MB87P2020 Datasheet, PDF (168/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

MB87J2120, MB87P2020-A Hardware Manual
3.6 Scan Modes
Three scan modes are supported and determine the sequence pixel data that form the bit streams being out-
put. Figure 3-3 gives an illustration on geometrical reference points on the display used later to describe the
according bit streams.
4. Single Scan:
Pixels are written in one continuous stream, starting at upper left corner, proceeding left to right, line
by line.
5. Dual Scan:
Pixels are written in two parallel streams. The first stream starts at the upper left corner, proceeding
left to right, line by line. The second starts at the left margin of the line defined by DualScanOffset
(usually PY/2), proceeding left to write, line by line. Each stream contains DualScanOffset lines, i.e.
the stream for the upper display segment determines the number of lines
6. Zigzag Scan:
aka “Optrex-mode”. Pixels are written in one stream, starting at the upper left corner, proceeding
from left to right, however, line number sequence is peculiar: every other line number is biased with
DualScanOffset, i.e. the first line written is line #0, the second line is line number DualScanOffset,
the third line written is line #1, the fourth line written is line #(DualScanOffset+1) etc.
Table 3-6 shows the resulting bit streams according to the different scan modes. Please note that these
streams, as well as the reference points in figure 3-3 count in scan dots, which are not necessarily pixels
(this is determined by the bit stream format). A scan dot consists of all bits output during on display clock
cycle and may contain the bits of more than one pixel or even bits from fractions of adjacent pixels.
[0, 0]
[1, 0]
[PXScanDots−1, 0]
[PXScanDots−2, 0]
[1, 1]
[1, 0]
[0, DualScanOffs−1]
[1, DualScanOffs−1]
[PXScanDots−2, 1]
[PXScanDots−1, 1]
[PXScanDots−1, DualScanOffs−1]
[PXScanDots−2, DualScanOffs−1]
[1, DualScanOffs]
[0, DualScanOffs]
[0, PhysSizeY−1]
[1, PhysSizeY−1]
[PXScanDots−2, DualScanOffs]
[PXScanDots−1, DualScanOffs]
[PXScanDots−1, PhysSizeY−1]
[PXScanDots−2, PhysSizeY−1]
Figure 3-3: Geometric reference points on the display.
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