Datasheet

Chapter 8 S12X Debug (S12XDBGV3) Module
MC9S12XE-Family Reference Manual Rev. 1.25
Freescale Semiconductor 321
8.3.2.8 Comparator Register Descriptions
Each comparator has a bank of registers that are visible through an 8-byte window in the S12XDBG
module register address map. Comparators A and C consist of 8 register bytes (3 address bus compare
registers, two data bus compare registers, two data bus mask registers and a control register).
Comparators B and D consist of four register bytes (three address bus compare registers and a control
register).
Each set of comparator registers is accessible in the same 8-byte window of the register address map and
can be accessed using the COMRV bits in the DBGC1 register. If the Comparators B or D are accessed
through the 8-byte window, then only the address and control bytes are visible, the 4 bytes associated with
data bus and data bus masking read as zero and cannot be written. Furthermore the control registers for
comparators B and D differ from those of comparators A and C.
8.3.2.8.1 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 8-29 for visible register encoding.
Table 8-28. Comparator Register Layout
0x0028 CONTROL Read/Write Comparators A,B,C,D
0x0029 ADDRESS HIGH Read/Write Comparators A,B,C,D
0x002A ADDRESS MEDIUM Read/Write Comparators A,B,C,D
0x002B ADDRESS LOW Read/Write Comparators A,B,C,D
0x002C DATA HIGH COMPARATOR Read/Write Comparator A and C only
0x002D DATA LOW COMPARATOR Read/Write Comparator A and C only
0x002E DATA HIGH MASK Read/Write Comparator A and C only
0x002F DATA LOW MASK Read/Write Comparator A and C only
Address: 0x0028
76543210
R0
NDB TAG BRK RW RWE SRC COMPE
W
Reset 00000000
= Unimplemented or Reserved
Figure 8-13. Debug Comparator Control Register (Comparators A and C)
Address: 0x0028
76543210
R
SZE SZ TAG BRK RW RWE SRC COMPE
W
Reset 00000000
Figure 8-14. Debug Comparator Control Register (Comparators B and D)