
Pre-Amplifier Interface Registers (Continued)
Bits 1–0
These determine the optimum frequency range of the Phase Locked Loop. Please see
Table 3 for
recommended register values as a function of horizontal scan rate and the Pixels per Line register,
0x8401[7:5].
Bit 2
This is the Vertical Blanking register. When this bit is a 1, vertical blanking is gated to the video outputs.
When set to a 0, the video outputs do not have vertical blanking.
Bit 3
This is the OSD override bit. This should be set to 0 for normal operation. When set to a 1, the video
outputs are disconnected and OSD only is displayed. This is useful for the OSD display of special
conditions such as “No Signal” and “Input Signal Out of Range”, to avoid seeing unsynchronized video.
Bit 4
Reserved and should be set to zero.
Bit 5
This is the Clamp Polarity bit. When set to a 0, the LM1247 expects a positive going clamp pulse.
When set to a 1, the expected pulse is negative going.
Bits 7–6
Reserved and should be set to zero.
Software Reset and Test Control:
SRTSTCTRL (0x843F)
Res’d
Reserved
Reset
X
AID
XXXXX
SRST
Bit 0
When this bit is a 1, all registers except this one are loaded with their default values. All operations are
aborted, except data transfers in progress on the I
2C compatible bus. This bit clears itself when the reset is
complete.
Bits 5–1
Reserved and should be set to zero.
Bit 6
This bit disables the register Auto-Increment feature of the I
2C compatible protocol. When set to a 1
Auto-Increment is disabled and when a 0, AI is enabled.
Bit 7
Reserved and should be set to zero.
Attribute Table and Enhanced Features
Each display character and SL in the Display Page RAM will have a 4-bit Attribute Table entry associated with it. The user should
note that two-color display characters and four-color display characters use two different Attribute Tables, effectively providing 16
attributes for two-color display characters and 16 attributes for four-color display characters.
For two-color characters the attribute contains the code for the 9-bit foreground color (Color 1), the code for the 9-bit background
color (Color 0), and the character’s enhanced features (Button Box, Blinking, Heavy Box, Shadowing, Bordering, etc.).
For four-color characters the attribute contains the code for the 9-bit Color 0, the code for the 9-bit Color 1, the code for the 9-bit
Color 2, the code for the 9-bit Color 3 and the character’s enhanced features (Button Box, Blinking, Heavy Box, Shadowing,
Bordering, etc.).
TWO COLOR ATTRIBUTE FORMAT
The address range for an attribute number, 0
ATT2C3n (0x8443+n*4)
ATT2C2n (0x8442+n*4)
Reserved
Enhanced Feature
Color 1 -
X
XXXXXXX
XX
EFB[3:0]
C1B[2:1]
ATT2C1n (0x8441+n*4)
ATT2C0n (0x8440+n*4)
Blue
Color 1 - Green
Color 1 - Red
Color 0 - Blue
Color 0 - Green
Color0-Red
C2B0
C1G[2:0]
C1R[2:0]
C0B[2:0]
C0G[2:0]
C0R[2:0]
Bits 8–0
These nine bits determine the background color (color1) which is displayed when the corresponding OSD
pixel is a 0.
Bits 17–9
These nine bits determine the foreground color (color2) which is displayed when the corresponding OSD pixel
isa1.
Bits 21–18
These are the enhanced feature (EF) bits which determine which feature is applied to the displayed character.
The features and their corresponding codes are shown in
Table 24.Bits 31–22
Reserved and should be set to zero.
LM1247
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