7220 datasheet(183/303 Pages) RENESAS

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APPLICATION

5.1 Example of multi-line display

7220 Group User’s Manual

5-10

(2)

When setting multiple interrupts

Various priority processings are executed by enabling multiple interrupts and by setting priorities by

software. For example, to set the priority listed below;

Timer 1 interrupt

VSYNC interrupt

CRT interrupt

execute the following process:

Set only interrupt enable bits (ICON1, ICON2) whose priorities are higher than the current interrupt,

and enable the interrupt disable flag (I) in only the current interrupt processing routine.

Figure 5.1.9 shows the timing when all interrupt request bits (CRT, VSYNC, Timer 1) are “1” at the

same sampling point.

Note: When setting multiple interrupts, be sure to determine priority levels to prevent occurrence of

plural interrupts with the same priority level.

Fig. 5.1.9 Timing when all interrupt request bits are “1” at the same sampling point

CRT interrupt request bit

VSYNC interrupt request bit

Timer 1 interrupt request bit

CRT interrupt processing

VSYNC interrupt processing

Timer 1 interrupt processing

Interrupt disable flag (I)

1’

A’

(series of

)

B’

(series of

)

(series of

)

7220 Datasheet(PDF) 183 Page - Renesas Technology Corp