# HG changeset patch # User Paul Boddie # Date 1369694515 0 # Node ID a4f6bb77805c7a4c899d5e1582d8f82b0bfa2fa5 # Parent 0ee6f445296c070551b7c4bed7dc3189a691fc26 Added some documentation. diff -r 0ee6f445296c -r a4f6bb77805c README.txt --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/README.txt Mon May 27 22:41:55 2013 +0000 @@ -0,0 +1,183 @@ +Introduction +------------ + +The ben-epaper distribution provides a program, epaper, that runs on the Ben +NanoNote and controls the EM027AS012 display from Pervasive Displays on an +Embedded Artists' 2.7 inch E-paper Display module. To connect the module to +the Ben, the 8:10 port which is typically employed to access microSD cards is +instead used to hold a suitable breakout board that exposes the 8:10 port's +connectors to other circuits. These connectors are in turn connected to +specific connectors on the E-Paper Display module as follows: + +Sniffer UBB EM027AS012 +------- ---- ----------- +DAT2 DAT2 4 (MOSI) +CD DAT3 6 (SSEL) +CMD CMD 11 (PWM) +VCC VDD 13 (PANEL) +CLK CLK 3 (SCK) +GND GND +DAT0 DAT0 12 (RESET) +DAT1 DAT1 14 (DIS) + +On the E-Paper Display module the socket appears as follows, with the numbered +pins protruding from the board: + + Socket +-------------------- + 2 4 6 8 10 12 14 + 1 3 5 7 9 11 13 +---------__--------- + +However, it is more convenient to use standard male-to-male jumper wires to +connect the Sniffer or UBB breakout board to the end of a suitable cable which +in turn plugs into the socket on the E-Paper Display module board. The jumper +wires plug into the holes in the cable plug. Remember that the pin numbering +is "mirrored" on the end of the cable: + + __ +--------- --------- + 1 3 5 7 9 11 13 + 2 4 6 8 10 12 14 +-------------------- + Cable + +In addition to the Sniffer or UBB connections, additional connections for 3.3V +power and ground must be connected as follows: + +3.3V Supply EM027AS012 +----------- ---------- +GND 1 (GND) +3V3 2 (3V3) + +Note that the VCC output of the 8:10 port is used as a "power control" signal +and not to power the display board. + +Collecting Images for Display +----------------------------- + +Before building the epaper program, you will first need to collect some images +with the following specific properties: + +Width: 264 pixels +Height: 176 pixels + +An image preparation program then needs to be run on a list of image filenames +to produce suitable source files incorporated into the built program. This is +done as follows: + +python tools/bitmap.py images file1.png file2.png file3.png + +Here, three PNG files are loaded, internally converted (the files are not +changed), and the bitmap data written out to two files: + +images.c +images.h + +Since the Makefile and epaper program references these files, it is +recommended that the "images" basename be retained when running the bitmap.py +program. + +Building the Software +--------------------- + +Before building the software, it will probably be necessary to edit the +Makefile to specify the locations of the cross-compilation toolchain and of +libubb. Obtaining a toolchain and libubb is currently beyond the scope of this +document. + +The epaper program is built as follows: + +make + +Running the Software +-------------------- + +On the Ben, the epaper program can be deployed together with libubb in a +particular directory and invoked as follows: + +LD_LIBRARY_PATH=. ./epaper + +Alternatively, the library search path can be configured properly and the +epaper program installed in such a way that merely typing the name of the +program is enough to run it. + +The epaper program accepts a list of options: + + This indicates which image to display (where 0 is + the first image). + +--have This indicates that the display is showing the + image with the given number (where 0 is the first + image) and is used to influence subsequent + options. + +--blank This blanks the screen, using knowledge of the + current screen image if provided either by the + --have option or by the display of a preceding + image. + +--wait This causes a delay between operations. + +Hardware: Embedded Artists' 2.7 Inch E-paper Display Module +----------------------------------------------------------- + +This board provides an interface to the EM027AS012 display from Pervasive +Displays: + +http://www.embeddedartists.com/products/displays/lcd_27_epaper.php + +This software has only been tested with revision A of the board, and employs +code from Pervasive Displays that may have been superseded upon release of new +revisions of this and related boards (as mentioned below). + +More information and source code licensed under Free Software licences can be +found on the RePaper site: + +http://repaper.org/ + +Other boards that provide an interface to the EM027AS012 display and other +displays from the same manufacturer also exist. For example: + +http://www.adafruit.com/products/1316 + +This software has not been tested with such boards. + +Hardware: 8:10 Port Breakout Board +---------------------------------- + +To connect the Ben NanoNote to the E-Paper Display module, a suitable breakout +board is required to expose the connections inside the 8:10 slot. To achieve +this, the Sparkfun microSD Sniffer has been used: + +https://www.sparkfun.com/products/9419 + +This board is apparently intended for eavesdropping on communications between +a "host" device with a microSD slot and a microSD-based device that can be +inserted into a slot mounted on the board (instead of being inserted directly +into the host device). However, the board-mounted slot can be ignored and the +exposed connections routed to the display board instead. + +Another board that achieves the same purpose is the Universal Breakout Board +(UBB): + +http://en.qi-hardware.com/wiki/UBB + +The UBB is somewhat more difficult to work with as its connectors are very +small and, compared to the microSD Sniffer, awkward to attach things to. The +microSD Sniffer employs connectors situated around holes with 0.1 inch +spacing, meaning that commonly available connection headers can be soldered +onto the board. + +Although the labelling of the connections is different between the microSD +Sniffer and UBB (see above), the layout appears to be identical. + +Contact, Copyright and Licence Information +------------------------------------------ + +The author can be contacted at the following e-mail address: + +paul@boddie.org.uk + +Copyright and licence information can be found in the docs directory - see +docs/COPYING.txt and docs/gpl-3.0.txt for more information.