Motorola MPC823e - Page 1058

Video Controller
19-24 MPC823e REFERENCE MANUAL MOTOROLA
VIDEO CONTROLLER
19
19.5.2 PAL Example
The PAL (Phase Alternation Line) broadcast method defines a virtual screen of 625 lines,
which are 864 pixels long. However, you can only see 576 of these lines. Each horizontal
line contains 720 pixels during the active line period (which is visible to you) with the rest of
the line’s pixels presented during digital blanking. Figure 19-7 illustrates how the frame is
divided into six sections that correlate with the behavior of the FIELD and BLANK
signals:
• Lines 1-22: Frame 0 blanking
• Lines 23-310: Frame 0 active video for odd lines
• Lines 311-312: Frame 0 for retrace blanking
• Lines 313-335: Frame 1 blanking
• Lines 336-623: Frame 1 active video for even lines
• Lines 624-625: Frame 1 retrace blanking
Figure 19-7. Interlaced PAL Format
LINE BLANK FIELD
1 0 0
22 0 0
23 0/1 0
310 0/1 0
311 0 0
312 0 0
313 0 1
335 0 1
336 0/1 1
623 0/1 1
624 0 1
625 0 1
BLANKING
BLANKING
ODD FIELD
EVEN FIELD
ACTIVE VIDEO
ACTIVE VIDEO
FIELD 0
FIELD 1
C
DE
AB
CD EAB
RETRACE BLANKING
RETRACE BLANKING
FRAME BUFFER A
FRAME BUFFER B