Register Descriptions; System Memory Control Registers; Screen Starting Address Register (Ssa); Virtual Page Width Register (Vpw) - Motorola DragonBall MC68328 User Manual

4.7 REGISTER DESCRIPTIONS

4.7.1 System Memory Control Registers

4.7.1.1 SCREEN STARTING ADDRESS REGISTER (SSA).

31 30 29 28
SSA31 SSA30 SSA29 SSA28
15 14 13 12
SSA15 SSA14 SSA13 SSA12
Address: $(FF)FFFA00
SSA31-SSA1
32-bit screen-starting address of the LCD panel (see Figure 4-8). The LCDC fetches pixel
data from system memory at this address.

4.7.1.2 VIRTUAL PAGE WIDTH REGISTER (VPW).

VP8-VP0M Virtual Page Width Register
This register (see Figure 4-9) specifies the virtual page width of the LCD panel in terms of
byte count. VP0 defaults to zero because of the 16-bit transfers.
VPW = virtual page width in pixels divided by c where c is 16 for black-and-white display
and 8 for gray level.

4.7.2 Screen Format Registers

4.7.2.1 SCREEN WIDTH REGISTER (XMAX).

15 14 13 12
UNUSED
Address: $(FF)FFFA08
MOTOROLA MC68328 DRAGONBALL PROCESSOR USER'S MANUAL
27 26 25
SSA27 SSA26 SSA25
11 10 9
SSA11 SSA10 SSA9
Figure 4-8. Screen Starting Address Register
Screen-Starting Address Register
7 6 5
VP8 VP7 VP6
Address: $(FF)FFFA05
Figure 4-9. Virtual Page Width Register
11 10 9
XM9
Figure 4-10. Screen Width Register XMAX
24 23 22 21
SSA24 SSA23 SSA22 SSA21
8 7 6 5
SSA8 SSA7 SSA6 SSA5
4 3 2 1
VP5 VP4 VP3 VP2
Reset Value: $FF
8 7 6 5
XM8 XM7 XM6 XM5
LCD Controller
20 19 18 17
SSA20 SSA19 SSA18 SSA17
4 3 2 1
SSA4 SSA3 SSA2 SSA1
Reset Value: $00000000
0
VP1
4 3 2 1
XM4 XM3 XM2 XM1
Reset Value: $03FF
16
SSA16
0
0
0
XM0
4-13