ch7004c Chrontel, ch7004c Datasheet - Page 36

• Manufacturer Part Number: ch7004c
• Description: Digital Pc To Tv Encoder With Macrovisiontm
• Manufacturer: Chrontel

CHRONTEL
Vertical Position Register
This register is used to shift the displayed TV image in a vertical direction (up or down) to achieve a vertically cen-
tered image on screen. This bit field, VP[8:0] represents the TV line number (relative to the VGA vertical sync)
used to initiate the generation and insertion of the TV vertical interval (i.e., the first sequence of equalizing pulses).
Increasing values delay the output of the TV vertical sync, causing the image position to move UP on the TV screen.
Decreasing values, therefore, move the image position DOWN. Each increment moves the image position by one
TV lines (approximately 4 input lines). The maximum value that should be programmed into the VP[8:0] value is
the number of TV lines minus one, divided by two (262, 312 or 313). When panning the image up, the number
should be increased until (TVLPF-1) /2 is reached; the next step should be to reset the register to zero. When pan-
ning the image down the screen, the VP[8:0] value should be decremented until the value zero is reached. The next
step should set the register to (TVLPF-1) /2, and then decrementing can continue. If this value is programmed to a
number greater than (TV lines per frame-1) /2, a TV vertical SYNC will not be generated.
Sync Polarity Register
This register provides selection of the synchronization signal input to, or output from, the CH7004.
Note: When sync direction is set to be an output, horizontal sync will use a fixed pulse width of 64 pixels and vertical
sync will use a fixed pulse width of 2 lines.
36
Bit:
Symbol:
Type:
Default:
Bit:
Symbol:
Type:
Default:
• HSP (bit 0) is Horizontal Sync Polarity - an HSP value of zero means the horizontal sync is active low, and a
• VSP (bit 1) is Vertical Sync Polarity - a VSP value of zero means the vertical sync is active low, and a value of
• SYO (bit 2) is Sync Direction - a SYO value of zero means that H and V sync are input to the CH7004. A
• DES (bit 3) is Detect Embedded Sync - a DES value of zero means that H and V sync will be obtained from
value of one means the horizontal sync is active high.
one means the vertical sync is active high.
value of one means that H and V sync are output from the CH7004.
the direct pin inputs. A DES value of one means that H and V sync will be detected from the embedded codes
on the pixel input stream. Note that this will only be valid for the YCrCb input modes.
7
VP7
R/W
0
7
6
VP6
R/W
0
6
5
VP5
R/W
0
5
4
VP4
R/W
0
4
3
VP3
R/W
0
3
DES
R/W
0
201-0000-024 Rev. 2.4, 6/24/2004
2
VP2
R/W
0
2
SYO
R/W
0
Symbol: VPR
Address: 0BH
Bits: 8
Address: 0DH
Bits: 4
Symbol: SPR
1
VP1
R/W
0
1
VSP
R/W
0
CH7004C
0
VP0
R/W
0
0
HSP
R/W
0