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Chapter 16 S12X Debug (S12XDBGV3) Module
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
775
16.3.2.8.1
Debug Comparator Control Register (DBGXCTL)
The contents of this register bits 7 and 6 differ depending upon which comparator registers are visible in
the 8-byte window of the DBG module register address map.
Read: Anytime. See
Table 16-28 for visible register encoding.
Write: If DBG not armed. See
Table 16-28 for visible register encoding.
The DBGC1_COMRV bits determine which comparator control, address, data and datamask registers are
Table 16-28. Comparator Address Register Visibility
Address: 0x0028
76543210
R0
NDB
TAG
BRK
RW
RWE
SRC
COMPE
W
Reset
0
00000
= Unimplemented or Reserved
Figure 16-13. Debug Comparator Control Register (Comparators A and C)
Address: 0x0028
76543210
R
SZE
SZ
TAG
BRK
RW
RWE
SRC
COMPE
W
Reset
0
00000
Figure 16-14. Debug Comparator Control Register (Comparators B and D)
COMRV
Visible Comparator
00
DBGACTL, DBGAAH ,DBGAAM, DBGAAL, DBGADH, DBGADL, DBGADHM, DBGADLM
01
DBGBCTL, DBGBAH, DBGBAM, DBGBAL
10
DBGCCTL, DBGCAH, DBGCAM, DBGCAL, DBGCDH, DBGCDL, DBGCDHM, DBGCDLM
11
DBGDCTL, DBGDAH, DBGDAM, DBGDAL
Table 16-29. DBGXCTL Field Descriptions
Field
Description
7
SZE
(Comparators
B nd D)
Size Comparator Enable Bit — The SZE bit controls whether access size comparison is enabled for the
associated comparator. This bit is ignored if the TAG bit in the same register is set.
0 Word/Byte access size is not used in comparison
1 Word/Byte access size is used in comparison
6
NDB
(Comparators
A and C
Not Data Bus — The NDB bit controls whether the match occurs when the data bus matches the comparator
register value or when the data bus differs from the register value. Furthermore data bus bits can be
individually masked using the comparator data mask registers. This bit is only available for comparators A
and C. This bit is ignored if the TAG bit in the same register is set. This bit position has an SZ functionality for
comparators B and D.
0 Match on data bus equivalence to comparator register contents
1 Match on data bus difference to comparator register contents