7220 datasheet(184/303 Pages) RENESAS

184 / 303 page

APPLICATION

5.1 Example of multi-line display

5-11

7220 Group User’s Manual

(3) CRT interrupt processing routine when setting multiple interrupts

Figure 5.1.10 shows the flowchart of CRT interrupt processing routine when setting multiple interrupts.

A and B are the setting routines for multiple interrupts.

Fig. 5.1.10 Flowchart of CRT interrupt processing routine (when setting multiple interrupts)

CRT interrupt processing routine

RETURN

CRT interrupt processing

ICON1

ICON2

←ICON1

←ICON2

←“001000012”

←“000000002”

←“0”

CRT_ICON1

CRT_ICON2

ICON1 (address 00FE 16)

ICON2 (address 00FF 16)

Push registers X, Y, A

ICON1, ICON2:

CRT_ICON1, CRT_ICON2 :

A :

X :

Y :

T :

D :

Interrupt control registers 1, 2

Back up RAM for interrupt control

registers 1, 2 during CRT interrupt

Accumulator

Index register X

Index register Y

X modified operation mode flag

Decimal operation mode flag

←Disable all interrupts

←“1”

←CRT_ICON1

←CRT_ICON2

←“0”

Set routine for

multiple

interrupts

Pop the registers X, Y, A

Disable

multiple interrupts

←Enable VSYNC and Timer 1 interrupts to

take priority than CRT interrupt.

And also, be sure to disable the following interrupts:

-CRT interrupt

-all interrupts with lower priority than CRT

interrupt.

←Pop ICON 1 and 2 contents

during CRT interrupt

Enable state of

multiple interrupts

(VSYNC, Timer 1)

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