sed1355 ETC-unknow, sed1355 Datasheet - Page 171

• Manufacturer Part Number: sed1355
• Description: Sed1355 Embedded Ramdac Lcd/crt Controller
• Manufacturer: ETC-unknow

Epson Research and Development
Vancouver Design Center
4 Look-Up Table (LUT)
4.1 Look-Up Table Registers
Programming Notes and Examples
Issue Date: 99/04/27
REG[24h] Look-Up Table Address Register
REG[26h] Look-Up Table Data Register
LUT Address
LUT Data
Bit 7
Bit 3
LUT Address
LUT Data
Bit 6
Bit 2
This section is supplemental to the description of the Look-Up Table architecture found in the
SED1355 Hardware Functional Specification. Covered here is a review of the LUT registers, recom-
mendations for the color and gray shade LUT values, and additional programming considerations
for the LUT. Refer to the SED1355 Hardware Functional Specification, document number
X23A-A-001-xx for more detail.
The SED1355 Look-Up Table is used for both the CRT and panel interface and consists of 256
indexed red/green/blue entries. Each entry is 4 bits wide. Two registers, at offsets 24h and 26h,
control access to the LUT. Color depth affects how many indices will be used for image display.
In color modes, pixel values are used as indices to an RGB value stored in the Look-Up Table. In
monochrome modes only the green component of the LUT is used. The value in the display buffer
indexes into the LUT and the amount of green at that index controls the intensity. Monochrome
mode look-ups are done for the panel interface only. The CRT interface always receives the RGB
values from the Look-Up Table.
LUT Address
The LUT address register selects which of the 256 LUT entries will be accessed. Writing to this
register will select the red bank. After three successive reads or writes to the data register this register
will be incremented by one.
LUT Data
This register is where the 4-bit red/green/blue data value is written or read. With each successive
read or write the internal bank select is incremented. Three reads from this register will result in
reading the red, then the green, and finally the blue values associated with the index set in the LUT
address register.
After the third read the LUT address register is incremented and the internal index points to the red
bank again.
LUT Address
LUT Data
Bit 5
Bit 1
LUT Address
LUT Data
Bit 4
Bit 0
LUT Address
Bit 3
n/a
LUT Address
Bit 2
n/a
LUT Address
Bit 1
n/a
X23A-G-003-05
LUT Address
Read/Write
Read/Write
SED1355
Bit 0
n/a
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