By Jonathan Gutow (version 1.2, December 9, 2020)
For less than US$400 you can build a quite capable tablet that
works well as a projected whiteboard and is capable of producing
nice screen casts of what you write. Additionally, it has
capabilities that many more expensive tablets do not:
|Raspberry Pi 4B (2 or 4 GB, 3B+ will work, but may have issues recording)||35 (2GB)
|Power supply for Pi
||12 - 14*
|128 GB microSD card (be careful not all
brands work with Pis)
||16 (Samsung Evo Select U3)*
|Artist's Display (Reasonable priced options
from XP-Pen and Huion.)
||200 (XP-Pen 12Pro)
255 (XP-Pen 13.3Pro)*
250 (Huion Kamvas Pro12)
280 (Huion Kamvas Pro13)
|2 6 - 8" microHDMI to HDMI cables (second
output to projector)
|USB Headset (if recording audio for screen
||33 (Mairdi, Bigger Earmuff-Binaural)|
|Case for Pi
||? (Built my own. Plastic cases ~10)
|OS (Rasbian or Lubuntu*, see below)
|"whiteboard" (Xournal++, see below)
|Screen overlay annotator (Gromit-MPX, see
|Screen cast recording software (Vokoscreen,
Total monetary outlay (no USB Headset)
| 275 - 350
* Recommended (equivalent of what I am using).
The easiest way to do this is buy a simple plastic case for the
Pi. This will leave you with a minimum of three cables to deal
with: power supply, cable to artists display, cable to projector
system. If you want a more elegant tablet and portable tablet see
my notes on building a case and powering it with a USB power bank.
Rasbian (easiest install)
#Overscan messes up most modern LCD/LED displays. Disable
#It would be nice if monitors powered down when the Pi 4
sleeps the screen, but it is not implemented yet.
# However, this command will make it work once it is implemented.
#Enable both hdmi outputs even if a screen is not plugged
in. This will run your Pi a bit hotter and use more power.
hdmi_group:0=2#Only the Pi 4 has two hdmi ports
#The following may need to be adjusted depending on the projectors available see the video settings at raspberrypi.org.
# This is appropriate for a maximum resolution of 1680X1050 on the second monitor.
- Put the microSD card into the Pi. Hook up mouse, keyboard and monitor (artists display) to hdmi port 0.
- Boot up the Pi and create your user administrator account.
- Connect to hardware ethernet. This is a big install. You do not want any dropping out in the middle.
- Install the desktop.
sudo apt update sudo apt install lubuntu-desktop
- When the install is complete you can reboot:
sudo reboot now
- On reboot you should get a graphical login.
sudo apt update
sudo apt install xournalpp
sudo apt install gromit-mpx"
sudo apt install vokoscreen".
- Whiteboard (Xournal++): I set up a template with 6 blank pages in it for a one hour lecture. The template should also be set up so that it sized appropriately to show up on the projected screen. I then open the template and save a copy named for the date and class. When screen casting, I only record part of the screen, leaving space for the recording software controls. If I have slides to show I usually convert them to .png files and load them into the template before class as images. Then I can write on them, move, enlarge or shrink them during class.
- Vokoscreen: This requires some fiddling. Exactly which input will give you audio depends on your specific microphone system. You also need to play with the microphone placement to avoid breathing noises and other unwanted noise.