m37905 Renesas Electronics Corporation., m37905 Datasheet - Page 103

• Manufacturer Part Number: m37905
• Description: Mitsubishi 16-bit Single-chip Microcomputer 7700 Family / 7900 Series
• Manufacturer: Renesas Electronics Corporation.

INTERRUPTS
[Precautions for interrupts]
[Precautions for interrupts]
1. In order to change the interrupt priority level select bits (bits 0 to 2 at addresses 6E
Fig. 6.10.6 Program example to reserve time required for change of interrupt priority level
Table 6.10.2 Correspondence between number of instructions to be inserted in Figure 6.10.6 and
6-22
Note: We recommend [b5 = “1”, b4 = “0”].
2. When using pin P4OUT
3. When using pin P6OUT
Interrupt priority detection time select bits (Note)
F5
change of the interrupt priority level. Therefore, when the interrupt priority level of a certain interrupt
source is repeatedly changed in a very short time, which consists of a few instructions, it is necessary
to reserve the time required for the change by software. Figure 6.10.6 shows a program example to
reserve the time required for the change. Note that the time required for the change depends on the
contents of the interrupt priority detection time select bits (bits 4 and 5 at address 5E
the correspondence between the number of instructions inserted in Figure 6.10.6 and the interrupt priority
detection time select bits.
P4
P6
16
0
0
to P4
to P6
to F9
b5
Note: Except a write instruction for address XX
0
0
1
1
:
MOVMB 00XXH, #0XH
NOP
NOP
NOP
MOVMB 00XXH, #0XH
:
7
7
XX: any of 6E to 7F, F1, F2, F5 to F9, and FD to FF
16
in the input mode. (Refer to section “5.2.3 Pin P4OUT
in the input mode. (Refer to section “5.2.4 Pin P6OUT
, FD
interrupt priority detection time select bits
cycles as the NOP instruction can also be inserted, instead of the NOP instruction.
For the number of inserted NOP instructions, see Table 6.10.2.
16
to FF
CUT
CUT
16
), 2 to 7 cycles of f
/INT
/INT
0
4
as an input pin of an external interrupt (pin INT
as an input pin of an external interrupt (pin INT
b4
; Write instruction for the interrupt priority level select bits
; Inserted NOP instruction (Note)
;
;
; Write instruction for the interrupt priority level select bits
0
1
0
1
7905 Group User’s Manual Rev.1.0
sys
7 cycles of f
4 cycles of f
2 cycles of f
Do not select.
are required after execution of a write instruction until
Interrupt priority level
16
detection time
, any instruction which has the same
sys
sys
sys
CUT
CUT
/INT
/INT
0
4
.”)
.”)
0
4
), be sure to use port pins
), be sure to use port pins
Number of inserted
NOP instructions
16
16
7 or more
4 or more
2 or more
). Table 6.10.2 lists
to 7F
16
, F1
16
, F2
16
,