PIC24FJ64GA104 FAMILY
3.2
CPU Control Registers
REGISTER 3-1:
SR: ALU STATUS REGISTER
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
U-0
—
R/W-0
DC
bit 15
bit 8
R/W-0(1)
IPL2(2)
bit 7
R/W-0(1)
IPL1(2)
R/W-0(1)
IPL0(2)
R-0
RA
R/W-0
N
R/W-0
OV
R/W-0
Z
R/W-0
C
bit 0
Legend:
R = Readable bit
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
-n = Value at POR
bit 15-9
bit 8
Unimplemented: Read as ‘0’
DC: 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 or 8th low-order bit of the result has occurred
bit 7-5
IPL<2:0>: CPU Interrupt Priority Level Status bits(1,2)
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)
bit 4
bit 3
bit 2
bit 1
bit 0
RA: REPEATLoop Active bit
1= REPEATloop in progress
0= REPEATloop not in progress
N: ALU Negative bit
1= Result was negative
0= Result was non-negative (zero or positive)
OV: ALU Overflow bit
1= Overflow occurred for signed (2’s complement) arithmetic in this arithmetic operation
0= No overflow has occurred
Z: ALU Zero bit
1= An operation which effects the Z bit has set it at some time in the past
0= The most recent operation which effects the Z bit has cleared it (i.e., a non-zero result)
C: ALU Carry/Borrow bit
1= A carry out from the Most Significant bit of the result occurred
0= No carry out from the Most Significant bit of the result occurred
Note 1: The IPL Status bits are read-only when NSTDIS (INTCON1<15>) = 1.
2: The IPL Status bits are concatenated with the IPL3 bit (CORCON<3>) to form the CPU Interrupt Priority
Level (IPL). The value in parentheses indicates the IPL when IPL3 = 1.
DS39951C-page 28
2010 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
