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APPLICATION
5.1 Example of multi-line display
(2) V
interrupt processing routine
SYNC
The V
interrupt processing routine consists of; multi-line display start processing and multi-line
SYNC
display correction processing. The correction processing corrects erroneous multi-line display due to
various influences.
T
D
V_ICON1
V_ICON2
Setting for
ICON1 (address 00FE
multiple
ICON2 (address 00FF
interrupts
I
Push registers X, Y, A
Pass this
process only
once at
display start.
Setting for
multiple
interrupts
Fig. 5.1.4 Flowchart of V
5-4
ICON1, ICON2:
Interrupt control registers 1, 2
CRTE :
Bit 4 of interrupt control register 1
<CRT interrupt enable bit>
CRTR :
Bit 4 of interrupt request register 1
<CRT interrupt request bit>
V
interrupt processing routine
SYNC
←"0"
←"0"
←ICON1
←ICON2
←"00000001
)
16
←"00000000
)
16
←"0"
F_VSYNC
=1
F_VSYNC
CRTR (bit 4 at address 00FE
16
CRTE (bit 4 at address 00FC
16
CC (address 00EA
)
16
C
Correction for
erroneous
multi-line display
(Refer to "5.1.6")
Pop registers X, Y, A
←"1"
I
←V_ICON1
ICON1
←V_ICON2
ICON2
RETURN
interrupt processing routine
SYNC
7220 Group User's Manual
V_ICON1, V_ICON2 :
←Push ICON1 contents during V
←Push ICON2 contents during V
←Enable only Timer 1 interrupt
"
2
"
2
←Enable multipule interrupt set by steps
(Refer to "5.1.7 (2)")
=0
←"0"
←"0"
)
←"1"
←Enable CRT interrupt
)
←"07
←All blocks display on
"
16
Line counter←"2"
CV1←Vertical display start position of the 1st line (block 1)
CV2←Vertical display start position of the 2nd line (block 2)
CRTR (bit 4 at address 00FE
←Disable all interrupts
←Pop ICON 1 and 2 contents during
interrupt (Refer to "5.1.7 (2)")
V
SYNC
Note: The multiple interrupt priority of this system
interrupt is as below.
Timer 1 > V
CC :
CRT control register
Line counter :
Counter RAM for line counting
F_VSYNC :
V
flag
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CV1,CV2 :
Vertical position registers 1, 2
Back up RAM for interrupt control
registers 1, 2 during V
A :
Accumulator
X :
Index register X
Y :
Index register Y
T :
X modified operation mode flag
D :
Decimal operation mode flag
interrupt
SYNC
interrupt
SYNC
,
)←"0"
16
> CRT
SYNC
interrupt
SYNC
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