Interfacing Atmel AVR with Graphics Liquid Crystal Displays (GLCDs)

AVR SED1520 Library

This is a C-library for avr-gcc/avr-libc to access SED1520-based graphics-LCDs. The modules used to develop the library only support “write to LCD”, read-modify- write on the display RAM is not possible. So this Library uses a “frame buffer” which holds the display-content in the AVR’s SRAM. For a 122*32 pixel display around 500 Bytes of SRAM are occupied by the buffer. The library does of cause support modules which can be read in “write-only-mode” (tie the R/W-Pin to GND).
The library supports:

  • Dots (set/clear/toogle)
  • Lines (set/clear/toogle)
  • Circles (set/clear/toogle)
  • Rects/Boxes (set/clear/toogle)
  • Fonts in different sizes (included)
  • Draw Bitmaps (“Icons”)


  • Michal J. Kara’s ( Overall concept from his C51-libraries for other graphic-controllers, glyph/font-handling based on his code.
  • Fabian “ape” Thiele: the line/circle-routines are from his KS0108-Library


The library has been tested with an ATmega32 (8MHZ int. R/C) and an Emerging Displays EW12A03GLY Module (2 SED1520, 122*32 pixels, google for datasheet).


The source-code has been part of my “Will there ever be a request for a commercial license if the source-code is provided”-experiment. This experiment is now halted. The source-code is currently not available. Everybody who has downloaded the source is still bound to the non-commercial license. The only exception are users who have received my permission for a commercial use.

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