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IDT EJTAG System
Hardware Breakpoints
79RC32438 User Reference Manual
20 - 51
November 4, 2002
Notes
Data Breakpoint Value n (DBVn) Register
Compliance Level
: Required with data breakpoint n if data value compare is supported (indicated by
either NoSVmatch or NoLVmatch bits in DBS being 0), optional otherwise.
The Data Breakpoint Value n (DBVn) register has the value used in the condition for data breakpoint n.
It is located at drseg offset 0x2120 + 0x100 * n. Figure 20.19 shows the format of the DBVn register and
Table 20.40 describes the DBVn register field.
Figure 20.19 DBVn Register Format
Recommendations for Implementing Hardware Breakpoints
This section provides useful information for implementing instruction and data breakpoints.
BLM[7:0]
11:4
Byte lane mask for value compare on data
breakpoint. BLM[0] masks byte at bits [7:0]
of the data bus, BLM[1] masks byte at bits
[15:8], etc.:
0:
Compare corresponding byte lane
1:
Mask corresponding byte lane
Debug software must adjust for endianess
when programming this field.
BLM[7:4] are un-implemented for 32-bit
processors. BLM[7:0] are un-implemented
if value compare is not implemented, which
is the case when NoSVmatch and NoLV-
match bits in DBS are both 1. Bits are
read-only (R) and read as zeros if not
implemented.
R/W
Undefined
Required for
byte lanes in
implementa-
tion and if
value com-
pare, other-
wise not
implemented
TE
2
Use data breakpoint n as triggerpoint:
0:
Do not use it as triggerpoint
1:
Use it as triggerpoint
R/W
0
Required
BE
0
Use data breakpoint n as breakpoint:
0: Do not use it as breakpoint
1: Use it as breakpoint
R/W
0
Required
0
MSB:24,
22, 3, 1
Must be written as zeros; return zeros on
read.
0
0
Reserved
31
0
DBVn
Fields
Description
Read/
Write
Reset
State
Compli-
ance
Name
Bit
DBV
MSB:0
Data breakpoint data value for condition.
Debug software must adjust for endianess
when programming this field.
R/W
Undefined
Required
Table 20.40 DBVn Register Field Description
Fields
Description
Read/
Write
Reset
State
Compli-
ance
Name
Bit
Table 20.39 DBCn Register Field Description (Part 2 of 2)