NEC uPD72257, Preliminary User'S Manual

Page: 185 / 343

6.10.2.13 VInSCANLINE - Active scanline register
This register holds the current unscaled scanline number. It is reset with every
VSYNC.
Access This register can be read in 32-bit units.
Address <VIn_Base> + 24
H
Initial Value 0000 0000
H
. This register is initialized by any reset and VSYNC.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
R R R R R R R R R R R R R R R R
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 0 AFLD ACTSL[11:0]
R R R R R
Bit Bit name Function
12 AFLD
Current status of the internal field signal
0 first field
1 second field
11 to 0 ACTSL[11:0] Current scanline number of the current field AFLD
Note
In progressive scan mode, the scanline counter counts from 0 to field_height-1.
In interlaced scan mode, the scanline counter counts from 0 to (field_height/2)-1.
"field_height" denotes the the number of lines of the field to capture.
Video Input (Ravin-M only) Chapter 6
Preliminary User's Manual S19203EE1V3UM00
185