guivi

sudo nano /boot/cmdline.txt
dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty3 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait loglevel=3 quiet logo.nologo

add "disable_splash=1" to /boot/config.txt
add "disable_overscan=1" to /boot/config.tx
------------------------------------------------------------------

place an image as splashscreen

install fbi: sudo apt install fbi 
Creat the service file:  /etc/systemd/system/splashscreen.service 
Edit the service file to have the following content:

[Unit]
Description=Splash screen
DefaultDependencies=no
After=local-fs.target

[Service]
ExecStart=/usr/bin/fbi -d /dev/fb0 --noverbose -a /opt/splash.png
StandardInput=tty
StandardOutput=tty

[Install]
WantedBy=sysinit.target

Change location of the image accordengly.
Enable the service: sudo systemctl enable splashscreen

Steps:

Install the lite version of raspbian and make it boot to console with autoogin.

sudo apt-get update -qq

sudo apt-get install --no-install-recommends xserver-xorg-video-all \
  xserver-xorg-input-all xserver-xorg-core xinit x11-xserver-utils \
  chromium-browser unclutter

# Go to: Boot Options > Console Autologin
sudo raspi-config

Next edit /home/pi/.bash_profile to automatically start the gui. There’s a check for the bash context first, so you don’t accidentally start chromium whenever you ssh in. This below may not be needed.

if [ -z $DISPLAY ] && [ $(tty) = /dev/tty1 ]
then
  startx
fi

The last bit is to setup /home/pi/.xinitrc to run chromium whenever you run startx. Here’s the full list of chromium arguments.

#!/usr/bin/env sh
xset -dpms
xset s off
xset s noblank

unclutter &
chromium-browser https://yourfancywebsite.com \
  --window-size=1920,1080 \
  --window-position=0,0 \
  --start-fullscreen \
  --kiosk \
  --incognito \
  --noerrdialogs \
  --disable-translate \
  --no-first-run \
  --fast \
  --fast-start \
  --disable-infobars \
  --disable-features=TranslateUI \
  --disk-cache-dir=/dev/null \
  --overscroll-history-navigation=0 \
  --disable-pinch

It disables the cursor and screensaver. Then runs chromium with *all* of the flags. Set https://yourfancywebsite.com to the website which you want to display. And set --window-size to the size of your display (it’s horizontal first and vertical after the comma).

You may also want to uncomment disable_overscan=1 in /boot/config.txt so that the pi boots up using the full display.

Now whenever the pi boots up it’ll go into the console then on into chromium. If you want to exit you can hit Alt+F4, then enter startx to start up the browser again.

omxplayer “rstp://user:pass@host:port/path/subpath” –avdict rtsp_transport:tcp –no-osd –live –with-info –stats;

Pre-requirements

Before you start you need to make sure the following is installed:

apt-get install git rsync cmake libc6-i386 lib32z1 lib32stdc++6

Let’s cross compile a Pie!

Start with making a folder in your home directory called raspberrypi.

Go in to this folder and pull down the ENTIRE tools folder you mentioned above:

git clone https://github.com/raspberrypi/tools.git

You wanted to use the following of the 3 ones, gcc-linaro-arm-linux-gnueabihf-raspbian, if I did not read wrong.

Go into your home directory and add:

export PATH=$PATH:$HOME/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin

to the end of the file named ~/.bashrc

Now you can either log out and log back in (i.e. restart your terminal session), or run . ~/.bashrc in your terminal to pick up the PATH addition in your current terminal session.

Now, verify that you can access the compiler arm-linux-gnueabihf-gcc -v. You should get something like this:

