Datasheet

S12S Debug Module (S12SDBGV2)
MC9S12G Family Reference Manual, Rev.1.23
Freescale Semiconductor 335
8.4.2.1.2 Comparator B
Comparator B offers address, direction (R/W) and access size (word/byte) comparison. If the SZE bit is
set the access size (word or byte) is compared with the SZ bit value such that only the specified size 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.
Assuming the access direction is not qualified (RWE=0), for simplicity, the size access considerations are
shown in Table 8-33.
Access direction can also be used to qualify a match for Comparator B in the same way as described for
Comparator C in Table 8-32.
8.4.2.1.3 Comparator A
Comparator A offers address, direction (R/W), access size (word/byte) and data bus comparison.
Table 8-34 lists access considerations with data bus comparison. On word accesses the data byte of the
lower address is mapped to DBGADH. Access direction can also be used to qualify a match for
Comparator A in the same way as described for Comparator C in Table 8-32.
Table 8-34. Comparator A Matches When Accessing ADDR[n]
Table 8-32. Comparator C Access Considerations
Condition For Valid Match Comp C Address RWE RW Examples
Read and write accesses of ADDR[n] ADDR[n]
1
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 from the code.
0 X LDAA ADDR[n]
STAA #$BYTE ADDR[n]
Write accesses of ADDR[n] ADDR[n] 1 0 STAA #$BYTE ADDR[n]
Read accesses of ADDR[n] ADDR[n] 1 1 LDAA #$BYTE ADDR[n]
Table 8-33. Comparator B Access Size Considerations
Condition For Valid Match Comp B Address RWE SZE SZ8 Examples
Word and byte accesses of ADDR[n] ADDR[n]
1
1
A word access of ADDR[n-1] also accesses ADDR[n] but does not generate a match.
The comparator address register must contain the exact address from the code.
0 0 X MOVB #$BYTE ADDR[n]
MOVW #$WORD ADDR[n]
Word accesses of ADDR[n] only ADDR[n] 0 1 0 MOVW #$WORD ADDR[n]
LDD ADDR[n]
Byte accesses of ADDR[n] only ADDR[n] 0 1 1 MOVB #$BYTE ADDR[n]
LDAB ADDR[n]
SZE SZ
DBGADHM,
DBGADLM
Access
DH=DBGADH, DL=DBGADL
Comment
0 X $0000 Byte
Word
No databus comparison