70291E Datasheet, PDF (29/436 Pages) Microchip Technology – High-Performance, 16-bit Digital Signal Controllers

dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04 AND dsPIC33FJ128MCX02/X04
3.5 CPU Control Registers
REGISTER 3-1: SR: CPU STATUS REGISTER
R-0
OA
bit 15
R-0
R/C-0
R/C-0
OB
SA⁽¹⁾
SB⁽¹⁾
R/W-0⁽³⁾
R/W-0⁽³⁾
R/W-0⁽³⁾
R-0
IPL<2:0>⁽²⁾
RA
bit 7
R-0
OAB
R/W-0
N
R/C-0
SAB
R/W-0
OV
R -0
DA
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
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
OA: Accumulator A Overflow Status bit
1 = Accumulator A overflowed
0 = Accumulator A has not overflowed
OB: Accumulator B Overflow Status bit
1 = Accumulator B overflowed
0 = Accumulator B has not overflowed
SA: Accumulator A Saturation ‘Sticky’ Status bit⁽¹⁾
1 = Accumulator A is saturated or has been saturated at some time
0 = Accumulator A is not saturated
SB: Accumulator B Saturation ‘Sticky’ Status bit⁽¹⁾
1 = Accumulator B is saturated or has been saturated at some time
0 = Accumulator B is not saturated
OAB: OA || OB Combined Accumulator Overflow Status bit
1 = Accumulators A or B have overflowed
0 = Neither Accumulators A or B have overflowed
SAB: SA || SB Combined Accumulator (Sticky) Status bit⁽⁴⁾
1 = Accumulators A or B are saturated or have been saturated at some time in the past
0 = Neither Accumulator A or B are saturated
DA: DO Loop Active bit
1 = DO loop in progress
0 = DO loop not in progress
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
Note 1:
2:
3:
4:
This bit can be read or cleared (not set).
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 the NSTDIS bit (INTCON1<15>) = 1.
This bit can be read or cleared (not set). Clearing this bit clears SA and SB.
© 2011 Microchip Technology Inc.
DS70291E-page 29