The HD61830(B) graphics controller chip is designed to control small to medium size graphic Liquid Crystal Display modules (LCD). It may be interfaced with a number of different 8-bit micro-processor units (MPU). It provides the necessary interface between the MPU and the video RAM (VRAM), sometimes referred to as Display RAM or Refresh RAM. It also generates the necessary timing and data signals for the liquid crystal driver circuits. It has a built-in 192 character Character-Generator ROM (CG-ROM) and Character Generator (CG) circuits. The HD61830(B) has the capability to control upto 64K bytes of external display RAM in graphics mode and 4K bytes in the character mode. Most designs using the HD61830(B) only implement 2K to 8K of VRAM depending on the size of LCD screen. This VRAM may be allocated for text or graphics. The HD61830(B) can support a wide variety of LCD formats.
This application note is not written with any specific display in mind but is intended to give a thorough understanding of how to use the HD61830(B) and implement the software/hardware interface. Some LCD modules will have the HD61830(B) controller built into the module such as the LM31XX and LM41XX series of LCD modules, others require an external graphics controller. This application note is applicable to the LM1001GC, LM1002GC and LM1006GC graphics controller cards available from Densitron as well as to Densitron LCD modules with on-board HD61830(B) graphics controllers.
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