HD6432633 Datasheet, PDF (202/1453 Pages) Renesas Technology Corp – Series of Microcomputers (MCUs: microcomputer units)

Table 5-10 Number of States in Interrupt Handling Routine Execution Statuses
Object of Access
External Device
8 Bit Bus
16 Bit Bus
Symbol
Internal 2-State
Memory Access
3-State
Access
2-State
Access
3-State
Access
Instruction fetch
S_I 1
4
6+2m
2
Branch address read
S_J
Stack manipulation
S_K
Legend
m : Number of wait states in an external device access.
3+m
5.5 Usage Notes
5.5.1 Contention between Interrupt Generation and Disabling
When an interrupt enable bit is cleared to 0 to disable interrupts, the disabling becomes effective
after execution of the instruction.
In other words, when an interrupt enable bit is cleared to 0 by an instruction such as BCLR or
MOV, if an interrupt is generated during execution of the instruction, the interrupt concerned will
still be enabled on completion of the instruction, and so interrupt exception handling for that
interrupt will be executed on completion of the instruction. However, if there is an interrupt
request of higher priority than that interrupt, interrupt exception handling will be executed for the
higher-priority interrupt, and the lower-priority interrupt will be ignored.
The same also applies when an interrupt source flag is cleared to 0.
Figure 5-8 shows an example in which the CMIEA bit in the TMR’s TCR register is cleared to 0.
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