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Programming Notes and Examples S1D13504
Issue Date: 01/02/01 X19A-G-002-07
3.3 Look-Up Table (LUT)
This section provides a description of the LUT registers, followed by a description of the color and
gray shade LUTs and a discussion of the banks available in the 2 and 8 bit-per-pixel (bpp) modes.
The S1D13504 LUT is only used for the panel interface. The optional RAMDAC is used to
determine the colors for the CRT. See Section 6, “CRT Considerations” on page 33.
3.3.1 Look-Up Table Registers
The S1D13504 LUT Registers are located at offsets 24h, 26h and 27h. They consist of a LUT
address register, data register and bank register. Refer to the S1D13504 Hardware Functional Speci-
fication document number X19A-A-002-xx for more details.
RGB Index
Selects which LUT to program. If set for Auto-increment, it will start at the Red LUT of the Index
selected. Then with consecutive writes/reads it will increment to Green, then Blue of the same index,
it will then increment the index and start at the Red LUT again.
Auto-increment algorithm:
1. Set RGB Index to 0 for Auto-increment, set LUT address to 0 (i.e. REG[24h]=00h).
2. While count < or = to (16*3), write data byte to REG[26h].
R, G or B Index select algorithm:
1. Set RGB Index to R(01b), G(10b), or B(11b), set LUT address to 0 (e.g.
REG[24h]=10h).
2. While count < or = 16, write data byte to REG[26h], increment LUT address.
LUT Address
Selects start index of the LUT in which to read data from, or write data to. Bank select has no effect
on the CPU read/write to the LUT.
LUT Data
4-bit data value to write.
REG[24h] Look-Up Table Address Register Read/Write
n/a n/a RGB Index
Bit 1 RGB Index
Bit 0 LUT Address
Bit 3 LUT Ad dress
Bit 2 LUT Address
Bit 1 LUT Address
Bit 0
REG[26h] Look-Up Table Data Register Read/Write
n/an/an/an/aLUT Data
Bit 3 LUT Da ta
Bit 2 LUT Data
Bit 1 LUT Data
Bit 0
REG[27h] Look-Up Table Bank Register Read/Write
n/a n/a Red Bank
Select Bit 1 Red Bank
Select Bit 0 Blue Bank
Select Bit 1 Blue Bank
Select Bit 0 Green Bank
Select Bit 1 Green Bank
Select Bit 0