26 LCD CONTROLLER (LCDC)
26-2
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
Display features
• Picture-in-Picture Plus to display a variable size window overlaid over background image.
• Virtual display function to handle images with a different resolution from the LCD panel (any area in the vir-
tual screen can be displayed on the LCD.)
Clock
• LCLK for the LCD controller is generated in the CMU by dividing the OSC3 clock by 1 to 32.
• Different clock paths are provided for the AHB bus interface (for accessing the VRAM), SAPB interface
(for accessing the control registers), and LCLK, and each clock supply can be controlled individually in the
CMU. This makes it possible to reduce current consumption by disabling unnecessary clocks.
Power save
• Software power-save mode
• Blank display
Block Diagram
26.2
IVRAM
interface
Arbiter
Bus controller
(Bus arbiter)
IVRAM
(20KB)
SAPB
bus interface
Look-up
table
LCDC cache
Sequence
controller
Registers
Power save
circuit
SAPB bridge
GE
CMU
AHB
bus interface
SDRAM/
SRAM
LCD
interface
FPDAT[23:0]
FPFRAME
FPLINE
FPSHIFT
FPDRDY
TFT_CTL[3:0]
To LCD panel
LCDC clocks
LCD Controller
S1C33L26
AHB-1
AHB-2
2.1 LCD Controller Block Diagram
Figure 26.
SAPB bus interface
The C33 PE Core accesses the LCDC registers and monochrome look-up table through this interface.
AHB bus interface
The LCDC access the VRAM through this interface.
LCDC cache
This consists of two 32-byte FIFOs used as a display data cache for sending display data to the LCD panel.
Sequence controller
The sequence controller controls data flow from the AHB bus interface to the LCD interface through the color
look-up table. It also generates display data memory addresses for refreshing display.
Look-up table
In color mode, the LCDC uses LUTRAM (switched from DSTRAM via software) as the color look-up table
(LUT). This consists of three tables (256
×
5 bits for red, 256
×
6 bits for green, and 256
×
5 bits for blue) and
is used to set up color data to be displayed.