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ColdFire Core
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
2-8
Freescale Semiconductor
2.2.2.1
Status Register (SR)
The SR stores the processor status, the interrupt priority mask, and other control bits. Supervisor software
can read or write the entire SR; user software can read or write only SR[7–0], described in
“Condition Code Register (CCR)
.” The control bits indicate processor states—trace mode (T), supervisor
or user mode (S), and master or interrupt state (M). SR is set to 0x27
xx
after reset.
describes SR fields.
2.2.2.2
Vector Base Register (VBR)
The VBR holds 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. VBR[19–0] are not
implemented and are assumed to be zero, forcing the vector table to be aligned on a 0-modulo-1-Mbyte
boundary.
15
8
7
0
System Byte
Condition Code Register (CCR)
Field
T
—
S
M
—
I
—
X
N
Z
V
C
Reset
0
0
1
0
0
111
000
—
—
—
—
—
R/W R/W
R
R/W
R/W
R
R/W
R
R/W
R/W
R/W
R/W
R/W
Figure 2-5. Status Register (SR)
Table 2-3. Status Field Descriptions
Bits
Name
Description
15
T
Trace enable. When T is set, the processor performs a trace exception after every instruction.
13
S
Supervisor/user state. Indicates whether the processor is in supervisor or user mode
0 User mode
1 Supervisor mode
12
M
Master/interrupt state. Cleared by an interrupt exception. It can be set by software during execution
of the RTE or move to SR instructions so the OS can emulate an interrupt stack pointer.
10–8
I
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.
7–0
CCR
31
20 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 2-6. Vector Base Register (VBR)