
SCG0
GIE
Z
C
rw-0
15
0
Reserved
N
CPU
OFF
OSC
OFF
SCG1
V
8
7
9
CPU Registers
4.3.3 Status Register (SR)
The 16-bit Status Register (SR, also called R2), used as a source or destination register, can only be used
in register mode addressed with word instructions. The remaining combinations of addressing modes are
used to support the constant generator.
shows the SR bits. Do not write 20-bit values to the
SR. Unpredictable operation can result.
Figure 4-9. SR Bits
describes the SR bits.
Table 4-1. SR Bit Description
Bit
Description
Reserved
Reserved
V
Overflow. This bit is set when the result of an arithmetic operation overflows the signed-variable range.
Set when:
ADD(.B), ADDX(.B,.A),
po positive = negative
ADDC(.B), ADDCX(.B.A),
ne negative = positive
ADDA
otherwise reset
Set when:
SUB(.B), SUBX(.B,.A),
positive – negative = negative
SUBC(.B),SUBCX(.B,.A),
negative – positive = positive
SUBA, CMP(.B),
otherwise reset
CMPX(.B,.A), CMPA
SCG1
System clock generator 1. This bit may be used to enable or disable functions in the clock system depending on the
device family; for example, DCO bias enable or disable.
SCG0
System clock generator 0. This bit may be used to enable or disable functions in the clock system depending on the
device family; for example, FLL enable or disable.
OSCOFF
Oscillator off. This bit, when set, turns off the LFXT1 crystal oscillator when LFXT1CLK is not used for MCLK or
SMCLK.
CPUOFF
CPU off. This bit, when set, turns off the CPU.
SCG1
The bits CPUOFF, OSCOFF, SCG0 and SCG1 request the system to enter a low-power mode
SCG0
OSCOFF
CPUOFF
GIE
General interrupt enable. This bit, when set, enables maskable interrupts. When reset, all maskable interrupts are
disabled.
N
Negative. This bit is set when the result of an operation is negative and cleared when the result is positive.
Z
Zero. This bit is set when the result of an operation is 0 and cleared when the result is not 0.
C
Carry. This bit is set when the result of an operation produced a carry and cleared when no carry occurred.
NOTE:
Bit manipulations of the SR should be done by the following instructions: MOV, BIS, and
BIC.
93
SLAU272C – May 2011 – Revised November 2013
CPUX
Copyright © 2011–2013, Texas Instruments Incorporated