AL875

Preliminary version subject to change without notice

January 25, 2001

17

The whole frame detection scans the whole input video/graphics to check in which range the luma data

is larger than the threshold value defined by DATA_TH or VDATA_TH. Any luma data lower than

the threshold value is considered blanking period. Whole frame detection may be more accurate than

1-line detection. The following drawing shows the related registers:

INPUT

ACTIVE

REGION

HSYNC

Selected line for vertical positioning detection

VCOLUMN, #19h

Selected line for horizontal

positioning detection

HNUMBER, #10h

VDE_ST,

#1Ah<2:0> & 1Bh<7:0>

HCNT_TOT,

#16h<2:0> & #17h<7:0>

HDE_END,

#14h<2:0> & #15h<7:0>

VDE_END,

#1Ch<2:0> & #1Dh<7:0>

HDE_ST,

#12h<2:0>

& #13h<7:0>

HS_WIDTH, #18h<7:0>

Threshold = DATA_TH, #11h

When horizontal and vertical thresholds are different:

Threshold horizontal = DATA_TH, #11h

Threshold vertical = VDATA_TH, #0Fh, Enabled by #06h<7>

AL875-09 One-line position detection