Processor Register Description

Two 32-bit access control registers (ACR0, ACR1)

Two 32-bit memory base address registers (RAMBAR, FLASHBAR)

1570

(CCR) SR

31

OTHER_A7

VBR

CACR

ACR0

ACR1

FLASHBAR

RAMBAR

STATUS

SUPERVISOR A7 STACK POINTER

VECTOR BASE REGISTER

CACHE

CONTROL

ACCESS

CONTROL

ACCESS

CONTROL

FLASH BASE ADDRESS REGISTER

RAM BASE ADDRESSREGISTER

Figure 2-5. Supervisor Programming Model

The following paragraphs describe the supervisor programming model registers.

2.2.3.1Status Register (SR)

The SR stores the processor status and includes the CCR, the interrupt priority mask, and other control bits. In 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 bit). All defined bits in the SR have read/write access when in supervisor mode.

 

 

 

System Byte

 

 

 

 

Condition Code Register (CCR)

 

 

15

14

13

12

11

10

8

7

6

5

4

3

2

1

0

T

0

S

M

0

I

0

0

0

X

N

Z

V

C

 

 

 

 

Figure 2-6. Status Register

 

 

 

 

 

Table 2-2. SR Field Descriptions

 

 

 

 

 

 

 

 

 

 

Bits

Name

 

Description

 

 

 

 

 

 

 

 

 

15

T

 

Trace enable. When set, the processor performs a trace exception after

 

 

 

 

 

every instruction.

 

 

 

 

 

 

 

 

 

 

14

 

Reserved, should be cleared.

 

 

 

 

 

 

 

 

 

13

S

 

Supervisor/user state. Denotes whether the processor is in supervisor

 

 

 

 

 

mode (S = 1) or user mode (S = 0).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2-6

 

 

 

MCF5282 User’s Manual

MOTOROLA

Page 78
Image 78
Motorola MCF5282, MCF5281 user manual Status Register SR, System Byte Condition Code Register CCR, Bits