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MC9S12XD64MAA Datasheet, PDF (769/1348 Pages) Freescale Semiconductor, Inc – ATD Input Enable Register 0 | |||
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Chapter 20 S12X Debug (S12XDBGV3) Module
Comparators A and C feature an NDB control bit to determine if a match occurs when the data bus differs
to comparator register contents or when the data bus is equivalent to the comparator register contents.
20.4.2.2 Exact Address Comparator Match (Comparators B and D)
Comparators B and D feature SZ and SZE control bits. If SZE is clear, then the comparator address match
qualiï¬cation functions the same as for comparators A and C.
If the SZE bit is set the access size (word or byte) is compared with the SZ bit value such that only the
speciï¬ed type of access causes a match. Thus if conï¬gured for a byte access of a particular address, a word
access covering the same address does not lead to match.
Table 20-37. Comparator Access Size Considerations
Comparator
Comparators
A and C
Comparators
B and D
Comparators
B and D
Address
ADDR[n]
SZE SZ8
ââ
ADDR[n]
0
X
ADDR[n]
1
0
Condition For Valid Match
Word and byte accesses of ADDR[n]1
MOVB #$BYTE ADDR[n]
MOVW #$WORD ADDR[n]
Word and byte accesses of ADDR[n]1
MOVB #$BYTE ADDR[n]
MOVW #$WORD ADDR[n]
Word accesses of ADDR[n]1
MOVW #$WORD ADDR[n]
Comparators
B and D
ADDR[n]
1
1
Byte accesses of ADDR[n]
MOVB #$BYTE ADDR[n]
1 A word access of ADDR[n-1] also accesses ADDR[n] but does not generate a match.
The comparator address register must contain the exact address used in the code.
20.4.2.3 Range Comparisons
When using the AB comparator pair for a range comparison, the data bus can also be used for qualiï¬cation
by using the comparator A data and data mask registers. Furthermore the DBGACTL RW and RWE bits
can be used to qualify the range comparison on either a read or a write access. The corresponding
DBGBCTL bits are ignored. Similarly when using the CD comparator pair for a range comparison, the
data bus can also be used for qualiï¬cation by using the comparator C data and data mask registers.
Furthermore the DBGCCTL RW and RWE bits can be used to qualify the range comparison on either a
read or a write access if tagging is not selected. The corresponding DBGDCTL bits are ignored. The SZE
and SZ control bits are ignored in range mode. The comparator A and C TAG bits are used to tag range
comparisons for the AB and CD ranges respectively. The comparator B and D TAG bits are ignored in
range modes. In order for a range comparison using comparators A and B, both COMPEA and COMPEB
must be set; to disable range comparisons both must be cleared. Similarly for a range CD comparison, both
COMPEC and COMPED must be set. If a range mode is selected SRCA and SRCC select the source
(S12X or XGATE), SRCB and SRCD are ignored. When conï¬gured for range comparisons and tagging,
the ranges are accurate only to word boundaries.
20.4.2.3.1 Inside Range (CompAC_Addr ⤠address ⤠CompBD_Addr)
In the Inside Range comparator mode, either comparator pair A and B or comparator pair C and D can be
conï¬gured for range comparisons. This conï¬guration depends upon the control register (DBGC2). The
MC9S12XDP512 Data Sheet, Rev. 2.21
Freescale Semiconductor
771
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