This library extends the functionality of the one to be found in this repository which is an improvement and extension of this repository. It is meant to work under Python3+ for the Raspberry Pi's GPIO output.
The main addition to its predecessors is the capability to upload image files to an SD card which needs to be poperly formatted (FAT32) and inserted in its slot on the ePaper module. The files must follow the standards defined by Waveshare. Some information about image conversion can be found here.
Example files are part of this repository (test_upload_image.py and test_show_image.py). The upload and write process is not 100 % reliable, it may be that some sleep statements need to be added for processing, YMMV.
IMPORTANT: Power the modules with 5V rather then 3.3V when you intend to write files to the SD card.
The API into this library is very similar to its predecessor and the provided examples there may be easily ported.
For more information about this display, see the waveshare site. There is also a product wiki page.
It requires the GPIO library that is typically available on the Raspberry PI. The example programs require some packages for the QR code rendering and Twisted event loops.
The example programs are centered around displaying Lightning Network BOLT11 invoices in QR Codes that can be picked up by a mobile wallet to perform a payment.
This was developed for a Lightning Network Jukebox demo project. You can see a demo of this here:
Also, the source code for that project is in this repository.
There is a bunch of stuff in the repo, but the featured general-purpose module is in [waveshare/epaper.py]. This module provides the Python 3 API for driving the display for an application.
This diagram is for the Pi 3, and Pi 2. This will probably work on other Raspberry Pi iterations, but double-check that the pinout is the same to be sure. This site has a clearer visual reference for finding the pins.
| PI3 Pin | E-Ink Pin |
|---|---|
| 3.3 v 1* | 6 3.3v |
| GND 6 | 5 GND |
| GPIO15 10 | 4 DOUT |
| GPIO14 8 | 3 DIN |
| GPIO04 7 | 2 WAKE_UP |
| GPIO02 3 | 1 RESET |
*If you intend to upload files it is recommended to power the module with 5 volts (from Pi pin 2) rather than 3.3.
You will need to edit /boot/cmdline.txt and delete the parameter console=serial0,115200 from the line.
Also, you will need to enable the UART interface. Edit /boot/config.txt and add the line enable_uart=1 and reboot.
If you are running with a Raspberry Pi 3, the UART port conflicts with the bluetooth connection and you will need to disable bluetooth for this to work. Edit /boot/config.txt and add dtoverlay=pi3-disable-bt and reboot.
The libpython-dev and RPIO libraries are needed.
sudo apt-get update
sudo apt-get install libpython-dev python3-rpi.gpio
The pyserial package is also needed via pip3
sudo apt-get install python3-pip
pip3 install -U pyserial
For the QR Code examples, qrcode and pillow will need to be installed to render the image to be displayed.
sudo apt-get install libopenjp2-7 libtiff5
pip3 install -U pillow
pip3 install -U qrcode
For the Twisted event loop examples, twisted will need to be installed.
pip3 install -U twisted
test_basic.py This draws some basic text and shapes on the screen in different greyscale colors. Intended as a basic smoke test for the libary and doesn't depend on the QR Code and twisted libraries.
test_qr.py This doesn't draw anything on the e-ink screen, it just tests that the QR code dependency is working properly. It outputs a rendered QR Code as ascii and the coordinate draw instructions on the terminal.
(you can pipe the standard of the script into less like so: ./test_qr.py | less to avoid scrolling by too fast)
test_cycle.py This cycles through several LN Invoice QR Code draws on the e-ink display. It measures the time of the various phases and outputs that on the console for comparison.
test_gpio_input.py This has nothing to do with the e-ink, but just does some basic GPIO push button input. For making sure that works beforecombining htat with the Twisted and e-ink parts.
test_io.py This also has nothing to do with the e-ink, but just does some basic GPIO push button input and LED output for making sure that works before combining that with the Twisted and e-ink parts.
test_twisted_io.py This is an example of using the e-ink display and the GPIO input and output from a Twisted event loop. The example program displayes the QR code corresponding to a push-button input.
test_upload_image.py Transfer an already properly formatted image via serial interface to an SD card.
test_show_image.py Show image stored on the SD card.