The handy stuff

Simply fit the display into the frame and connect it to the Raspberry Pi. That’s pretty much it.
Here is the back view of the frame.

(yes, I used rubber bands to attach the Raspberry Pi to the frame…)

Setting up the Pi

• Get Raspberry Pi OS Lite (Link)
• Follow the installation guide (Link)

Installing R on the Raspberry Pi

Installing R on the Raspberry Pi turned out to be trickier than I thought. I was only able to install version 3.6 from the package sources, but I wanted to have version 4.0.2. I tried following the guides posted here and here but always ran into the problem that the package r-base-core was not available for 4.0.

I ended up compiling R from source, which was surprisingly simple. I loosely followed the guide posted here:

wget https://cran.rstudio.com/src/base/R-4/R-4.0.2.tar.gz
tar zxvf R-4.0.2.tar.gz
# uncomment first line in /etc/apt/source.list
sudo apt-get build-dep r-base 
./configure --prefix=/opt/R/4.0.2 --enable-R-shlib --with-blas --with-lapack

If you run into the error:
configure: error: PCRE2 library and headers are required, or use --with-pcre1 and PCRE >= 8.32 with UTF-8 support
do

sudo apt-get install libpcre2-dev
sudo make
sudo make install

sudo ln -s /opt/R/4.0.2/bin/R /usr/local/bin/R
sudo ln -s /opt/R/4.0.2/bin/Rscript /usr/local/bin/Rscript

and that’s already it. You should now have R ready to run on your Raspberry Pi. Since we are operating on a headless Raspberry Pi, there is no point in trying to install RStudio. I found, however, Nvim R to be an awesome headless substitute (if you are happy using vi, that is).

Setting up the E-Paper display

I simply followed the guide posted on the waveshare wiki.

wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.68.tar.gz
tar zxvf bcm2835-1.68.tar.gz 
cd bcm2835-1.68/
sudo ./configure
sudo make
sudo make check
sudo make install

sudo apt-get install wiringpi

wget https://project-downloads.drogon.net/wiringpi-latest.deb
sudo dpkg -i wiringpi-latest.deb

Communicating with the display from R

The Raspberry Pi can easily communicate with the display via some C or python library. Luckily, both can be integrated in R. I opted for python, due to the amazing R package reticulate which makes the communication between R and python a breeze. I’d be interested, though to package the C library as an R package (eventually).

#python3
sudo apt-get update
sudo apt-get install python3-pip
sudo apt-get install python3-pil
sudo apt-get install python3-numpy
sudo pip3 install Raspberry Pi.GPIO
sudo pip3 install spidev

You’ll also need git to download some additional code.

sudo apt-get install git -y

Then, clone the repository of waveshare that includes the needed libraries.

sudo git clone https://github.com/waveshare/e-Paper

The library we will need is in the folder RaspberryPi&JetsonNano/python/lib.

#!/usr/bin/python
# -*- coding:utf-8 -*-
import sys
import os
import time
libdir="/home/pi/e-Paper/RaspberryPi&JetsonNano/python/lib"
if os.path.exists(libdir):
    sys.path.append(libdir)

from waveshare_epd import epd7in5_V2
from PIL import Image,ImageDraw,ImageFont

try:
    epd = epd7in5_V2.EPD()
    epd.init()
    Himage = Image.open("screen-output.bmp")
    epd.display(epd.getbuffer(Himage))
    epd.sleep()
except KeyboardInterrupt:    
    epd7in5.epdconfig.module_exit()
    exit()

library(reticulate)

use_python("/usr/bin/python3")
py_run_file("display.py")

Build the dashboard in R

Now that we can communicate with the display from python and know how to use python from within R, we can think about what we want to display on the dashboard and how we implement it. Remember, all we have is 800×480 pixels in black and white. Apart from this constrained though, you are free to put whatever you want on the display. I opted for a standard weather, calendar, and date setup, together with some randomly generated pixel art spaceships (my R implementation of a pixel-sprite-generator). The plotting is done entirely with ggplot2.

To reproduce my dashboard setup, simply clone the repository

git clone https://github.com/schochastics/e-Paper-dashboard.git

To use the code, you need to get an API key from openweathermap.org and set up the gcalendr package with your google calendar. The rest should work out of the box (except that it won’t. feel free to ask questions in the comments or on twitter.

Of course you do not have to follow my build. The following code snippet should be sufficient to build your own dashboard from scratch.

library(reticulate)
#load additional libraries, such as e.g. ggplot2
use_python("/usr/bin/python3")

#build your plot object

ggsave("raw-output.bmp",p,width=5,height=3,dpi = 160)
system("convert -colors 2 +dither -type Bilevel -monochrome raw-output.bmp screen-output.bmp")
py_run_file("display.py")

The parameters set in ggsave() makes sure that the output is a 800×480 bmp file and the line thereafter converts the plot to a true black and white image (which speeds up the rendering on the display). For the second line to work you need to install imagemagick.

sudo apt-get install imagemagick

Here is an example dashboard with my code from github.