
ViiiPeRiPheRaLMoDuLes6(LCD):LCDContRoLLeR(LCDC)
Viii-1-6
ePson
s1C33L17teChniCaLManuaL
Viii.1.4systemsettings
Viii.1.4.1ConfigurationofDisplayDataMemory(VRaM)
The S1C33L17 has a built-in 12K-byte display data memory (IVRAM). This memory allows selection whether it
is used as a VRAM by locating at 0x80000 to 0x82FFF in area 3 or a general-purpose RAM by locating in area 0.
Setting IRAM (D0/0x3001A64) to 1 configures the RAM as a general-purpose RAM in area 0; setting to 0 config-
ures it as a VRAM in area 3. At initial reset, this memory is located in area 3 as a VRAM allowing LCDC to access
directly.
*iRaM:IRAMAssignmentBitintheIRAMSelectRegister(D0/0x3001A64)
The LCDC can use an external SDRAM as a VRAM in addition to IVRAM (the SDRAM can store general-
purpose data as well as display data). There is no special configuration procedure for use of the external SDRAM.
Furthermore, both the external SDRAM and IVRAM can be used as VRAM simultaneously. The LCDC handles
two screen data for the main window and the sub-window overlaid over the main window to support “Picture-in-
Picture Plus.” Also the LCDC can switch the display by selecting a screen from two or more display data prepared
in the VRAM. Since the display start memory address is specified using a register, display data can be stored in any
location (but it must be a word boundary address) in the memory.
Figure VIII.1.4.1.1 shows memory usage examples.
IVRAM
SDRAM
Window
Main
Sub
WhenusingPicture-in-PicturePlus
IVRAM
SDRAM
Window
Main
Sub
IVRAM
SDRAM
Window
Main
Sub
IVRAM
SDRAM
Window
Main
Sub
Not
used
Ex.1
IVRAM
SDRAM
Window
Screen1
Window
Screen2
Whenswitchingscreens
Ex.5
Ex.2
Ex.3
Ex.4
SDRAM
Virtualscreen
Actualdisplaywindow
Whenusingvirtualscreenarea
Ex.7
IVRAM
SDRAM
Window
Screen1
Window
Screen2
Ex.6
Not
used
SDRAM
Virtualscreen
Actualdisplaywindow
FigureVIII.1.4.1.1MemoryUsageExamples
The memory size required for a screen depends on the screen size and bpp mode. It can be expressed by the follow-
ing equation:
Screendatasize=H_PIXEL
×V_PIXEL×bpp/32[words]
(The fractional portion of the number must be rounded up.)
H_PIXEL: Number of horizontal pixels
V_PIXEL: Number of vertical pixels
bpp:
Number of bits per pixel (1, 2, 4, 8, 12, 16)
For example, a 320
× 240-pixel screen displayed in 256 colors (8-bpp mode) needs a 19,200 words (75K bytes) of
memory area.