Using built-in specs. COLLECT_GCC=arm-linux-gnueabihf-gcc COLLECT_LTO_WRAPPER=/home/tudhalyas/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/../libexec/gcc/arm-linux-gnueabihf/4.7.2/lto-wrapper Target: arm-linux-gnueabihf Configured with: /cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.b uild/src/gcc-linaro-4.7-2012.08/configure –build=i686-build_pc-linux-gnu –host=i686-build_pc- linux-gnu –target=arm-linux-gnueabihf –prefix=/cbuild/slaves/oort61/crosstool-ng/builds/arm-l inux-gnueabihf-raspbian-linux/install –with-sysroot=/cbuild/slaves/oort61/crosstool-ng/builds/ arm-linux-gnueabihf-raspbian-linux/install/arm-linux-gnueabihf/libc –enable-languages=c,c++,fo rtran –disable-multilib –with-arch=armv6 –with-tune=arm1176jz-s –with-fpu=vfp –with-float= hard –with-pkgversion=’crosstool-NG linaro-1.13.1+bzr2458 – Linaro GCC 2012.08′ –with-bugurl= https://bugs.launchpad.net/gcc-linaro –enable-__cxa_atexit –enable-libmudflap –enable-libgom p –enable-libssp –with-gmp=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-rasp bian-linux/.build/arm-linux-gnueabihf/build/static –with-mpfr=/cbuild/slaves/oort61/crosstool- ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux-gnueabihf/build/static –with-mpc =/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux- gnueabihf/build/static –with-ppl=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf -raspbian-linux/.build/arm-linux-gnueabihf/build/static –with-cloog=/cbuild/slaves/oort61/cros stool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux-gnueabihf/build/static –wi th-libelf=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/a rm-linux-gnueabihf/build/static –with-host-libstdcxx=’-L/cbuild/slaves/oort61/crosstool-ng/bui lds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux-gnueabihf/build/static/lib -lpwl’ –ena ble-threads=posix –disable-libstdcxx-pch –enable-linker-build-id –enable-plugin –enable-gol d –with-local-prefix=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-li nux/install/arm-linux-gnueabihf/libc –enable-c99 –enable-long-long Thread model: posix gcc version 4.7.2 20120731 (prerelease) (crosstool-NG linaro-1.13.1+bzr2458 – Linaro GCC 2012.08 )

But hey! I did that and the libs still don’t work!

We’re not done yet! So far, we’ve only done the basics.

In your raspberrypi folder, make a folder called rootfs.

Now you need to copy the entire /liband /usr directory to this newly created folder. I usually bring the rpi image up and copy it via rsync:

rsync -rl –delete-after –safe-links pi@192.168.1.PI:/{lib,usr} $HOME/raspberrypi/rootfs

where 192.168.1.PI is replaced by the IP of your Raspberry Pi.

Now, we need to write a cmake config file. Open ~/home/raspberrypi/pi.cmake in your favorite editor and insert the following:

SET(CMAKE_SYSTEM_NAME Linux) SET(CMAKE_SYSTEM_VERSION 1) SET(CMAKE_C_COMPILER $ENV{HOME}/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc) SET(CMAKE_CXX_COMPILER $ENV{HOME}/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-g++) SET(CMAKE_FIND_ROOT_PATH $ENV{HOME}/raspberrypi/rootfs) SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER) SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY) SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

Now you should be able to compile your cmake programs simply by adding this extra flag: -D CMAKE_TOOLCHAIN_FILE=$HOME/raspberrypi/pi.cmake.

Using a cmake hello world example:

git clone https://github.com/jameskbride/cmake-hello-world.git cd cmake-hello-world mkdir build cd build cmake -D CMAKE_TOOLCHAIN_FILE=$HOME/raspberrypi/pi.cmake ../ make scp CMakeHelloWorld pi@192.168.1.PI:/home/pi/ ssh pi@192.168.1.PI ./CMakeHelloWorld

I have taken the above from stackoverflow:

https://stackoverflow.com/questions/19162072/how-to-install-the-raspberry-pi-cross-compiler-on-my-linux-host-machine

I did not managed to get the cmake to work as the pkg-config seem to have problems identifying where the libraries are and it was adding my libraries from teh host computer rather than the target ones. But following the same instructions it did worked fine when making my own call to the compiler and adding all the paths and libraries manually to the command.

This is a copy past from another person you can find the original blog here:
https://ep.gnt.md/index.php/how-to-clone-raspberry-pi-sd-card-on-linux-and-shrink-it-to-actual-size/
I am making a copy here is I can find it easy and in case the original disappear of the web.

On Linux you can use dd to make a backup from SD card. Reverse if and of (i.e. to where they point – source and destination) afterwards to restore, but be careful not to restore to a wrong disk. It will be destroyed without a warning!!!

