Table of contents
- Prerequisites
- Preparations
- Connecting Raspberry Pi to the ePaper board
- Standalone EPD Test Program
- EPD Driver
- Python Examples
The code in this repository is ONLY VALID on ePaper modules that are rev D and have the EM027BS013 display mounted. To see what your module has, look at the back of it:
The board in the image above is rev D (as shown in one of the circles) and it is a EM027BS013 display, shown by an X next to the name. If the board is rev D but the two checkboxes for EM027AS12/EM027BS13 are missing, then it is assumed that it is a EM027BS13 display.
If your board is not rev D or if it is a rev D board with an EM027AS12 mounted, then go to the product page and look under EM027AS012 in the table.
The new Raspberry Pi 2 (and possibly the A+ and B+ models as well) come with the option to enable and disable SPI communication. It is off by default. To enable it run the following command:
sudo raspi-config
In the dialog that appears, navigate to Advanced Options and then SPI. Select to enable it. The question about loading driver at startup does not matter. Reboot.
The A+, B+ and version 2 models come with 40 gpio pins. You can use a 40-pin ribbon cable and connect part of it like this:
Note that the keying must be as shown in the images for the pins to align correctly. As the cable is 40 pins and the pin list is 26, 14 pins will stick out. Make sure they stick out on the side as shown above.
The A and B models come with 26 gpio pins. You can use a 26-pin ribbon cable and connect it like this:
Note that the keying must be as shown in the images for the pins to align correctly.
This will first clear the panel then display a series of images (all 2.7" images from Arduino example). This need the Linux SPI module installed.
Start by loading the SPI module. Old installations of Raspbian Wheezy use
the spi-bcm2708 module, while newer installations of Raspbian Wheezy and
Raspbian Jessie use spi-bcm2835. Load the version that you need:
sudo modprobe spi-bcm2708
Build and run using:
COG_VERSION=V2 make rpi-epd_test
sudo ./driver-common/epd_test 2.7
The EPD driver needs the fuse development library installed.
# Raspberry Pi
sudo apt-get install libfuse-dev
The EPD driver allows the display to be represented as a virtual director of files, which are:
File Read/Write Description
-------- ----------- ---------------------------------
version Read Only The driver version number
panel Read Only String describing the panel and giving its pixel width and height
current Read Only Binary image that matches the currently displayed image (big endian)
display Read Write Image being assembled for next display (big endian)
temperature Read Write Set this to the current temperature in Celsius
command Write Only Execute display operation
BE Directory Big endian version of current and display
LE Directory Little endian version of current and display
Command Byte Description
-------- ----- --------------------------------
'C' 0x43 Clear the EPD, set `current` to all zeros, `display` is not affected
'U' 0x5A Erase `current` from EPD, output `display` to EPD, copy display to `current`
Notes:
- The default bit ordering for the display is big endian i.e. the top left pixel is the value 0x80 in the first byte.
- The
BEdirectory is the same as the rootcurrentanddisplay. - The
LEdirectorycurrentanddisplayreference the top left pixel as 0x01 in the first byte. - The
current_inverseanddisplay_inverserepresent black as zero (0) and white as one (1) while those item without the suffix represent the display's natural coding (0=>white, 1=>black) - The particular combination of
BE/display_inverseis used in the Python EPD demo since it fits better with the Imaging library used.
Start by loading the SPI module. Old installations of Raspbian Wheezy use
the spi-bcm2708 module, while newer installations of Raspbian Wheezy and
Raspbian Jessie use spi-bcm2835. Load the version that you need:
sudo modprobe spi-bcm2708
Build and run using:
COG_VERSION=V2 make rpi-epd_fuse
sudo mkdir /tmp/epd
sudo ./driver-common/epd_fuse --panel=2.7 -o allow_other -o default_permissions /tmp/epd
Verify that it worked by checking version and panel type, should return 3 and EPD 2.7 264x176 COG 2
cat /tmp/epd/version
cat /tmp/epd/panel
Clear screen:
echo C > /tmp/epd/command
Send image to display and update display to show it:
./driver-common/xbm2bin < ./driver-common/cat_2_7.xbm > /tmp/epd/display
echo U > /tmp/epd/command
To shut down:
sudo umount -f /tmp/epd
sudo rmdir /tmp/epd
To have the EPD driver loaded automatically after a reboot, a startup script
must be installed in in /etc/init.d and the driver must be installed in /usr/sbin.
There is a make target that does this.
sudo COG_VERSION=V2 make rpi-install
sudo service epd-fuse start
The service places the files under /dev/epd/ instead of /tmp/epd/ so to see the files:
ls -l /dev/epd
To stop the service temporarily:
sudo service epd-fuse stop
To start the service again:
sudo service epd-fuse start
To permanently preventing EPD driver to start at boot (note that this command
must be executed when the service is running, i.e. you should not do a sudo service epd-fuse stop
first):
sudo COG_VERSION=V2 make rpi-remove
These need the PIL library installed:
# Raspberry Pi
sudo apt-get install python-imaging
The examples also need the Starting EPD Driver at Boot
Draw some lines, graphics and text
python demo/DrawDemo.py
- Accepts a lists of image files on the command line.
- Converts them to grey scale to ensure formats like PNG, JPEG and GIF will work.
- Inverts the image since the E-Ink panel is reverse (i.e. black on white).
- Converts image to single bit (PIL "1" mode).
- Display the middle of the image (using crop function).
- Delay.
- Display the re-sized image.
- Delay before fetching next file.
Note if scratch is installed on the system, the following commands will show some cartoon animals. The images when re-sized will be distorted if the aspect ration of the original image is not the same as the display.
python demo/ImageDemo.py /usr/share/scratch/Media/Costumes/Animals/cat*
python demo/ImageDemo.py /usr/share/scratch/Media/Costumes/Animals/d*.png
This demo works in the same way as the other Image demo but instead of always waiting 3 seconds between each update it is now possible to advance to the new image using the button on the display board.
Note that to access the GPIO library needed for the button the program must be executed with root privileges:
sudo python demo/ImageDemoButton.py /usr/share/scratch/Media/Costumes/Animals/cat*
sudo python demo/ImageDemoButton.py /usr/share/scratch/Media/Costumes/Animals/d*.png
Display random overlapping rectangles using partial update. First argument is number of rectangle to generate before updating the EPD, second number is the number of frames to display before the program exits.
python demo/PartialDemo.py 3 20
Display a 4 digit hex counter uses partial update to only change the updated digits.
Use Ctrl-C to stop this program.
python demo/CounterDemo.py 3 20
Displays the current time (in minutes), date and weekday. Updates every minute to show the current time.
Use Ctrl-C to stop this program.
python demo/Clock27.py
Displays the current time (in secodns) and date. Updates every five seconds to show the current time. Note that this demo will almost continuously update the display so it will be a constant flicker.
Use Ctrl-C to stop this program.
python demo/ClockDemo.py
Displays the current IP address and gateway. If the network connection is lost the display will instead show a Not Connected message until the connection is restored again.
Use Ctrl-C to stop this program.
python demo/IpAddrDemo.py
Generates and displays two bar codes. See more information in the ./demo/barcode/ subfolder.
This program must be executed from inside the ./demo/barcode/ folder and with a special command:
PYTHONPATH=.. python BarCodeDemo.py