Sketches

E-Ink for Arduino

Table of contents

• Introduction
• Connecting Arduino to the ePaper Board
• Development Tools
• Libraries
• Example Programs
  • Demo Sketch
  • Command Sketch
  • Flash Loader Sketch

Introduction

This project officially supports the Arduino-based platform. The Ti LaunchPad support that is available in the original repaper/gratis repository has been commented out and is completely untested.

The examples have been verified on Arduino Leonardo (R3) and Arduino Uno (R2) boards using the 1.0.5 version of the IDE.

Connecting Arduino to the ePaper Board

See: Schematics for the 2.7 inch E-paper Display Module, Arduino Leonardo (PDF) and Arduino Uno (PDF)

The display module have two 14-pin connectors (J2 is 50mil and J3 is 100mil) and one 26-pin connector (J5). Any one of them can be used to connect the display board to the Arduino board.

One way to connect the display module is to use jumper wires. The table below shows where each wire should be connected:

Arduino Leonardo		Arduino Uno		Arduino Mega 2560		Display, 14-pin connector
Pin #	Signal	Pin #	Signal	Pin #	Signal	Pin #	Signal
GND	GND	GND	GND	GND	GND	1	GND
3V3	3V3	3V3	3V3	3V3	3V3	2	3V3
ICSP-3	SCK	ICSP-3	SCK	52	SCK	3	SCK
ICSP-4	MOSI	ICSP-4	MOSI	51	MOSI	4	MOSI
ICSP-1	MISO	ICSP-1	MISO	50	MISO	5	MISO
8	GPIO	8	GPIO	8	GPIO	6	SSEL
7	GPIO	7	GPIO	7	GPIO	7	Busy
10	GPIO	10	GPIO	10	GPIO	8	Border Ctrl
SCL/3	SCL	SCL/A5	SCL	21	SCL	9	SCL
SDA/2	SDA	SCL/A4	SDA	20	SDA	10	SDA
9	GPIO	9	GPIO	9	GPIO	11	CS Flash
6	GPIO	6	GPIO	6	GPIO	12	Reset
5	GPIO	5	GPIO	5	GPIO	13	Pwr
4	GPIO	4	GPIO	4	GPIO	14	Discharge

The only difference in pinning between the Leonardo and Uno boards is where to connect the I2C/Wire pins (SDA/SCL).

Development Tools

This project officially supports the Arduino-based platform.

The Arduino web site has download links for Windows, Mac OS/X and other operating systems.

Note: Java is necessary to run the GUI, but it is possible to install a command line only version.

Libraries

Link to the libraries source. (copy all of these to you local libraries folder)

• Images - Sample XBM files. The demo program includes two of these directly. The Command program can use these files for its upload command.
• FLASH - Driver for the SPI FLASH chip on the EPD eval board.
• EPD2 - E-Ink Panel driver (COG V2) experimental.
• LM75 - Temperature sensor driver.

Example Programs

IMPORTANT NOTES for COG V2

1. The programs below only support the COG V2 using the EPD2 library.
2. The COG V2 does not use PWM - the pin is used as chip select for the onboard SPI-NOR flash instead.

Demo Sketch

Link to the demo2 source.

This example first clears the screen, then toggles between two images. It needs the serial port (9600 8N1) connected and displays the version, temperature and compensation values on each cycle.

This is built upon the EPD2 API in the libraries folder and shows how to use the API to display images from the MCU FLASH. Only a few images are possible to be stored since the on-chip FLASH is limited.

Command Sketch

Link to the command2 source.

A command-line example that accepts single character command from the serial port (9600 8N1). Functions include XBM upload to the SPI FLASH chip on the display board, display image from this FLASH and several other functions.

Use the h command on the serial port (9600 8N1) to obtain a list of commands. Some of the commands are shown like e<ss> this represents a two digit FLASH sector number in the range 00..ff (a total of 256 sectors). The 1.44" and 2.0" display images take one sector but the 2.7" displays take two adjacent sectors - this means that it is necessary to issue both e00 and e01 before uploading a 2.7" image with u00.

When using the serial monitor on Arduino/Energia IDE any command that take a hex number as parameter needs a <space> character after it, as the Send button will not automatically add a CR/LF. For single letter commands like the t temperature sensor read just type the character and click Send.

The 4 stage display cycle is split into two separate commands. The r command removes an image and the i command displays an image. e.g. if the current image was from sector 30 and you wanted to change to sector 43 then type r30<space>i43<space> into the serial monitor and click Send.

The upload command u need a terminal emulator with ASCII upload capability or the ability to respond to a paste of the entire contents of an XBM file. Also note that the u command does not erase the sector before uploading. To use the upload to upload an XBM into sector 3b for example type u3b<space> then start the ASCII upload or paste the contents of the XBM file into the terminal window on upload completion an image size message is displayed.

The image stored is compatible with the flash_loader sketch as described below and that program can be used to cycle through a set of images uploaded by this program.

Typical use: h to bring up the help, t to check that the temperature is working and then w to clear the display. To upload an image do e00, e01 and then u00. Send the image file from the terminal program and then type i00 to display it.

Flash Loader Sketch

Link to the flash loader source.

This program has two modes of operation:

1. Copy a #included image to the FLASH chip on the eval board. define the image name and the destination sector. After programming the image will be displayed

2. Display a sequence of images from the FLASH chip on the eval board. A list of sector numbers an millisecod delay times defined by the DISPLAY_LIST macro to enable this mode. In this mode the flash programming does not occur. The images are stored in the same format as the command program above, so any images uploaded by it can be displayed by this program

The configuration of both modes is handled in this block of code:

// select image from:  text_image cat ea aphrodite venus saturn
// select a suitable sector, (size 270 will take two sectors)
#define IMAGE         ea
#define FLASH_SECTOR  0

// if the display list is defined it will take priority over the flashing
// (and FLASH code is disbled)
// define a list of {sector, milliseconds}
//#define DISPLAY_LIST {0, 3000}, {2, 3000}, {4, 3000}

Note: To show three different images with the DISPLAY_LIST as shown above you will have to upload the program four times to the Arduino:

1. DISPLAY_LIST not defined, IMAGE is e.g. ea, FLASH_SECTOR is 0
2. DISPLAY_LIST not defined, IMAGE is e.g. cat, FLASH_SECTOR is 2
3. DISPLAY_LIST not defined, IMAGE is e.g. venus, FLASH_SECTOR is 4
4. DISPLAY_LIST defined and set to {0, 3000}, {2, 3000}, {4, 3000}