Driver epd.c, fonts from https://www.mikrocontroller.net/topic/54860.

Code page 850

EPD and SPI Words

epd-emit works like the standard word emit. It blocks the calling thread, as long as the character is not written to the EPD display. Horizontal (x) position is in pixel (0 to 249), vertical position (y) is in lines, a line consists of 8 pixels. Larger fonts takes more than one line.

epd-emit     ( Char -- )        Emits a character (writes a character to the EPD framebuffer)
epd-emit?    ( -- Flag )        EPD ready to get a character (SPI not busy)

hook-emit    ( -- a-addr )      Hooks for redirecting terminal IO on the fly
hook-emit?   ( -- a-addr )    

epdpos!      ( x y -- )         Set EPD cursor position, 
                                x horizontal position, for 6x8 font max. (250 / 6) -1, depends on the font's x size 
                                y vertical position (a line consists of 8 pixels), max. 14 for 255x122.
epdpos@      (  -- x y )        Get the current EPD cursor position
epdupdate    (  --  )           Update the display (copy the framebuffer to the display)
epdpartial   ( x1 y1 x2 y2 -- ) Partial update the display
epdcmd       ( c-addr -- )      Send command to the EPD controller SSD1680. First byte contains the length of the command.
epdclr       (  -- )            Clears the EPD display, sets the cursor to 0, 0
epdfont      ( u -- )           Select the font, u: 0 6x8, 1 8x8, 2 8X16 , 3 12X16

>epd         ( -- addr1 addr2 ) redirect to EPD
>term        ( addr1 addr2 -- ) terminate redirection

Usage

It is easy to redirect the terminal output to the EPD display, to use the string formatting words.

: epd-hallo (  -- )
  hook-emit @              \ save emit hook
  ['] epd-emit hook-emit !  \ redirect terminal to epd-emit
  ." Hallo Velo! " cr
  ." ciao"
  epdupdate
  hook-emit !         \ restore old hook
;

or even simpler

: epd-hallo (  -- )
  >epd         \ redirect terminal to epd-emit
  ." Hallo Velo! " cr
  ." ciao" 
  epdupdate
  >term         \ terminate redirection
;

or on a command line

>epd .( Hallo Velo!) epdupdate >term 

show date and time on EPD (see CmsisRtos#How_to_use_Tasks for a background task).

: clock (  -- )
  epdclr
  3 epdfont
  -1 -1 -1 alarm!  \ set an alarm every second
  begin
    wait-alarm     \ wait a second
    0 0 epdpos!
    >epd epdpos@ .time epdpos@ epdpart >term
  key? until
  key drop
;

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