backlight/cberryfb/max_brightness

echo 100 > /sys/class/backlight/cberryfb/brightness
echo 0 > /sys/class/backlight/cberryfb/brightness
echo 255 > /sys/class/backlight/cberryfb/brightness