70592C Datasheet, PDF (30/314 Pages) Microchip Technology – High-Performance, 16-bit Microcontrollers

PIC24HJXXXGPX06A/X08A/X10A
3.3 CPU Control Registers
REGISTER 3-1: SR: CPU STATUS REGISTER
U-0
—
bit 15
U-0
U-0
U-0
—
—
—
R/W-0⁽¹⁾
R/W-0⁽²⁾
R/W-0⁽²⁾
R-0
IPL<2:0>⁽²⁾
RA
bit 7
U-0
—
R/W-0
N
U-0
—
R/W-0
OV
U-0
—
R/W-0
Z
R/W-0
DC
bit 8
R/W-0
C
bit 0
Legend:
C = Clear only bit
S = Set only bit
‘1’ = Bit is set
R = Readable bit
W = Writable bit
‘0’ = Bit is cleared
U = Unimplemented bit, read as ‘0’
-n = Value at POR
x = Bit is unknown
bit 15-9
bit 8
bit 7-5
bit 4
bit 3
bit 2
bit 1
bit 0
Unimplemented: Read as ‘0’
DC: MCU ALU Half Carry/Borrow bit
1 = A carry-out from the 4th low-order bit (for byte sized data) or 8th low-order bit (for word sized data)
of the result occurred
0 = No carry-out from the 4th low-order bit (for byte sized data) or 8th low-order bit (for word sized
data) of the result occurred
IPL<2:0>: CPU Interrupt Priority Level Status bits⁽²⁾
111 = CPU Interrupt Priority Level is 7 (15), user interrupts disabled
110 = CPU Interrupt Priority Level is 6 (14)
101 = CPU Interrupt Priority Level is 5 (13)
100 = CPU Interrupt Priority Level is 4 (12)
011 = CPU Interrupt Priority Level is 3 (11)
010 = CPU Interrupt Priority Level is 2 (10)
001 = CPU Interrupt Priority Level is 1 (9)
000 = CPU Interrupt Priority Level is 0 (8)
RA: REPEAT Loop Active bit
1 = REPEAT loop in progress
0 = REPEAT loop not in progress
N: MCU ALU Negative bit
1 = Result was negative
0 = Result was non-negative (zero or positive)
OV: MCU ALU Overflow bit
This bit is used for signed arithmetic (2’s complement). It indicates an overflow of the magnitude which
causes the sign bit to change state.
1 = Overflow occurred for signed arithmetic (in this arithmetic operation)
0 = No overflow occurred
Z: MCU ALU Zero bit
1 = An operation which affects the Z bit has set it at some time in the past
0 = The most recent operation which affects the Z bit has cleared it (i.e., a non-zero result)
C: MCU ALU Carry/Borrow bit
1 = A carry-out from the Most Significant bit (MSb) of the result occurred
0 = No carry-out from the Most Significant bit of the result occurred
Note 1:
2:
The IPL<2:0> bits are concatenated with the IPL<3> bit (CORCON<3>) to form the CPU Interrupt Priority
Level. The value in parentheses indicates the IPL if IPL<3> = 1. User interrupts are disabled when
IPL<3> = 1.
The IPL<2:0> Status bits are read only when NSTDIS = 1 (INTCON1<15>).
DS70592C-page 30
© 2011 Microchip Technology Inc.