Those who have come across in their designs with the need to display a large amount of text on the display screen know how slow this happens, even if the exchange with the video controller is via a parallel bus.
The RA8875 video controller has the ability to connect an external EEPROM with fonts. Information about these EEPROMs can be viewed on the xlatb Github page . It is enough for the controlling microcontroller to switch the RA8875 to text mode and send a text, the output of this text occurs almost instantly.
EEPROM .
, RA8875 EEPROM W25Q32 . datasheet ER3304-1 , .
ASCII 96 , 16, 24 32 . ER3304-1 Arial Times , 96, Arial , Times . 3 , 16, 24 32 . «proportional adjusted», , EEPROM 34, 74 130 , ( , EEPROM ). , , 0x00, 0x0C 12 , , 16 . EEPROM :
- , . , , 16 32+2=34 .
BitFontCreator . HEX Python. , , . , . , , .
, - , hex .
When creating a font, it is necessary to shift the character image to the left so that you can crop the empty space by setting the required character width in pixels.
On Github, in addition to fonts, ready-made firmware and a utility for creating a hex file from asm, there is also a circuit and a printed circuit board of the display module. This module was created for eZ80f91.