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GxEPD2 variant with support for 4 grey levels on supported e-papers
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With full Graphics and Text support using Adafruit_GFX
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For SPI e-paper displays from Dalian Good Display
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and SPI e-paper boards from Waveshare
- 4 grey levels are available on some e-papers that support differential refresh
- 4 grey level support can be used instead of differential refresh
- "old data" and "new data" controller buffers provides 2 bits per pixel
- the 4 states per pixel can produce 4 grey levels using a special waveform
- the 4 grey level waveform table is taken from demo from Good Display
- the 4 grey levels may differ from display to display, and may be temperature dependent
- ghosting can't be avoided; using clearScreen() helps
- the display panels are for 3.3V supply and 3.3V data lines
- never connect data lines directly to 5V Arduino data pins, use e.g. 4k7/10k resistor divider
- series resistor only is not enough for reliable operation (back-feed effect through protection diodes)
- 4k7/10k resistor divider may not work with flat cable extensions or Waveshare 4.2 board, use level converter then
- do not forget to connect GND
- the actual Waveshare display boards now have level converters and series regulator, safe for 5V
- use 3k3 pull-down on SS for ESP8266 for boards with level converters
- note that 7.5" e-paper displays don't work reliable if fed from 3.3V Arduino pin
- note that Waveshare boards with "clever" reset circuit may need shortened reset pulse
- use
init(115200, true, 2, false)
for Waveshare boards with "clever" reset circuit - note that Waveshare boards with "clever" reset circuit need 1k pull-up on RST on ESP8266, or different pin
- note that the new Waveshare Universal e-Paper Raw Panel Driver HAT Rev 2.3 needs PWR connected to VCC or driven HIGH
- see https://www.waveshare.com/wiki/E-Paper_Driver_HAT
- This library uses paged drawing to limit RAM use and cope with missing single pixel update support
- buffer size can be selected in the application by template parameter page_height, see GxEPD2_Example
- Paged drawing is implemented as picture loop, like in U8G2 (Oliver Kraus)
- see https://github.com/olikraus/u8glib/wiki/tpictureloop
- Paged drawing is also available using drawPaged() and drawCallback(), like in GxEPD
// GxEPD style paged drawing; drawCallback() is called as many times as needed
void drawPaged(void (*drawCallback)(const void*), const void* pv)
- paged drawing is done using Adafruit_GFX methods inside picture loop or drawCallback
- full screen buffer is selected by setting template parameter page_height to display height
- drawing to full screen buffer is done using Adafruit_GFX methods without picture loop or drawCallback
- and then calling method display()
- bitmap drawing support to the controller memory and screen is available:
- either through the template class instance methods that forward calls to the base display class
- or directly using an instance of a base display class and calling its methods directly
- Waveshare e-paper displays with SPI: http://forum.arduino.cc/index.php?topic=487007.0
- Good Display ePaper for Arduino : https://forum.arduino.cc/index.php?topic=436411.0
- Note that these topics are closed. Use only for reference.
- create a new topic for each question or issue in https://forum.arduino.cc/c/using-arduino/displays/23
- GxEPD2_4G uses Adafruit_GFX for Graphics and Text support, which is well documented there
- GxEPD2_4G uses meaningful method names, and has some comments in the header files
- consult the header files GxEPD2_4G_BW.h, GxEPD2_4G_4G.h and GxEPD2_4G_GFX.h
- for the concept of paged drawing and picture loop see:
- https://github.com/olikraus/u8glib/wiki/tpictureloop
- issues should be reported in the Arduino Forum Displays.
- issues on GitHub are disabled; there were too many false issues.
- pull requests are not welcome, will not be merged.
- pull requests can't be disabled, but will be closed.
- please place information about interesting fork additions in the Arduino Forum Displays.
- GDEY0154D67 1.54" b/w 200x200, SSD1681
- GDEW0213I5F 2.13" b/w 104x212, UC8151 (IL0373), flexible
- GDEY0213B74 2.13" b/w 122x250, SSD1680
- GDEW027W3 2.7" b/w 176x264, EK79652 (IL91874)
- GDEW029T5 2.9" b/w 128x296, UC8151 (IL0373)
- GDEW029T5D 2.9" b/w 128x296, UC8151D
- GDEW029I6FD 2.9" b/w 128x296, UC8151D, flexible
- GDEM029T94 2.9" b/w 128x296, SSD1680
- GDEW0371W7 3.7" b/w 240x416, UC8171 (IL0324)
- GDEW042T2 4.2" b/w 400x300, UC8176 (IL0398)
- GDEY042T81 4.2" b/w 400x300, SSD1683
- GDEQ0426T82 4.26" b/w 800x480, SSD1677
- GDEW075T7 7.5" b/w 800x480, EK79655 (GD7965)
- added support for GDEY0154D67 200x200
- added support for GDEY0213B74 122x250
- added support for GDEY042T81 400x300
- added support for GDEQ0426T82 480x800
- added support for mixed b/w and 4G content, fast b/w partial refresh on grey background
- added classes GxEPD2_4G_BW_R and GxEPD2_4G_4G_R, for reference to common driver class
- added example GxEPD2_4G_MixedExample to show use of fast b/w on grey
- mixed content is experimental
- mixed content with fast b/w refresh can't be used with GDEM029T94
- added option to select an alternate HW SPI channel and/or SPI settings
- by method selectSPI(SPIClass& spi, SPISettings spi_settings) of driver base class GxEPD2_4G_EPD
- by calling selectSPI before calling init() of display class
- or by calling extended init() method that has these parameters added
- tested with RPi Pico RP2040 using Good Display DESPI-PICO connection shield
- updated GxEPD2_4G_Example to show use with DESPI-PICO
- DESPI-PICO: see https://www.good-display.com/product/393.html
- added optional init parameter "reset_duration" in ms
- reset_duration = 2 may help with "clever" reset circuit of newer boards from Waveshare
- changed the default reset duration to 10ms instead of 20ms
- changed the delay after reset to 10ms or reset duration, whichever is higher, instead of 200ms
- added a busyCallback feature, to allow to service periodic actions during wait for BUSY termination
// register a callback function to be called during _waitWhileBusy continuously.
void setBusyCallback(void (*busyCallback)(const void*), const void* busy_callback_parameter = 0);
- added some updates to solve compiler warnings (ALL for GCC for AVR)
- fix for STM32 official package pin number range (int16_t)
- fix for refresh(int16_t x, int16_t y, int16_t w, int16_t h) methods screen intersection
- added support for GDEW029T5D
- added support for GDEW029I6FD
- added support for GDEM029T94
- GDEM029T94 has no partial refresh with grey refresh mode
- improved handling of switching between refresh modes
- renamed top level files and classes to allow co-existence of installed GxEPD2_4G and GxEPD2
- fixed drawGreyPixmap() issues
- additional fixes
- added method drawGreyPixmap() to buffered graphics
- void drawGreyPixmap(const uint8_t pixmap[], int16_t depth, int16_t x, int16_t y, int16_t w, int16_t h);
- added support for GDEW075T7
- GDEW075T7 uses same wavetable as the other ones, no "official" (demo) yet
- GDEW075T7 grey level behaviour is less good than e.g. on GDEW0371W7
- some fixes and improvements
- initial version for 4 grey level support, experimental
- (slow) partial refresh doesn't work with 4G on some panels