7220 Datasheet, PDF (180/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
5.1 Example of multi-line display
5.1.5 Line counter
The line counter determines which line of display data is to be set. For example, if a CRT interrupt occurs
at the end of the first line display, the line counter value will be “2.” Therefore, the 3rd line display data
must be set from the end of the 1st line display to the start of the 3rd line display. Then, the line counter
value is incremented and becomes “3.”
Figure 5.1.7 shows the example of the setup timing for the line counter and the display character data.
Line counter value
2
3
4
Start of the
3rd line display
0
1
The 1st line (block 1)
The 2nd line (block 2)
The 3rd line (block 1)
The 4th line (block 2)
The 11th line (block 1)
The 12th line (block 2)
End of the
1st line display
CRT interrupt
Line counter value : 2
Set 3rd line display data
by the start of 3rd line
display
↓
Line counter value: 3
A
Fig. 5.1.7 Example of setup timing for line counter and display character data
7220 Group User’s Manual
5-7