First use fdisk to get the device id of you SD card (check the size)

fdisk -l

then use dd to make a diskimage (change /dev/sdb with what you found with fdisk -l):

dd bs=4M if=/dev/sdb of=image1-`date +%d%m%y`.img

or this to make a compressed image:

dd bs=4M if=/dev/sdb | gzip > image1-`date +%d%m%y`.img.gz

The process will take some time. After the image is created you will notice that it’s too big(size of a SD card). To shrink it we will use a perfect script that I found on github here https://github.com/Drewsif/PiShrink.git called PiShrink.

PiShrink is a bash script that automatically shrink a pi image that will then resize to the max size of the SD card on boot. This will make putting the image back onto the SD card faster and the shrunk images will compress better.

Installation

wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh
chmod +x pishrink.sh
sudo mv pishrink.sh /usr/local/bin

Usage example

$ sudo pishrink.sh pi.img
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/loop1: 88262/1929536 files (0.2% non-contiguous), 842728/7717632 blocks
resize2fs 1.42.9 (28-Dec-2013)
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/loop1 to 773603 (4k) blocks.
Begin pass 2 (max = 100387)
Relocating blocks             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 3 (max = 236)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 4 (max = 7348)
Updating inode references     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/loop1 is now 773603 blocks long.

Shrunk pi.img from 30G to 3.1G

Real time interrupts and operating systems are not generally compatible. For operating systems it is needed to poll the pin which one is willing to work as an interrupt but this is not real time and generally speaking is not very CPU deficient. For this purpose a Kernel module can be inserted which can handle this as real time as possible. I needed to make an interrupt in a raspberry pi to be able to count encoder signals, the following tutorial is the ins and outs of how I achieved this.

Firstly install the latest Raspbian (I have done this tutorial with Raspbian Stretch Lite) I will also mention here that I recommend using a none X server operating system as some of the print calls from kernel you may not see them if you are in a X server OS:
https://www.raspberrypi.org/downloads/raspbian/

Once downloaded you can burn the image to a micro SD card using DiskImager in windows:
https://sourceforge.net/projects/win32diskimager/

Then insert the SD card on the Raspberry PI (I used PI3) and boot from the micro SD card. Make sure the PI is connected to the internet.

In the command line run the following commands:

# The usual update routine

apt-get update -y
apt-get upgrade -y

# Update the kernel!

rpi-update

# Get rpi-source

sudo wget https://raw.githubusercontent.com/notro/rpi-source/master/rpi-source -O /usr/bin/rpi-source

# Make it executable

sudo chmod +x /usr/bin/rpi-source

# Tell the update mechanism that this is the latest version of the script

/usr/bin/rpi-source -q –tag-update

# Get the kernel files thingies.

rpi-source

At this point you should have all the needed components to start compiling a kernel module.

So lets start by looking at a simple Hello World kernel module:

# Create a new directory enter it.

mkdir hello
cd hello

# Crete a file named hello.c and edit it

nano hello.c

# Edit the file to have the following lines of code in it.

#include <linux/module.h>
#include <linux/kernel.h>

void hello_exit(void)
{
pr_alert(“Goodbye World!\n”);
}
module_init(hello_init);
module_exit(hello_exit);

# Save the file and exit nano

Ctrl+X (and follow the on screen options)

# Make a Makefile for compiling

nano Makefile

# Edit it as follow.

obj-m := hello.o

# save file and exit

Ctrl+X (and follow the on screen options)

# Compile and load kernel module

make -C /lib/modules/$(uname -r)/build M=$(pwd) modules
insmod hello.ko

That is it. You have mounted your first kernel module. it does nothing but it is a start.

——————————————————————————————————
——————————————————————————————————
————————- SOMETHING A BIT MORE COMPLICATED —————————
——————————————————————————————————
——————————————————————————————————

The interrupt module I made looks like this:

#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/uaccess.h>

module_init(rfrpi_init);
module_exit(rfrpi_exit);

The Makefile for it is as follow:

ifneq (${KERNELRELEASE},)
obj-m = krfrpi.o
else
KERNEL_DIR ?= /lib/modules/$(shell uname -r)/build
MODULE_DIR := $(shell pwd)

clean:
rm -f *.o *.ko *.mod.c .*.o .*.ko .*.mod.c .*.cmd *~
rm -f Module.symvers Module.markers modules.order
rm -rf .tmp_versions
endif

Once this module is mounted it makes a file at /dev/rfrpi this file can be dumped with cat /dev/rfrpi or you can read it in a c program as follow:

