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3.3.6
Interrupt Response Time
Table 3.4 shows the number of wait states after an interrupt request flag is set until the first
instruction of the interrupt handler is executed.
Table 3.4
Interrupt Wait States
Item
Waiting time for completion of executing instruction*
Saving of PC and CCR to stack
Vector fetch
Instruction fetch
Internal processing
Total
Note:
*
Not including EEPMOV instruction.
3.4
Application Notes
3.4.1
Notes on Stack Area Use
When word data is accessed in the H8/3857 Group, the least significant bit of the address is
regarded as 0. Access to the stack always takes place in word size, so the stack pointer (SP: R7)
should never indicate an odd address. Use PUSH Rn (MOV.W Rn, @–SP) or POP Rn (MOV.W
@SP+, Rn) to save or restore register values.
Setting an odd address in SP may cause a program to crash. An example is shown in figure 3.6.
3. Exception Handling
States
1 to 13
4
2
4
4
15 to 27
Rev.3.00 Jul. 19, 2007 page 89 of 532
REJ09B0397-0300
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