AMD Geode LX 800@0.9W - Manual (Page 399)

AMD Geode™ LX Processors Data Book 399
Video Processor 33234H
6.7.6.3 HBLANK and VBLANK Signals
HBLANK and VBLANK signals are different from HSYNC
and VSYNC. The HSYNC and VSYNC signals are only
active for a portion of the blanking time, while the HBLANK
and VBLANK signals are active through the entire time.
HBLANK is a function of horizontal pixel position, while
VBLANK is a function of the vertical line number and the
horizontal pixel position. Figures 6-30 to 6-34 show the for-
mation of these signals using a 525-line NTSC video win-
dow.
Figure 6-30. 525-Line NTSC Video Window
Figure 6-31. HBLANK and VBLANK for Lines 20-262, 283-524
Pixel Position
Line Number
Frame 1
858
525
1
1
V = 1
V = 0
V = 1
V = 0
20
264
283
Frame 0 (continued)
Frame 0
Pixel Position
Line Number
HBLANK
VBLANK
720 721 858 001
L# L# + 1