RA8806
Preliminary Version 1.0
Two Layers Character/Graphic LCD Controller
6-3 Display Data RAM (DDRAM)
The RA8806 embedded two 9.6Kbyte Display Data RAMs – DDRAM1 and DDRAM2. It can use for two
layers mono-display or one layer 4-gray-levels display. The maximum resolution of supporting LCD
panel is 320Column x 240Row. There are two modes to write the DDRAM, text mode and graphics
mode. It provides a flexible and easy way to make the display.
6-3-1 Display Layer and Display Mode Selection
There are 4 possible displays way at 2 Modes combination.
1. Only show DDRAM1 or DDRAM2: One DDRAM data will show on the screen, and another one
DDRAM can be standby or as a CGRAM to created special font or symbol by users. Please refer
to Section 6-11 “User Defined Font” for detail description.
2. Two Layer Mode: In this mode, the screen will show the combination data of DDRAM1 and
DDRAM2. There are 4 types combination that set by REG[12H] Bit[3:2].
DDRAM1 “OR” DDRAM2
DDRAM1 “XOR” DDRAM2
DDRAM1 “NOR” DDRAM2
DDRAM1 “AND” DDRAM2
For detail please refer to Section 6-10-1-5 “Two Layer Display”.
3. 4-Gray-level Mode: In gray mode, each pixel consists with 2 continuous bits in both DDRAM.
4. Extension Mode: Two extension modes is support, and both DDRAM1 and DDRAM2 data will
show on the screen.
Horizontal extension mode (Max. resolution is 640 x 240 pixels).
Vertical extension mode (Max. resolution is 320 x 480 pixels).
6-3-2 Access Memory Selection
There are one 512Byte CGRAM and two 9.6KByte DDRAMs in RA8806. The 512Byte CGRAM is
used to generate user-define font, and the two DDRAM are used to store the display data. One of
both DDRAM can be also store special font or symbol, that when only one DDRAM is active on the
screen. Which RAM is available for MPU access is depending on the REG[12h] Bit[1:0]. Please
refer to Section 5-2 “Register Description”.
Table 6-9
Reg.
Bit_Num
Description
Reference
Display Layer and Display Mode Selection
Bit [6:4]
Bit [3:2]
Bit [1:0]
MAMR
REG[12h]
Two Layer Mode Selection
MPU Read/Write Memory Selection
RAiO TECHNOLOGY INC.
39/174
www.raio.com.tw
RAIO [ RAIO TECHNOLOGY INC. ]
