Joshua Kettlewell | Projects

Joshua Kettlewell

Ph.D Student,
Singapore University
of Technology and Design

Making an E-ink display

So I was inspired to build a eink twitter feed as preparation to making an eink display for the next prototype of the cryptclip. I saw this thread on reddit here which covers everything quite well. And here is another article that gives the step by step instructions. I've trascribed them below to make it easier for other people doing this, and for me to remember how I got it working.

homomorphic

What?

The aim was to get the eink screen connected to raspberry pi. The pi is in turn connected to the internet and uses the tweepy python library to pull down data from twitter which is then displayed on the eink screen. This is nice as the eink doesnt draw power when displaying, only when changing, so it has a long battery life.
The purpose of getting to know the e-ink screen is to use it within a different project, wherein is comunicates with a phone and completes a secure cryptographic protocol. If you think its really cool the Whatsapp is secure with end to end encryption then youll love what we have planned.

Running the demo

Running images from my group webpage.

Step 1: Buying the componets.

The easy bit. Items used are as follows:

  • Raspberry Pi Model 2B+ running the WheezyPi operating system. I got mine from SGBotics here.
  • The screen a ribbon cable. The screen I bought from embedded artists. Embedded artists seem to make alot of cool e-ink an pi related products so I hope to try out some other tech from there in the future. Also - eveything is fantastically documented. The eink screen is documented here. The final piece is simply a ribbon cable to connect the pi to the screen via the GPIO pins. I had one knocking around but if you dont have one you can get them at any electronics shop, or online store. They should be available anywhere you can buy a Pi.

Step 2: Terminal commands

So after plugging it al together then the process is actually very simple. All we need to do is install everything onto the pi and essentially tell tweepy when to be scrapping off twitter. So - lets get right in there with the terminal commands:

Clone the git repository

  • git clone https://github.com/mbeddedartists/gratis.git

Confirm that the module is setup

  • sudo modprobe spi-bcm2708

Install dependicies

  • sudo apt-get install libfuse-dev
  • sudo apt-get install python-imaging

Build everything

  • /home/pi/gratis/PlatformWithOS
  • COG_VERSION=V2 make rpi-epd_fuse
  • sudo modprobe spi-bcm2708
  • sudo ./driver-common/epd_fuse --panel=2.7 -o alolow_other -o
  • sudo mkdir /tmp/epd
  • sudo COG_VERSION=V2 make rpi-install
  • sudo service epd-fuse start ls -l /dev/epd

Now test the configuration

  • cat /tmp/epd/version
  • cat /tmp/epd/panel
  • COG_VERSION=V2 make rpi-epd_test
At this point you should set up a twitter account (if you dont already have one) Change the account stuff here once logged in.

Now rename some stuff

  • mv tweepy_auth.py-SAMPLE tweepy_auth.py
  • tweepy_auth.py-SAMPLE
  • Modify the demo file called tweepy_auth.py
  • basic = False CONSUMER_KEY='' CONSUMER_SECRET ='' ACCESS_TOKEN='' ACCESS_TOKEN_SECRET=''
  • pip install tweepy

And thats it!

If you were folling this guide you should now have a working twitter eink feed! You can test it by running the demo file which should be in /home/pi/gratis/PlatformWithOS