3822_03 Datasheet, PDF (81/328 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.2 Interrupts
2.2 Interrupts
2.2.1 Explanation of operations
When an interrupt request is accepted, the contents immediately before acceptance of the interrupt re-
quests of the following registers is automatically pushed onto the stack area in the order of Œ,  and Ž.
ŒHigh-order (PCH) contents of program counter
Low-order (PCL) contents of program counter
ŽContents of processor status register (PS)
After the contents of the above registers are pushed onto the stack area, the accepted interrupt vector
address enters the program counter and consequently the interrupt processing routine is executed.
When the RTI instruction is executed at the end of the interrupt processing routine, the contents of the
above registers pushed onto the stack area are restored to the respective registers in the order of Ž, 
and Πand the processing executed immediately before acceptance of the interrupts is continued.
Figure 2.2.1 shows an interrupt operation diagram.
Executing routine
·······
Interrupt occurs
(Accepting interrupt request)
Suspended
operation
Resume processing
·······
Contents of program counter (high-order) are pushed onto stack
Contents of program counter (low-order) are pushed onto stack
Contents of processor status register are pushed onto stack
Interrupt
processing
routine
RTI instruction
Contents of processor status register are poped from stack
Contents of program counter (low-order) are poped from stack
Contents of program counter (high-order) are poped from stack
Fig. 2.2.1 Interrupt operation diagram
: Operation commanded by software
: Internal operation to be performed automatically
3822 GROUP USER’S MANUAL
2–15