SED1354 Datasheet, PDF (118/472 Pages) Epson Company – Color Graphics LCD/CRT Controller

Page 110
Epson Research and Development
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Performance Enhancement Register 1
REG[23h]
Display FIFO
Disable
n/a
n/a
Display FIFO Display FIFO Display FIFO Display FIFO Display FIFO
Threshold
Threshold
Threshold
Threshold
Threshold
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
bit 7
bits 4-0
Display FIFO Disable
When this bit = 1 the display FIFO is disabled and all data outputs are forced to zero (i.e. the screen
is blanked). This allows the SED1354 to be dedicated to service CPU to memory accesses. When
this bit = 0 the display FIFO is enabled.
Display FIFO Threshold Bits [4:0]
These bits should be set to a value of 10h upon initialization as this provides the best overall perfor-
mance for all display modes.
8.2.8 Look-Up Table Registers
The SED1354 has three internal 16 position, 4-bit wide Look-Up Tables. The 4-bit value
programmed into each table position determines the color weighting of display data; the output gray
shade is derived from the Green Look-Up Table. These tables are bypassed in 15/16-bpp mode.
These three 16 position Look-Up Tables can be arranged in many different configurations to accom-
modate all the gray shade / color display modes.
Look-Up Table Address Register
REG[24h]
n/a
n/a
RGB Index
Bit 1
RGB Index
Bit 0
RW
LUT Address LUT Address LUT Address LUT Address
Bit 3
Bit 2
Bit 1
Bit 0
bits 5-4
RGB Index Bits [1:0]
These bits are also used to provide access to the three internal Look-Up Tables (RGB).
RGB Index Bits [1:0]
00
01
10
11
Table 8-15: RGB Index Selection
Look-Up Table Access
Auto-Increment R, G, B LUT
Auto-Increment Red LUT only
Auto-Increment Green LUT only
Auto-Increment Blue LUT only
Pointer Sequence
R[n], G[n], B[n], R[n+1], G[n+1] . . .
R[n], R[n+1], R[n+2] . . .
G[n], G[n+1], G[n+2] . . .
B[n], B[n+1], B[n+2] . . .
A write to this register with RGB Index bits = 00 selected will position the internal pointer to the
Red LUT. Each read/write access to the LUT data will increment the counter to point to the next
LUT in order (R to G to B to R...). A read/write access to the Blue LUT will also automatically
increment the LUT address by 1. This provides an efficient method for sequential writing of RGB
data.
When the RGB Index bits = 01, 10, or 11, the internal pointer always points to the respective R, G,
or B LUT. A read/write access to the LUT data will increment the LUT address by 1.
SED1354
X19A-A-002-16
Hardware Functional Specification
Issue Date: 99/05/18