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>

}
close(fd);
return 0;
}

References:

Step by step on how to compile a kernel module:
https://raspberrypi.stackexchange.com/questions/39845/how-compile-a-loadable-kernel-module-without-recompiling-kernel#40419

Raspberry PI Interrupt example:
https://www.disk91.com/2015/technology/systems/rf433-raspberry-pi-gpio-kernel-driver-for-interrupt-management/

Article on Raspberry PI module kernel programming:
https://blog.fazibear.me/the-beginners-guide-to-linux-kernel-module-raspberry-pi-and-led-matrix-790e8236e8e9

Information on GPIO.h header file. Very good for general reference.
https://www.mjmwired.net/kernel/Documentation/gpio.txt

https://elixir.bootlin.com/linux/latest/source/include/linux/gpio.h

To build raspivid and only raspivid then the following command should do it (assuming your repo (https://github.com/raspberrypi/userland.git) clone is in ~/userland):

gcc -o myraspivid RaspiVid.c RaspiCamControl.c RaspiPreview.c RaspiCLI.c \ -I$HOME/userland -I$HOME/userland/host_applications/linux/libs/bcm_host/include \ -L/opt/vc/lib -lbcm_host -lvcos -lpthread -lmmal_core -lmmal_util -lmmal_vc_client

tested with

• RasPi 3B with Raspbian Jessie, IPv4 address 192.168.2.104
• Ubuntu 16.04 client, IPv4 address 192.168.2.108

raspivid options used:

live TCP streaming on RasPi

RasPi is listening (-l) and keeps (-k) listening after a TCP session terminated. RasPi’s own (local) IPv4 address is specified.

pi@raspberrypi:~ $ raspivid -t 0 -n -b 1000000 -g 30 -ih -pf baseline -w 640 -h 480 -fps 30 -l -o tcp://192.168.2.104:1234

Drawback: after client terminates, raspivid terminates too. So you might want to wrap it with an endless bash script loop

pi@raspberrypi:~ $ while :; do raspivid -t 0 -n -b 1000000 -g 30 -ih -pf baseline -w 640 -h 480 -fps 30 -l -o tcp://192.168.2.104:1234 ; done

remote client

Now, on remote client, vlc is opening and terminating TCP stream:

$ vlc -v tcp/h264://192.168.2.104:1234

UDP streaming remote client

Start remote client first, otherwise it could miss the H.264 SPS/PPS which are needed for decoding the stream. Client is waiting for incoming packets on UDP socket:

$ vlc -vvv udp/h264://@:1234

RasPi

RasPi is pushing UDP packets to the client.

without nc

pi@raspberrypi:~ $ raspivid -t 0 -n -b 1000000 -g 30 -ih -pf baseline -w 640 -h 480 -fps 30 -o udp://192.168.2.108:1234

while client port is not available, you see error messages like mmal: Failed to write buffer data (3294 from 14539)- aborting but they do not do any harm.

with nc

I think, this is no longer needed.

pi@raspberrypi:~ $ raspivid -t 0 -n -b 1000000 -g 30 -ih -pf baseline -w 640 -h 480 -fps 30 -o – | nc -p 1904 -u 192.168.2.108 1234

passing video to

pi@raspberrypi:~ $ raspivid -t 10000 -n -b 1000000 -g 30 -ih -pf baseline -w 1920 -h 1080 -fps 30 -o – | gst-launch-1.0 fdsrc ! ‘video/x-h264,profile=baseline, width=1920, height=1080’ ! h264parse ! mp4mux ! filesink location=test.mp4

RTSP streaming

there is a session concept + time stamping (RTP) included. several transport protocols are possible: UDP, TCP and HTTP tunnelled.

RTP/UDP

# raspivid -t 0 -n -b 1000000 -g 30 -ih -pf baseline -w 640 -h 480 -fps 30 -o – | cvlc -v stream:///dev/stdin –sout ‘#rtp{sdp=rtsp://:8554/}’ :demux=h264

$ vlc -v rtsp://192.168.2.104:8554/

further steps

RTSP streaming has many more options like:

• http tunnelling to stream through a firewall
• specifying user and password for stream protection

there are alternative RTSP streaming servers out like:

• live555
• gst-rtsp-server