Quietpaper - Smart Home Display Project

This is a passion project that realizes an Raspberry-Pi-based smart home display using the 3-color Waveshare e-Paper Display 7.5 inch. I wanted to make a device my smart home control station that does not emit blueish light, that is quiet and does not listen or talk (unlike Alexa, Google & co.) and generally provides a zen-like user experience and still integrates well with various APIs. Here now the code is, ready to be used and extended by you!

The application structure is modular and supports multiple widgets (as information windows) and displays (as information projection screen) so integration into other media is feasible (for example, currently the image is not only shown on the e-paper display but also saved as PNG and uploaded to Google-Docs for remote-display).

The application is developed as Python application that can be run as a linux daemon and update the system at regular times (currently multiples of 5 minute steps which I found best for the slow refresh cycles of the Waveshare display).

The application also talks to a concurrently running NodeJs application (called hafasglue) in order to interface with the German "Deutsche Bahn" public transit API "Hafas". You can forego this concurrently running application and configure the corresponding widget to retrieve data from the Google Directions API instead - which is unfortunately not for free but (given that API calls are not cached) rather pricey.

Here are some other libraries and projects that were helpful and/or whose code I ended up incorporating into this project:

• rgerganov/py-air-control - Command Line App for controlling Philipps Air Purifier - modified version stored at quietpaper/iot/airctrl.py
• public-transport/hafas-client - Hafas is the German "Deutsche Bahn" system that provides the electronic public transit timetables and this is a NodeJs client of of their rather clunky XML Webservice. The client is supplied as a much leaner REST-API by my NodeJs servlet in hafasglue.
• momorientes/istheutefeinstaubalarm - my town Stuttgart, Germany provides "Smog Alerts" on which days we should leave our cars at home, use public transit for lower price (in some cases even for free) and cannot use "recreational home fireplaces". This project provided the inspiration on how to query if such a smog alert is currently in effect: by scraping the city's minimalistic mobile-phone widget HTML page.
• albertogeniola/MerossIot - library to access power consumption data of the Meross Smart Home Power Plugs
• Tado API Guide - updated for 2019 - huge help in understanding how to query the undocumented API of my tado thermostats.
• Tutorial on Programming a Waveshare 7.5-Inch Multi-Color e-Paper Display & Info-Frame - very great tutorial to get started with the Waveshare. I took the Weather-Display logic directly from that tutorial.

Install / Run

1. You need the following prequisites:

• Raspbian Stretch Image
• Python 3 Installation
• Node Version Manager or Node Package Manager
• Display connected to Raspberry

2. Next, if you want to use all widgets exactly in the layout I use you can just copy the folder secret.template, rename it to secret and open the config files within replacing all access keys, passwords and personal data with values that apply to your situation.

3. If you would like another configuration, you might want to develop own widgets or re-arrange them. For this, see the next chapters. You might at least want to edit the file quietpaper/config.py which sets the layout of the widgets on the display.

4. You can then install both the quietpaper daemon (Python app which updates the display) and the hafasglue daemon (Node-JS servlet which talks to Hafas in order to retrieve public transit information) by calling:

./install-and-autorun.bash

5. The display will now load! - You can start/stop/restart the daemons by calling

sudo service {start|stop|restart} {quietpaper|hafasglue}

... or, after stopping the services, run them directly with:

./hafasglue.bash
./quietpaper.bash

Widgets

The core of this project are its "widgets", the different information snippets displayed. The following widgets are developed (and stored in the subfolder quietpaper/widgets):

Python file	Icons	Description
allergy.py		air quality as reported by Philipps Air Purifier and (potentially some time in the future) also the air quality reported outdoors on "some" public website
cal.py		the next appointment on some Google calendar
clock.py	-	time and date (during night/workday, the time is hidden because the display uses a longer update cycle)
commute.py	, ,	upcoming routes from your home into the city assuming a "bus -> train -> city" route (as it is the case in my current home); can also show additional information such as bus/train leaving from another station (small character suffix) or delays in the bus/train timetable (small +... suffix)
monitor.py	, ,	small symbols indicating if some of your electronic devices are running or down (Network Attached Storage, VPN, internet connection)
office.py	,	showing ONLY the time of your first appointment at work in the morning (for work-life-balance-purposes hiding the title etc. in order not to break you out of your home-sweet-home feel); uses either a Google Docs Sheet (which you can fill by other means) or a Google Calendar as source for this information; also can add an asterisk if the appointment is marked as "special"
room.py	, , , , , ,	room climate information from tado thermostats including temperature, warm-up/cool-down indicator (, , window-open indicator and humidity as well as humidity "alarm"; window-open indicator supports three states: window closed (), window open (), "window was already opened to let fresh air in today" (no icon)
separator.py	-	a straight horizontal line
smog.py		indicates whether the city of Stuttgart currently has a smog alert or not
trashday.py	, , ,	displays whether it is a day where we should put out the garbage to be picked up (for different kinds of garbage: bio , paper , recycle , waste )
wheather.py	icons based on font font/meteocons-webfont.ttf	weather information from https://api.openweathermap.org
laundry.py	, , ,	Indicator whether the washing machine and dryer (in our basement) is running or done. Computes this by using power usage metrics from smart home plugs from meross.

Develop

If you want to modify this project and/or adapt it to your need, here are some pointers about the repo's directory structure:

• data - contains static data displayed by some widgets, e.g. the dates used by the trashday.py widget
• doc - contains artifacts for this document
• fonts - fonts used on the display
• hafasglue - logic for the hafasglue NodeJs servlet
• icons - bmps and gifs of the icons displayed on screen (only bmps are actually used in the code)
• log - directory where log is stored
• output - directory where png images are stored for debug purposes
• quietpaper - the main python application (python module) with the following submodules
  • iot - logic to interface with devices (e-paper display, air purifier, tado thermostat)
  • screens - classes that provide interfaces for displaying the final image
  • widgets - classes that retrieve information from other sources and render it onto the screen
• secret.template - template of config files that contain all necessary access keys, passwords and personal information. Before launching the application copy this directory to secret and replace all placeholders

For development on Raspberry Pi, I recommend Visual Studio Code with Remote Development Extension as well as NoMachine to login to the Raspberry. Happy Developing!

Speeding Up the Refresh Rate

At the time of this writing this application is running for about a month and the display is holding up very well! The only caveat is the slow refresh rate of the display (about 30 seconds) which limits the acceptable display refresh rate to once every five minutes.

Applied Science on Youtube has produced an excellent video "E-paper hacking: fastest possible refresh rate" but unfortunately the technologies used seem not available for the 7.5 inch display. The code in the respective places is left out, there are some vague hints at respective byte sequences in the spec sheet but corresponding reference VCOM LUT tables are documented nowhere.

Asking both at the very friendly support of Waveshare and at Good Display they essentially discouraged me from experimenting with the LUT table even hinting at that it might not be possible. As you can see they have a successor in their portfolio though. If anyone has experience with it or reverse engineers the LUT and finds a quicker setting that does not fry the display, let me know at post at benkku dot com!