Motorola MPC823e - Page 1054

Video Controller
19-20 MPC823e REFERENCE MANUAL MOTOROLA
VIDEO CONTROLLER
19
19.5.1 NTSC Example
The NTSC (National Television Standards Committee) broadcast method defines a virtual
screen of 525 lines, in which each line is 858 pixels long, but you can only see 485 of them.
Each horizontal line contains 720 pixels during the active line period and the rest of the line’s
pixels are presented during the digital blanking. Figure 19-5 illustrates how the frame is
divided into the following seven sections that correlate with the behavior of the FIELD and
BLANK
signals:
• Lines 1-3: frame 1 retrace blanking
• Lines 4-21: frame 0 blanking
• Lines 22-261: frame 0 active video for odd lines
• Lines 262-265: frame 0 retrace blanking
• Lines 266-284: frame 1 blanking
• Lines 285-524: frame 1 active video for even lines
• Line 525: frame 1 retrace blanking
Figure 19-5. Interlaced NTSC Format
BLANKING
LINE BLANK FIELD
101
301
4 0 0
21 0 0
22 0/1 0
261 0/1 0
262 0 0
265 0 0
266 0 1
284 0 1
285 0/1 1
524 0/1 1
525 0 1
BLANKING
ODD FIELD
EVEN FIELD
ACTIVE VIDEO
ACTIVE VIDEO
FIELD 1
FIELD 0
FIELD 1
CD EAB
CD EAB
RETRACE BLANKING
RETRACE BLANKING
RETRACE BLANKING
FRAM BUFFER A
FRAME BUFFER B