18
XMEGA B [DATASHEET]
8291B–AVR–01/2013
3.14.9 SREG – Status Register
The status register (SREG) contains information about the result of the most recently executed arithmetic or logic
instruction.
Bit 7 – I: Global Interrupt Enable
The global interrupt enable bit must be set for interrupts to be enabled. If the global interrupt enable register is cleared,
none of the interrupts are enabled independent of the individual interrupt enable settings. This bit is not cleared by
hardware after an interrupt has occurred. This bit can be set and cleared by the application with the SEI and CLI
instructions, as described in “Instruction Set Description.” Changing the I flag through the I/O-register result in a one-
cycle wait state on the access.
Bit 6 – T: Bit Copy Storage
The bit copy instructions bit load (BLD) and bit store (BST) use the T bit as source or destination for the operated bit. A bit
from a register in the register file can be copied into this bit by the BST instruction, and this bit can be copied into a bit in
a register in the register file by the BLD instruction.
Bit 5 – H: Half Carry Flag
The half carry flag (H) indicates a half carry in some arithmetic operations. Half carry Is useful in BCD arithmetic. See
“Instruction Set Description” for detailed information.
Bit 4 – S: Sign Bit, S = N
V
The sign bit is always an exclusive or between the negative flag, N, and the two’s complement overflow flag, V. See
“Instruction Set Description” for detailed information.
Bit 3 – V: Two’s Complement Overflow Flag
The two’s complement overflow flag (V) supports two’s complement arithmetic. See “Instruction Set Description” for
detailed information.
Bit 2 – N: Negative Flag
The negative flag (N) indicates a negative result in an arithmetic or logic operation. See “Instruction Set Description” for
detailed information.
Bit 1 – Z: Zero Flag
The zero flag (Z) indicates a zero result in an arithmetic or logic operation. See “Instruction Set Description” for detailed
information.
Bit 0 – C: Carry Flag
The carry flag (C) indicates a carry in an arithmetic or logic operation. See “Instruction Set Description” for detailed
information.
Bit
7
6
5
4
3
2
1
0
I
T
H
S
V
N
Z
C
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Summary of Contents for XMEGA B
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Page 322: ...322 XMEGA B DATASHEET 8291B AVR 01 2013 Table 25 14 16 segments Character Table...
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