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CHAPTER 6 INTERRUPTS
MB90560 series
I
Hardware interrupt suppression
Acceptance of hardware interrupt requests is suppressed under the following conditions.
G
Hardware interrupt suppression during writing to the peripheral function control register
area
When data is being written to the peripheral function control register area, hardware interrupt
requests are not accepted. This prevents the CPU from making operational mistakes. The
mistakes may be caused if an interrupt request is generated during data is being written to the
interrupt control registers for a resource. The peripheral function control register area is not the I/
O addressing area at “000000
H
“ to “0000FF
H
”, but the area allocated to the control register of the
peripheral function control register and data register.
Figure 6.4-1 shows hardware interrupt operation during writing to the built-in peripheral area
Figure 6.4-1 Hardware interrupt request while writing to the peripheral function
control register area
G
Hardware interrupt suppression by interrupt suppression instruction
The ten types of hardware interrupt suppression instructions listed in Table 6.4-2 ignore interrupt
requests without detecting whether a hardware interrupt request exists.
Table 6.4-2 Hardware interrupt suppression instruction
Even if a valid hardware interrupt request is generated during execution of one of these
instructions, the interrupt is not processed until the first time an instruction of a different type is
executed.
G
Hardware interrupt suppression during execution of software interrupt
When a software interrupt is activated, the I flag is cleared to “0”. In this state, other interrupt
requests cannot be accepted.
Prefix code
Interrupts/hold suppression
instructions (instructions that delay
the effect of the prefix code)
Instructions that do not
accept interrupts and hold
requests
PCB
DTB
ADB
SPB
CMR
NCC
MOV
OR
AND
POPW PS
ILM, #imm8
CCR, #imm8
CCR, #imm8
MOV A, #08
MOV io,A
MOV A,2000H
Interrupt processing
. . . . .
Instruction that writes to the peripheral function control register area
An interrupt request
is generated here
Does not branch
to the interrupt
Branches to
the interrupt