
3-6
MCF5249UM
MOTOROLA
Processor Register Description
3.2.3.1 STATUS REGISTER (SR)
The SR stores the processor status and includes the CCR, the interrupt priority mask, and other control
bits. In the supervisor mode, software can access the entire SR. In user mode, only the lower 8 bits are
accessible (CCR). The control bits indicate the following states for the processor: trace mode (T-bit),
supervisor or user mode (S bit), and master or interrupt state (M).
3.2.3.2 VECTOR BASE REGISTER (VBR)
The VBR contains the base address of the exception vector table in memory. The displacement of an
exception vector is added to the value in this register to access the vector table. The lower 20 bits of the
VBR are not implemented by ColdFire processors; they are zero, forcing the table to be aligned on a 1
MByte boundary.
Table 3-4 Status Register
SYSTEM BYTE
CONDITION CODE REGISTER (CCR)
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
T
0
S
M
0
I[2:0]
0
X
N
Z
V
C
Table 3-5 Status Bit Descriptions
BIT NAME
DESCRIPTION
T
When set, the trace enable allows the processor to perform a trace exception after every
instruction.
S
The supervisor / user state bit denotes whether the processor is in supervisor mode
(S=1) or user mode (S=0).
M
The master / interrupt state bit is cleared by an interrupt exception, and can be set by
software during execution of the RTE or move to SR instructions.
I [2:0]
The interrupt priority mask defines the current interrupt priority. Interrupt requests are
inhibited for all priority levels less than or equal to the current priority, except the
edge-sensitive level 7 request, which cannot be masked.
30 — 21
19 — 0
Field
Exception vector table base address
—
Reset
0000_0000_0000_0000_0000_0000_0000_0000
R/W
Written from a BDM serial command or from the CPU using the MOVEC instruction.
VBR can be read from the debug module only. The upper 12 bits are returned, the
low-order 20 bits are undefined.
Rc [11-0]
0x801
Figure 3-4 Vector Base Register (VBR)
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Freescale Semiconductor, Inc.
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