Programming Model

Table 29-9describes DBR fields.

 

 

Table 29-9. DBR Field Descriptions

 

 

 

Bits

Name

Description

 

 

 

31–0

Data

Data breakpoint value. Contains the value to be compared with the data value from the processor’s local bus

 

 

as a breakpoint trigger.

 

 

 

Table 29-10describes DBMR fields.

 

 

Table 29-10. DBMR Field Descriptions

 

 

 

Bits

Name

Description

 

 

 

31–0

Mask

Data breakpoint mask. The 32-bit mask for the data breakpoint trigger. Clearing a DBR bit allows the

 

 

corresponding DBR bit to be compared to the appropriate bit of the processor’s local data bus. Setting a

 

 

DBMR bit causes that bit to be ignored.

 

 

 

The DBR supports both aligned and misaligned references. Table 29-11shows relationships between processor address, access size, and location within the 32-bit data bus.

Table 29-11. Access Size and Operand Data Location

A[1:0]

Access Size

Operand Location

 

 

 

00

Byte

D[31:24]

 

 

 

01

Byte

D[23:16]

 

 

 

10

Byte

D[15:8]

 

 

 

11

Byte

D[7:0]

 

 

 

0x

Word

D[31:16]

 

 

 

1x

Word

D[15:0]

 

 

 

xx

Longword

D[31:0]

 

 

 

29.4.6Program Counter Breakpoint/Mask Registers (PBR, PBMR)

The PBR defines an instruction address for use as part of the trigger. This register’s contents are compared with the processor’s program counter register when TDR is configured appropriately. PBR bits are masked by setting corresponding PBMR bits. Results are compared with the processor’s program counter register, as defined in TDR. Figure 29-9shows the PC breakpoint register.

MOTOROLA

Chapter 29. Debug Support

29-13

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Image 685
Motorola MCF5281 Program Counter Breakpoint/Mask Registers PBR, Pbmr, 9describes DBR fields, 10describes Dbmr fields