PIC18FXX8 Datasheet, PDF (41/402 Pages) Microchip Technology – 28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

PIC18FXX8
REGISTER 4-1:
STKPTR: STACK POINTER REGISTER
R/C-0
R/C-0
U-0
R/W-0
STKFUL STKUNF
—
SP4
bit 7
R/W-0
SP3
R/W-0
SP2
R/W-0
SP1
R/W-0
SP0
bit 0
bit 7 STKFUL: Stack Full Flag bit
1 = Stack became full or overflowed
0 = Stack has not become full or overflowed
bit 6 STKUNF: Stack Underflow Flag bit
1 = Stack underflow occurred
0 = Stack underflow did not occur
bit 5 Unimplemented: Read as ‘0’
bit 4-0 SP4:SP0: Stack Pointer Location bits
Note: Bit 7 and bit 6 need to be cleared following a stack underflow or a stack overflow.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared C = Clearable bit
FIGURE 4-3:
RETURN ADDRESS STACK AND ASSOCIATED REGISTERS
TOSU
00h
TOSH
1Ah
Return Address Stack
TOSL
34h
11111
11110
11101
STKPTR<4:0>
00010
Top-of-Stack 001A34h
000D58h
000000h
00011
00010
00001
00000⁽¹⁾
Note 1: No RAM associated with this address; always maintained ‘0’s.
 2004 Microchip Technology Inc.
DS41159D-page 39