* Support for **GDEH029A1** / **SSD1608** based ePaper modules in 4-wire SPI mode. Support for other controllers will be added later
* **emulated** 4-bit gray scale mode
* **SPI displays oriented SPI driver library** based on *spi-master* driver
* Combined **DMA SPI** transfer mode and **direct SPI** for maximal speed
* **4-bit Grayscale mode** or **1-bit b/w mode** can be selected during runtime
* SPI speeds up to **20 MHz** are tested and works without problems
* **Demo application** included which demonstrates most of the library features
* **Graphics drawing functions**:
* **EPD_drawPixel** Draw pixel at given x,y coordinates
* **EPD_drawLine** Draw line between two points
* **EPD_drawFastVLine**, **EPD_drawFastHLine** Draw vertical or horizontal line of given lenght
* **EPD_drawLineByAngle** Draw line on screen from (x,y) point at given angle
* **EPD_drawRect**, **EPD_fillRect** Draw rectangle on screen or fill given rectangular screen region with color
* **EPD_drawRoundRect**, **EPD_fillRoundRect** Draw rectangle on screen or fill given rectangular screen region with color with rounded corners
* **EPD_drawCircle**, **EPD_fillCircle** Draw or fill circle on screen
* **EPD_drawEllipse**, **EPD_fillEllipse** Draw or fill ellipse on screen
* **EPD_drawTriangel**, **EPD_fillTriangle** Draw or fill triangle on screen
* **EPD_drawArc** Draw circle arc on screen, from ~ to given angles, with given thickness. Can be outlined with different color
* **EPD_drawPolygon** Draw poligon on screen with given number of sides (3~60). Can be outlined with different color and rotated by given angle.
* **Fonts**:
* **fixed** width and proportional fonts are supported; 8 fonts embeded
* unlimited number of **fonts from file**
* **7-segment vector font** with variable width/height is included (only numbers and few characters)
* Proportional fonts can be used in fixed width mode.
* Related functions:
* **EPD_setFont** Set current font from one of embeded fonts or font file
* **EPD_getfontsize** Returns current font height & width in pixels.
* **EPD_getfontheight** Returns current font height in pixels.
* **set_7seg_font_atrib** Set atributes for 7 segment vector font
* **getFontCharacters** Get all font's characters to buffer
* **String write function**:
* **EPD_print** Write text to display.
* Strings can be printed at **any angle**. Rotation of the displayed text depends on *font_ratate* variable (0~360)
* if *font_transparent* variable is set to 1, no background pixels will be printed
* If the text does not fit the screen/window width it will be clipped ( if *text_wrap=0* ), or continued on next line ( if *text_wrap=1* )
* Two special characters are allowed in strings: *\r* CR (0x0D), clears the display to EOL, *\n* LF (ox0A), continues to the new line, x=0
* Special values can be entered for X position:
* *CENTER* centers the text
* *RIGHT* right justifies the text horizontaly
* *LASTX* continues from last X position; offset can be used: *LASTX+n*
* Special values can be entered for Y:
* *CENTER* centers the text verticaly
* *BOTTOM* bottom justifies the text
* *LASTY* continues from last Y position; offset can be used: *LASTY+n*
* **EPD_getStringWidth** Returns the string width in pixels based on current font characteristics. Useful for positioning strings on the screen.
* **EPD_clearStringRect** Fills the rectangle occupied by string with current background color
* **Images**:
* **EPD_jpg_image** Decodes and displays JPG images
* Limits:
* Baseline only. Progressive and Lossless JPEG format are not supported.
* Image size: Up to 65520 x 65520 pixels
* Color space: YCbCr three components only. Gray scale image is not supported.
* Sampling factor: 4:4:4, 4:2:2 or 4:2:0.
* Can display the image **from file** or **memory buffer**
* Image can be **scaled** by factor 0 ~ 3 (1/1, 1/2, 1/4 or 1/8)
* Image is displayed from X,Y position on screen/window:
* X: image left position; constants CENTER & RIGHT can be used; *negative* value is accepted
* Y: image top position; constants CENTER & BOTTOM can be used; *negative* value is accepted
* Image is converted to **4-bit Gray Scale mode**
* **Other display functions**:
* **EPD_fillScreen** Fill the whole screen with black, white or gray scale
* **compile_font_file** Function which compiles font c source file to font file which can be used in *EPD_setFont()* function to select external font. Created file have the same name as source file and extension *.fnt*
* **Global wariables**
* **orientation** current screen orientation
* **font_ratate** current font rotate angle (0~395)
* **font_transparent** if not 0 draw fonts transparent
* **font_forceFixed** if not zero force drawing proportional fonts with fixed width
* **text_wrap** if not 0 wrap long text to the new line, else clip
* **_fg** current foreground color for fonts
* **_bg** current background for non transparent fonts
* **_angleOffset** angle offset for arc, polygon and line by angle functions
* **image_debug** print debug messages during image decode if set to 1
* **cfont** Currently used font structure
* **EPD_X** X position of the next character after EPD_print() function
* **EPD_Y** Y position of the next character after EPD_print() function
* **_gs** use 4-bit Gray scale if set to 1
* **_width** screen width (larger dimension) in pixels
* **_height** screen height (smaller dimension) in pixels
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Full functions **syntax and descriptions** can be found in *EPD.h* and *EPDspi.h* files.
Full **demo application**, well documented, is included, please **analyze it** to learn how to use the library functions.
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#### Connecting the display
To run the demo, attach display module to ESP32. Default pins used are:
* mosi: 23
* sck: 18
* CS: 5 (display CS)
* DC: 26 (display DC)
* RST: 27 (display RESET)
* BUSY: 32 (display BUSY output)
The display can be powered from 3.3V or from **GPIO pin**. See *EPDspi.h* for configuration options.
**If you want to use different pins, change them in** *EPDspi.h*
Using *make menuconfig***select tick rate 1000** ( → Component config → FreeRTOS → Tick rate (Hz) ) to get more accurate timings
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#### How to build
Configure your esp32 build environment as for **esp-idf examples**
