7220 Datasheet, PDF (98/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

FUNCTIONAL DESCRIPTION
2.11 CRT display function
2.11 CRT display function
Table 2.11.1 shows the outline the CRT display function of the M37221M6-XXXSP/FP.
M37220M3-XXXSP/FP
Refer to “CHAPTER 4. M37220M3-XXXSP/FP.”
The M37221M6-XXXSP/FP has the 24 characters ! 2 lines CRT display circuit. CRT display is controlled
by the CRT control register.
Up to 256 kinds of characters can be displayed, and colors can be specified for each character. Up to 4
kinds of colors can be displayed on 1 screen. A combination of up to 7 colors can be obtained by using each
output signal (R, G, and B). Characters are displayed in a 12 ! 16 dot structure to display smooth character
patterns (refer to “Figure 2.11.1”).
How to display characters on the CRT screen is described below.
ΠWrite the display character code in the display RAM.
 Specify the display color by the color register.
Ž Write the color register in which the display color is set in the display RAM.
 Specify the vertical position by the vertical position register.
 Specify the character size by the character size register.
‘ Specify the horizontal position by the horizontal position register.
’ Write the display control bit to the designated block display flag of the CRT control register. When this
is done, the CRT starts according to the input of the VSYNC signal.
The CRT display circuit has an extended display mode. This mode allows multi-line (more than 3 lines) to
be displayed on the screen by interrupting each time 1 line is displayed and rewriting data in the block which
display is terminated by software.
Figure 2.11.2 shows the CRT display circuit block diagram. Figure 2.11.3 shows the CRT control register.
12 dots
16 dots
Table 2.11.1 Outline of CRT display function
Parameter
Performance
Number of display
24 characters ! 2 lines
character
Dot structure
12 dots ! 16 dots
(Refer to “Figure 2.11.1”)
Kinds of character
256 kinds
Kinds of character sizes 3 kinds
Color ^{Kind of colors 1 screen; 4 kinds, maximum 7 kinds}
Coloring unit A character
Display extension
Possible (multi-line display)
Raster coloring
Possible (maximum 7 kinds)
Character background _{Possible (a character unit, 1}
coloring
screen; 4 kinds, maximum 7 kinds)
Fig. 2.11.1 Structure of CRT display character
7220 Group User’s Manual
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