# RasPi Freezer

![Photo](cad/photo.jpg)

# Usage Instructions
 * Plug HDMI into Beamer
 * Plug USB into Computer
 * booting the Raspberry takes approximately 25 seconds. the green led will light up when ready
 * start freeze.exe from the (newly attached) USB-Drive
 * press button on device or ALT+X or Alt+PRINTSCREEN to take a screenshot
 * simply unplug after use

## Other features
 * you can call freeze.exe with the cmdline argument "single" to just do one screenshot, save it and exit

# Initial setup

## Parts
 * Mini-HDMI <-> HDMI Adapter
 * Mini-USB  <-> USB A Cable
 * Micro-SD-Card >= 2GB
 * Raspberry Pi Zero or Zero W or Model A (Model B/2B/3 not supported!)

## Hardware
           LED     LED SW
     ______||_______|||____
    | :::::::::::::::::::: |
    |                      |
    |_HDMI________USB__PWR_|
       |           |   nc
       v           v
     Beamer        PC

## Build windows snapshot-tool

cd windows-snapshot-tool
mkdir build && cd build
cmake -DCMAKE_TOOLCHAIN_FILE=../Toolchain-cross-mingw32-linux.cmake ../
make


## prepare raspberry pi

install raspbian lite

sudo raspi-config
  * ??
  * ??

sudo su -
apt update
apt dist-upgrade
apt install python3-pyinotify python3-rpi.gpio
apt clean

echo "dtoverlay=dwc2" >> /boot/config.txt

echo "dtoverlay=gpio-poweroff,gpiopin=5,active_low" >> /boot/config.txt

sed -i /boot/config.txt -e "s/^hdmi_force_hotplug=1$/hdmi_force_hotplug=1$/"

echo "libcomposite" >> /etc/modules

apt purge plymouth
systemctl disable getty@tty1

add/change in /boot/cmdline.txt: console=tty3 consoleblank=0 loglevel=3 vt.global_cursor_default=0
(logo.nologo to disable the raspberry)

copy everything to /opt/freezer/
chmod a+x /opt/freezer/display.py
add to /etc/rc.local: cd /tmp && nohup python3 /opt/freezer/display.py 2>&1 &

### read-only root
    wget https://raw.githubusercontent.com/adafruit/Raspberry-Pi-Installer-Scripts/master/read-only-fs.sh
    sudo bash read-only-fs.sh
 * continue: y
 * jumper: n
 * gpio-halt: n
 * watchdog: n
 * continue: y


### this is how to remount read-write later to make changes to the fs
mount -o remount,rw /
mount -o remount,rw /boot


## ToDo
 * korrekte auflösung bei desktop-scaling
 * zu viel overscan
 * hdmi korrekt konfigurieren wenn nach boot erst angeschlossen
 * zeit knopfdruck bis anzeige soweit möglich optimieren