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Chapter 8 S12X Debug (S12XDBGV3) Module
MC9S12XE-Family Reference Manual , Rev. 1.07
322
Freescale Semiconductor
Table 8-30
shows the effect for RWE and RW on the comparison conditions. These bits are not useful for
tagged operations since the trigger occurs based on the tagged opcode reaching the execution stage of the
instruction queue. Thus these bits are ignored if tagged triggering is selected.
6
SZ
(Comparators
B and D)
Size Comparator Value Bit
— The SZ bit selects either word or byte access size in comparison for the
associated comparator. This bit is ignored if the SZE bit is cleared or if the TAG bit in the same register is set.
This bit position has NDB functionality for comparators A and C
0 Word access size will be compared
1 Byte access size will be compared
5
TAG
Tag Select
— This bit controls whether the comparator match will cause a trigger or tag the opcode at the
matched address. Tagged opcodes trigger only if they reach the execution stage of the instruction queue.
0 Trigger immediately on match
1 On match, tag the opcode. If the opcode is about to be executed a trigger is generated
4
BRK
Break
— This bit controls whether a channel match terminates a debug session immediately, independent
of state sequencer state. To generate an immediate breakpoint the module breakpoints must be enabled
using DBGBRK.
0 The debug session termination is dependent upon the state sequencer and trigger conditions.
1 A match on this channel terminates the debug session immediately; breakpoints if active are generated,
tracing, if active, is terminated and the module disarmed.
3
RW
Read/Write Comparator Value Bit
— The RW bit controls whether read or write is used in compare for the
associated comparator . The RW bit is not used if RWE = 0.
0 Write cycle will be matched
1 Read cycle will be matched
2
RWE
Read/Write Enable Bit
— The RWE bit controls whether read or write comparison is enabled for the
associated comparator. This bit is not used for tagged operations.
0 Read/Write is not used in comparison
1 Read/Write is used in comparison
1
SRC
Determines mapping of comparator to CPU12X or XGATE
0 The comparator is mapped to CPU12X buses
1 The comparator is mapped to XGATE address and data buses
0
COMPE
Determines if comparator is enabled
0 The comparator is not enabled
1 The comparator is enabled for state sequence triggers or tag generation
Table 8-30. Read or Write Comparison Logic Table
RWE Bit
RW Bit
RW Signal
Comment
0
x
0
RW not used in comparison
0
x
1
RW not used in comparison
1
0
0
Write
1
0
1
No match
1
1
0
No match
1
1
1
Read
Table 8-29. DBGXCTL Field Descriptions (continued)
Field
Description