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Fast Update notes, July 2017

The update rate for Partial Update is determined by the temperature dependent stage time. For 25 degrees C a typical max update rate for the 2.7" display is about 1.5 Hz.

The stage time decreases as the measured temperature increases. For some applications a faster update rate can be useful. This can be achieved by setting the stage time directly bypassing the normal temperature dependent setting of the stage time. This is the same mechanism as used in the Pervasive Displays Windows application for the TI Launchpad and the EXT2 development board (http://www.pervasivedisplays.com/kits/ext2_kit).

Decreasing the stage time increases the max update rate. If the stage time gets too small some ghosting (left overs from the previous image) will occur. Depending on the application some ghosting may be acceptable.

This implementation uses the 'F' command to do a Fast Update using the stage time as set in /dev/epd/f_stage_time.

A video demonstrating the normal Partial Update and Fast Update for various stage times is available on YouTube.

Partial Update notes, February 2016

This partial update implementation follows the algorithm outlined in the discussion of issue #19 on the repaper/gratis github repository.

The original code in epd_fuse.c and V231G2/epd.c under PlatformWithOS did a full 4 cycle display update including COG power on and COG power down sequence. This resulted in the update taking more than 3 seconds with the display first showing the updated image, then the original image followed finally by the updated image. This made things like a clock, counters and 'game of life' look very bad.

Following changes as outlined in issue #13:

in epd_fuse.c run_command() do not call EPD_end() at the end of the 'P' command (only if partial update is supported by the display)
in epd.c introduce COG_on status variable in EPD_struct.
in epd.c EPD_begin() return immediately when COG_on is true
in epd.c EPD_begin() set COG_on to true at the end of the function.
in epd.c EPD_end() set COG_on to false at the end of the function.
in epd.c EPD_partial_image() only call the last stage (EPD_normal).

With these changes you can get a proper partial display update frequency < 1 Hz.

For a YouTube video showing the difference between before and after the fix see https://youtu.be/dciaFRKtetU

Notes for Energia support, August 2015

Updated 2015-08-01 by Rei Vilo

Added #include Energia.h
For Energia, changed pin names to pin numbers (pin names are deprecated)
Works on MSP430F5529, LM4F120, TM4C123
Fails on MSP432 and CC3200
Recognize the FPL material type by the rear labels
Use branch rei-vilo / gratis / CC3200 and MSP432
The master supports MSP432 but not with direct connection as Energia startup code allocates one pin as not GPIO

Sketches

These are example programs that will compile and run on the following platforms

TI LaunchPad with M430G2553 using the Energia IDE
Arduino Leonardo using the Arduino IDE

Notes for Arduinos with the embedded USB controller

Arduinos with the embedded USB controller ('Un' suffix) do not have a real serial port, it is emulated using firmware and uses the USB interface.
Arduino Loenardo uses one of these chips.
The Command program needs the serial to accept commands so it will wait indefinitely for the serial monitor to be opened before doing any display. (the additional delay code is commented out)
The Demo, Flash Loader and Thermo programs do no need serial port to accept commands, it is display only. The additional delay is used and the indefinite wait is commented out. Therefore on a Leonardo to see the initial messages open the serial monitor before uploading. If the serial monitor is not open these programs will now automatically start.

PlatformWithOS

Contains an example driver and Python demo programs that can be compiled and run on: