mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 771

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

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
Comparators B and D feature SZ and SZE control bits. If SZE is clear, then the comparator address match
qualification 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
specified type of access causes a match. Thus if configured for a byte access of a particular address, a word
access covering the same address does not lead to match.
20.4.2.3
When using the AB comparator pair for a range comparison, the data bus can also be used for qualification
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 qualification 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 configured for range comparisons and tagging,
the ranges are accurate only to word boundaries.
20.4.2.3.1
In the Inside Range comparator mode, either comparator pair A and B or comparator pair C and D can be
configured for range comparisons. This configuration depends upon the control register (DBGC2). The
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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.
Comparators
Comparators
Comparators
Comparators
Comparator
A and C
B and D
B and D
B and D
Exact Address Comparator Match (Comparators B and D)
Range Comparisons
Inside Range (CompAC_Addr
Table 20-37. Comparator Access Size Considerations
Address
ADDR[n]
ADDR[n]
ADDR[n]
ADDR[n]
MC9S12XDP512 Data Sheet, Rev. 2.17
SZE
—
0
1
1
SZ8
—
X
0
1
address
Word and byte accesses of ADDR[n]
Word and byte accesses of ADDR[n]
Word accesses of ADDR[n]
Condition For Valid Match
MOVW #$WORD ADDR[n]
MOVW #$WORD ADDR[n]
MOVW #$WORD ADDR[n]
Byte accesses of ADDR[n]
MOVB #$BYTE ADDR[n]
MOVB #$BYTE ADDR[n]
MOVB #$BYTE ADDR[n]
CompBD_Addr)
Chapter 20 S12X Debug (S12XDBGV3) Module
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