Datasheet

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ST7LITE20F2 ST7LITE25F2 ST7LITE29F2 Central processing unit
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pointed to by the SP. Then the other registers are stored in the next locations as shown in
Figure 11:
• When an interrupt is received, the SP is decremented and the context is pushed on the
stack.
• On return from interrupt, the SP is incremented and the context is popped from the
stack.
A subroutine call occupies two locations and an interrupt five locations in the stack area.
Figure 11. Stack manipulation example
PCH
PCL
SP
PCH
PCL
SP
PCL
PCH
X
A
CC
PCH
PCL
SP
PCL
PCH
X
A
CC
PCH
PCL
SP
PCL
PCH
X
A
CC
PCH
PCL
SP
SP
Y
CALL
Subroutine
Interrupt
Event
PUSH Y POP Y IRET
RET
or RSP
@ 01FFh
@ 0180h
Stack higher address = 01FFh
Stack lower address =
0180h