SN8P1600
8-bit micro-controller
SONiX TECHNOLOGY CO., LTD
Page 30
Revision 1.94
STACK REGISTERS
The stack pointer (STKP) is a 3-bit register to store the address used to access the stack buffer, 10-bit data memory
(STKnH and STKnL) set aside for temporary storage of stack addresses.
The two stack operations are writing to the top of the stack and reading from the top of stack. Push operation
decrements the STKP and the pop operation increments each time. That makes the STKP always point to the top
address of stack buffer and write the last program counter value (PC) into the stack buffer.
The program counter (PC) value is stored in the stack buffer before a CALL instruction executed or during interrupt
service routine. Stack operation is a LIFO type (Last in and first out). The stack pointer (STKP) and stack buffer
(STKnH and STKnL) are located in the system register area bank 0.
0DFH
Bit 7
Bit 6
Bit 5
Bit 4
STKP
GIE
-
-
-
Read/Write
R/W
-
-
-
After reset
0
-
-
-
STKPBn: Stack pointer. (n = 0 ~ 2)
GIE: Global interrupt control bit. 0 = disable, 1 = enable. There is more on this in interrupt chapter.
Example: Stack pointer (STKP) reset routine.
MOV
A, #00000111B
B0MOV
STKP, A
STKn = <STKnH , STKnL> (n = 3 ~ 0)
SN8P1602/1603
0F0H~0FFH
Bit 7
Bit 6
Bit 5
Bit 4
STKnH
-
-
-
-
Read/Write
-
-
-
-
After reset
-
-
-
-
SN8P1604
0F0H~0FFH
Bit 7
Bit 6
Bit 5
Bit 4
STKnH
-
-
-
-
Read/Write
-
-
-
-
After reset
-
-
-
-
SN8P1602/1603/1604
0F0H~0FFH
Bit 7
Bit 6
Bit 5
Bit 4
STKnL
SnPC7
SnPC6
SnPC5
SnPC4
Read/Write
R/W
R/W
R/W
R/W
After reset
0
0
0
0
STKnH: Store PCH data as interrupt or call executing. The n expressed 0 ~3.
STKnL: Store PCL data as interrupt or call executing. The n expressed 0 ~3.
Bit 3
-
-
-
Bit 2
STKPB2
R/W
1
Bit 1
STKPB1
R/W
1
Bit 0
STKPB0
R/W
1
Bit 3
-
-
-
Bit 2
-
-
-
Bit 1
SnPC9
R/W
0
Bit 0
SnPC8
R/W
0
Bit 3
SnPC11
R/W
0
Bit 2
SnPC10
R/W
0
Bit 1
SnPC9
R/W
0
Bit 0
SnPC8
R/W
0
Bit 3
SnPC3
R/W
0
Bit 2
SnPC2
R/W
0
Bit 1
SnPC1
R/W
0
Bit 0
SnPC0
R/W
0