M30280F6HP RENESAS [Renesas Technology Corp], M30280F6HP Datasheet - Page 98

• Manufacturer Part Number: M30280F6HP
• Description: 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/Tiny SERIES
• Manufacturer: RENESAS [Renesas Technology Corp]

M
R
R
e
E
1
. v
Figure 9.7 Stack Status Before and After Acceptance of Interrupt Request
J
6
0
9.4.3 Saving Registers
C
2
9
2 /
In the interrupt sequence, the FLG register and PC are saved to the stack.
At this time, the 4 high-order bits of the PC and the 4 high-order (IPL) and 8 low-order bits of the FLG
register, 16 bits in total, are saved to the stack first. Next, the 16 low-order bits of the PC are saved.
Figure 9.7 shows the stack status before and after an interrupt request is accepted.
The other necessary registers must be saved in a program at the beginning of the interrupt routine. Use
the PUSHM instruction, and all registers except SP can be saved with a single instruction.
0 .
B
Address
0
0
8
0
m – 4
m – 3
m – 2
m – 1
m + 1
Stack status before interrupt request
is acknowledged
m
G
4
J
7
a
o r
MSB
0 -
. n
u
2
3
p
0
, 1
Content of previous stack
Content of previous stack
0
(
M
2
0
1
0
6
7
C
Stack
2 /
, 8
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M
1
6
C
2 /
f o
LSB
8
3
) B
8
5
[SP]
SP value before
interrupt request is
accepted.
Address
m – 4
m – 3
m – 2
m – 1
m
m + 1
Stack status after interrupt request
is acknowledged
MSB
Content of previous stack
Content of previous stack
FLG
H
Stack
PC
PC
FLG
M
L
L
PC
H
LSB
[SP]
New SP value
9. Interrupts