SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 85

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

Stack Overflow Pointer STKOV
This non-bit addressable register is compared against the SP register after each
operation which pushes data onto the system stack (e.g. PUSH and CALL instructions
or interrupts) and after each subtraction from the SP register. If the content of the SP
register is less than the content of the STKOV register, a stack overflow hardware trap
will occur.
Because the least significant bit of register STKOV is tied to ‘0’ and bits 15 through 12
are tied to ‘1’ by hardware, the STKOV register can contain values from F000
only.
STKOV
Stack Overflow Reg.
Bit
stkov
The Stack Overflow Trap (entered when (SP) < (STKOV)) may be used in two different
ways:
• Fatal error indication treats the stack overflow as a system error through the
• Automatic system stack flushing allows to use the system stack as a ‘Stack Cache’
More details about the stack overflow trap service routine and virtual stack management
are given in
User’s Manual
15
1
r
associated trap service routine. Under these circumstances data in the bottom of the
stack may have been overwritten by the status information stacked upon servicing the
stack overflow trap.
for a bigger external user stack. In this case register STKOV should be initialized to a
value, which represents the desired lowest Top of Stack address plus 12 according to
the selected maximum stack size. This considers the worst case that will occur, when
a stack overflow condition is detected just during entry into an interrupt service routine.
Then, six additional stack word locations are required to push IP, PSW, and CSP for
both the interrupt service routine and the hardware trap service routine.
14
1
r
Chapter
13
1
r
Function
Modifiable portion of register STKOV
Specifies the lower limit of the internal system stack.
12
1
r
24.
11
10
SFR (FE14
9
8
4-28
7
H
/0A
stkov
H
rw
6
)
Central Processing Unit (CPU)
5
4
Reset Value: FA00
C164CM/C164SM
3
2
Derivatives
V1.0, 2002-02
H
to FFFE
1
0
0
H
H