This project implements a small infoscreen using a Pi and a 7"-touchscreen. For efficiency reasons, the screen should only run while somebody is at home, so the system automatically boots when it detects motion and automatically shutsdown when nothing moves anymore.
Once booted, the system cycles through a list of predefined webpages.
The hardware consists of
- a microcontroller (PIC12F675, but almost any microcontroller will do)
- an IR motion sensor (HC-SR501, cheap and widely available)
- a Pi3
- a Waveshare 7"-touchscreen
- a circuit with a P-channel mosfet
For details about the PIC and the circuit, browse the hardware-directory.
Note that it is possible to run the infoscreen without the added luxury of a PIC and/or an IR motion sensor. In case you don't have a PIC you have to manually start the system (or let it run all the time). Since using the sensor does not require soldering, you could use the sensor together with the Pi to at least automatically shutdown your system.
The system starts in state "Z1": the Pi is shutdown and the PIC controls the motion sensor (PIR). Motion will trigger a high-level on the out-pin of the PIR, which is attached to the PIC. Now the PIC will set the gate of the mosfet to low, thus turning on current for the Pi.
Now we are in state "Z2": the Pi is up and running and in charge of any interrupts from the PIR. In this state the PIC is sleeping. Everytime the Pi detects motion he will postpone his shutdown for a given time (e.g. 15 minutes). If there is no motion for 15 minutes, the Pi will shutdown and pull Pin4 high. This is the signal for the PIC that we are back to state "Z1" and to take over again.
The circuit shows the wiring of the project. The PIR-out is connected to the GP2 of the PIC as well as GPIO17 of the Pi. In addition, GPIO4 of the Pi is connected to GP4 of the PIC - the Pi uses this connection to signal shutdown to the PIC.
Note that this version
also uses a step-down converter from 12V to 5V to supply a stable voltage to the system.
You should start out with a fresh install of Raspbian-Pixel desktop (tested with Stretch, other versions might or might not work). Then run
git clone https://github.com/bablokb/pi-infoscreen.git
cd pi-infoscreen
sudo tools/install
cd ..
git clone https://github.com/bablokb/gpio-poll-service.git
cd gpio-poll-service
sudo tools/install
The second install command will ask you to edit /etc/gpio-poll.conf, but
this is not necessary since the first install provides a suitable configuration.
Note that the installation of the pi-infoscren project will alter your
/boot/config.txt. It configures HDMI for the 7"-touchscreen from Waveshare.
If you don't us this display then you must edit the file before rebooting
your system!
The installation also modifies the autostart-behavior of the system. During boot, it will automatically load chromium in kiosk-mode and show a local web-page in app-mode which in turns cycles through a list of configured web-pages.
You can modify the autostart-behavior in
/home/pi/.config/lxsession/LXDE-pi/autostart and the list of web-pages in
/usr/local/lib/iscreen/web/js/config.js.
To make better use of the screen-space it is advisable to install a so called "user-agent-switcher" within chromium from the chrome-webstore. Using the switcher chromium can prentend to be running on a small device (e.g. an iPhone6) and some (but not all) webpages will deliver pages more suitable for small screens.