CS4954 datasheet(16/56 Pages) CIRRUS

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CS4954 CS4955

DS278PP4

PROG_VS Register (0x0D). VSYNC can be de-

layed by thirteen lines or advanced by eighteen lines.

5.2.3. Vertical Timing

The CS4954/5 can be configured to operate in any

of four different timing modes: PAL, which is 625

vertical lines, 25 frames per second interlaced;

NTSC, which is 525 vertical lines, 30 frames per

second interlaced; and either PAL or NTSC in Pro-

gressive Scan, in which the display is non-inter-

laced.

These

modes

are

selected

the

CONTROL_0 Register (0x00).

The CS4954/5 conforms to standard digital decom-

pression dimensions and does not process digital

input data for the active analog video half lines as

they are typically in the over/underscan region of

televisions. 240 active lines total per field are pro-

cessed for NTSC, and 288 active lines total per

field are processed for PAL. Frame vertical dimen-

sions are 480 lines for NTSC and 576 lines for

PAL. Table 2 specifies active line numbers for both

NTSC and PAL. Refer to Figure 6 for HSYNC,

VSYNC and FIELD signal timing.

5.2.4. Horizontal Timing

HSYNC is used to synchronize the horizontal-in-

put-to-output timing in order to provide proper hor-

izontal alignment. HSYNC defaults to an input pin

following RESET but switches to an output in Mas-

ter Mode (CONTROL_0 [4] = 1). Horizontal tim-

ing is referenced to HSYNC transitioning low. For

active video lines, digital video input is to be ap-

plied to the V [7:0] inputs for 244 (NTSC) or for

264 (PAL) CLK periods following the leading

(falling) edge of HSYNC if the PROG_HS Regis-

ters are set to default values.

5.2.5. NTSC Interlaced

The CS4954/5 supports NTSC-M, NTSC-J and

PAL-M modes where there are 525 total lines per

frame and two fixed 262.5-line fields per frame and

30 total frames occurring per second. NTSC inter-

laced vertical timing is illustrated in Figure 7. Each

field consists of one line for closed caption, 240 ac-

tive lines of video, plus 21.5 lines of blanking.

VSYNC field one transitions low at the beginning

of line four and will remain low for three lines or

2574 pixel cycles (858 × 3). The CS4954/5 exclu-

sively reserves line 21 of field one for closed cap-

tion insertion. Digital video input is expected to be

delivered to the CS4954/5 V [7:0] pins for 240

lines beginning on active video lines 22 and con-

tinuing through line 261. VSYNC field two transi-

tions low in the middle of line 266 and stays low for

three line-times and transitions high in the middle

of line 269. The CS4954/5 exclusively reserves line

284 of field two for closed caption insertion. Video

input on the V [7:0] pins is expected between lines

285 through line 525.

5.2.6. PAL Interlaced

The CS4954/5 supports PAL modes B, D, G, H, I,

N, and Combination N, in which there are 625 total

lines per frame, two fixed 312.5 line fields per

frame, and 25 total frames per second. Figure 8 il-

lustrates PAL interlaced vertical timing. Each field

consists of 287 active lines of video plus 25.5 lines

of blanking.

VSYNC will transition low to begin field one and

will remain low for 2.5 lines or 2160 pixel cycles

(864 × 2.5). Digital video input is expected to be

delivered to the CS4954/5 V [7:0] pins for 287

lines beginning on active video line 24 and continu-

ing through line 310.

Field two begins with VSYNC transitioning low

after 312.5 lines from the beginning of field one.

Mode

Field

Active Lines

NTSC

1, 3;

2, 4

22-261;

285-524

PAL

1, 3, 5, 7;

2, 4, 6, 8

23-310;

336-623

NTSC Progressive-Scan

22-261

PAL Progressive-Scan

23-310

Table 2. Vertical Timing

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