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Debug Module
MCF52211 ColdFire® Integrated Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 28-7
NOTE
Debug control registers can be written by the external development system
or the CPU through the WDEBUG instruction. These control registers are
write-only from the programming model and they can be written through the
BDM port using the
WDMREG command. In addition, the
configuration/status register (CSR) can be read through the BDM port using
the
RDMREG command.
The ColdFire debug architecture supports a number of hardware breakpoint registers, that can be
configured into single- or double-level triggers based on the PC or operand address ranges with an optional
inclusion of specific data values.
28.4.1 Shared Debug Resources
The debug module revision A implementation provides a common hardware structure for BDM and
breakpoint functionality. Certain hardware structures are used for BDM and breakpoint purposes as shown
in Table 28-5.
Therefore, loading a register to perform a specific function that shares hardware resources is destructive
to the shared function. For example, if an operand address breakpoint is loaded into the debug module, a
BDM command to access memory overwrites an address breakpoint in ABHR. If a data breakpoint is
configured, a BDM write command overwrites the data breakpoint in DBR.
Revision B added hardware registers to eliminate these shared functions. The BAAR is used to specify bus
attributes for BDM memory commands and has the same format as the LSB of the AATR. The registers
containing the BDM memory address and the BDM data are not program visible.
28.4.2 Configuration/Status Register (CSR)
The CSR defines the debug configuration for the processor and memory subsystem and contains status
information from the breakpoint logic. CSR is write-only from the programming model. It can be read
from and written to through the BDM port. CSR is accessible in supervisor mode as debug control register
0x00 using the WDEBUG instruction and through the BDM port using the RDMREG and WDMREG
commands.
Table 28-5. Shared BDM/Breakpoint Hardware
Register BDM Function Breakpoint Function
AATR Bus attributes for all memory commands Attributes for address breakpoint
ABHR Address for all memory commands Address for address breakpoint
DBR Data for all BDM write commands Data for data breakpoint