Epson Research and Development
Page 21
Vancouver Design Center
Programming Notes and Examples
S1D13503
Issue Date: 01/01/30
X18A-G-002-06
RGB Index bits [1:0]: These bits are also used to provide access to the three internal Look-Up Tables
(RGB).
Note
When auto-increment is selected, an internal pointer will default to the Red palette on
power on reset. Each read/write access to Aux[0F] will increment the counter to point
to the next palette in order (RGB). Whenever the Look-Up Table Address register
Aux[0E} is written, the RGB Index will reset the pointer to the Red palette. This pro-
vides a efficient method for sequential writing of RGB data.
bits 3-0
Palette Address Bits [3:0]
These 4 bits provide a pointer into the 16 position Look-Up Table currently selected for CPU R/W access.
Note
The Look-Up Table configuration (e.g. 1/2/4 banks) does not affect the R/W access
from the CPU. All 16 positions can be accessed sequentially.
bit 7-6
Red Bank Bits [1:0]
In 4-level color display modes, the 16 position Red palette is arranged into four, 4 position “banks”. These
two bits control which bank is currently selected.
In 256 color display modes, the 16 position, Red palette is arranged into two, 8 position “banks” for the
display of “red” colors. Only bit 0 of these two bits controls which bank is currently selected.
These bits have no effect in all gray shade or 16-color display modes.
bit 5-4
Blue Bank Bits [1:0]
In both the 4 and 256 color display modes, the 16 position Blue palette is arranged into four 4 position
“banks” for the display of “blue” colors. These two bits control which bank is currently selected.
These bits have no effect in all gray shade display modes or 16 color display modes.
bits 3-0
Palette Data Bits [3:0]
These 4-bits are the gray shade / color values used for display data output. They are programmed into the
4-bit Look-Up Table (palettes) positions pointed to by Palette Address bits [3:0] and RGB Index bit[1:0]
(if in color display modes).
For example; in a 16-level gray shade display mode, a data value of 0001b (4-bits / pixel) will point to
Look-Up Table position one and display the 4-bit gray shade corresponding to the value programmed into
that location.
Table 3-3: Look-Up Table Access
Aux[0E]
Look-Up Table Access
bit 5
bit 4
0
0
Auto-increment (see Note 1)
0
1
Red palette R/W access
1
0
Green palette R/W access
1
1
Blue palette R/W access
AUX[0F] Look-Up Table Data Register
I/O address = 1111b, Read/Write.
Red Bank
Bit 1
Red Bank
Bit 0
Blue Bank
Bit 1
Blue Bank
Bit 0
Palette Data
Bit 3
Palette Data
Bit 2
Palette Data
Bit 1
Palette Data
Bit 0
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