MC68HC05K1 FREESCALE [Freescale Semiconductor, Inc], MC68HC05K1 Datasheet - Page 38

• Manufacturer Part Number: MC68HC05K1
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Technical Data
3.3.3 Stack Pointer
Technical Data
Reset:
Read:
Write:
Bit 15
0
0
14
0
0
13
0
0
The stack pointer (SP) shown in
contains the address of the next location on the stack. During a reset or
after the reset stack pointer (RSP) instruction, the stack pointer initializes
to $00FF. The address in the stack pointer decrements as data is
pushed onto the stack and increments as data is pulled from the stack.
The 11 most significant bits of the stack pointer are permanently fixed at
00000000111, so the stack pointer produces addresses from $00FF to
$00E0. If subroutines and interrupts use more than 32 stack locations,
the stack pointer wraps around to address $00FF and begins writing
over the previously stored data. A subroutine call uses two stack
locations; an interrupt uses five locations.
12
0
0
Freescale Semiconductor, Inc.
For More Information On This Product,
11
0
0
Figure 3-4. Stack Pointer (SP)
Central Processor Unit (CPU)
10
0
0
Go to: www.freescale.com
9
0
0
8
0
0
7
1
1
Figure 3-4
6
1
1
MC68HC05K0 • MC68HC05K1 — Rev. 2.0
5
1
1
is a 16-bit register that
4
1
3
1
2
1
1
1
Bit 0
1