SONIX SN8P27142_2715, User Manual

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SN8P2714X_2715
8-bit micro-controller build-in 12-bit ADC
SONiX TECHNOLOGY CO., LTD
Page 29
V1.4
3.6.2 STACK REGISTERS
The stack pointer (STKP) is a 4-bit register to store the address used to access the stack buffer, 11-bits 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 (Stack-Save) and reading (Stack-Restore) from the top of
stack. Stack-Save operation decrements the STKP and the Stack-Resotre operation increments one time. That makes
the STKP always points to the top address of stack buffer and writes 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.
STKP (stack pointer) initial value = 0xxx x111
0DFH Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
STKP GIE - - - - STKPB2 STKPB1 STKPB0
R/W - - - - R/W R/W R/W
STKPBn: Stack pointer. (n = 0 ~ 3)
GIE: Global interrupt control bit. 0 = disable, 1 = enable. More detail information is in interrupt chapter.
 Example: Stack pointer (STKP) reset routine.
MOV
A, #00000111B
B0MOV STKP, A
STKn (stack buffer) initial value = xxxx xxxx xxxx xxxx, STKn = STKnH + STKnL (n = 7 ~ 0)
0F0H~0FFH Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
STKnH - - - - - SnPC10 SnPC9 SnPC8
- - - - - R/W R/W R/W
0F0H~0FFH Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
STKnL SnPC7 SnPC6 SnPC5 SnPC4 SnPC3 SnPC2 SnPC1 SnPC0
R/W R/W R/W R/W R/W R/W R/W R/W
STKnH: Store PCH data as interrupt or call executing. The n expressed 0 ~7.
STKnL: Store PCL data as interrupt or call executing. The n expressed 0 ~7.