MC9S12GRMV1 Datasheet, PDF (334/1292 Pages) Freescale Semiconductor, Inc – MC9S12G Family Reference Manual and Data Sheet

S12S Debug Module (S12SDBGV2)
SZE
SZ
DBGADHM,
DBGADLM
Access
DH=DBGADH, DL=DBGADL
0
X
0
X
0
X
$FF00
$00FF
$00FF
Byte, data(ADDR[n])=DH
Word, data(ADDR[n])=DH, data(ADDR[n+1])=X
Word, data(ADDR[n])=X, data(ADDR[n+1])=DL
Byte, data(ADDR[n])=X, data(ADDR[n+1])=DL
0
X
0
X
1
0
$FFFF
$FFFF
$0000
Word, data(ADDR[n])=DH, data(ADDR[n+1])=DL
Byte, data(ADDR[n])=DH, data(ADDR[n+1])=DL
Word
1
0
1
0
1
0
$00FF
$FF00
$FFFF
Word, data(ADDR[n])=X, data(ADDR[n+1])=DL
Word, data(ADDR[n])=DH, data(ADDR[n+1])=X
Word, data(ADDR[n])=DH, data(ADDR[n+1])=DL
1
1
1
1
$0000
$FF00
Byte
Byte, data(ADDR[n])=DH
Comment
Match data( ADDR[n])
Match data( ADDR[n+1])
Possible unintended match
Match data( ADDR[n], ADDR[n+1])
Possible unintended match
No databus comparison
Match only data at ADDR[n+1]
Match only data at ADDR[n]
Match data at ADDR[n] & ADDR[n+1]
No databus comparison
Match data at ADDR[n]
8.4.2.1.4 Comparator A Data Bus Comparison NDB Dependency
Comparator A features an NDB control bit, which allows data bus comparators to be configured to either
trigger on equivalence or trigger on difference. This allows monitoring of a difference in the contents of
an address location from an expected value.
When matching on an equivalence (NDB=0), each individual data bus bit position can be masked out by
clearing the corresponding mask bit (DBGADHM/DBGADLM) so that it is ignored in the comparison. A
match occurs when all data bus bits with corresponding mask bits set are equivalent. If all mask register
bits are clear, then a match is based on the address bus only, the data bus is ignored.
When matching on a difference, mask bits can be cleared to ignore bit positions. A match occurs when any
data bus bit with corresponding mask bit set is different. Clearing all mask bits, causes all bits to be ignored
and prevents a match because no difference can be detected. In this case address bus equivalence does not
cause a match.
NDB
0
0
1
1
Table 8-35. NDB and MASK bit dependency
DBGADHM[n] /
DBGADLM[n]
0
1
0
1
Comment
Do not compare data bus bit.
Compare data bus bit. Match on equivalence.
Do not compare data bus bit.
Compare data bus bit. Match on difference.
8.4.2.2 Range Comparisons
Using the AB comparator pair for a range comparison, the data bus can also be used for qualification by
using the comparator A data 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. The SZE and SZ control bits are ignored in range mode. The comparator A TAG bit is used to tag
MC9S12G Family Reference Manual, Rev.1.23
336
Freescale Semiconductor