CPU Registers
4-9
16-Bit MSP430X CPU
4.3.3
Status Register (SR)
The 16-bit status register (SR/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. Figure 4−9 shows the SR bits. Do not write 20-bit values
to the SR. Unpredictable operation can result.
Figure 4−9. Status Register Bits
SCG0
GIE
Z
C
rw-0
15
0
Reserved
N
CPU
OFF
OSC
OFF
SCG1
V
8
7
9
Table 4−1 describes the status register bits.
Table 4−1. Description of Status Register Bits
Bit
Description
Reserved
Reserved
V
Overflow bit. This bit is set when the result of an arithmetic operation
overflows the signed-variable range.
ADD(.B), ADDX(.B,.A),
ADDC(.B), ADDCX(.B.A),
ADDA
Set when:
po positive = negative
ne negative = positive
otherwise reset
SUB(.B), SUBX(.B,.A),
SUBC(.B),SUBCX(.B,.A),
SUBA, CMP(.B),
CMPX(.B,.A), CMPA
Set when:
positive − negative = negative
negative − positive = positive
otherwise reset
SCG1
System clock generator 1. This bit, when set, turns off the DCO dc
generator if DCOCLK is not used for MCLK or SMCLK.
SCG0
System clock generator 0. This bit, when set, turns off the FLL+ loop
control.
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.
GIE
General interrupt enable. This bit, when set, enables maskable inter-
rupts. When reset, all maskable interrupts are disabled.
N
Negative bit. This bit is set when the result of an operation is negative
and cleared when the result is positive.
Содержание MSP430x4xx Family
Страница 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
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Страница 304: ...5 20 FLL Clock Module ...
Страница 340: ...7 8 Supply Voltage Supervisor ...
Страница 348: ...8 8 16 Bit Hardware Multiplier ...
Страница 372: ...9 24 32 Bit Hardware Multiplier ...
Страница 400: ...10 28 DMA Controller ...
Страница 428: ...13 10 Basic Timer1 ...
Страница 466: ...15 24 Timer_A ...
Страница 522: ...17 30 USART Peripheral Interface UART Mode ...
Страница 544: ...18 22 USART Peripheral Interface SPI Mode ...
Страница 672: ...23 12 Comparator_A ...
Страница 692: ...24 20 LCD Controller ...
Страница 746: ...26 28 ADC12 ...