
Debug Support
MOTOROLA
ColdFire2/2M User’s Manual
For More Information On This Product,
Go to: www.freescale.com
7-29
required functionality. All of these registers are treated as 32-bit quantities, regardless of the
actual number of bits in the implementation. The registers, known as the debug control
registers, are accessed through the BDM port using two new BDM commands:
WDMREG
and
RDMREG
. These commands contain a 4-bit field, DRc, which specifies the particular
register being accessed.
These registers are also accessible from the processor’s supervisor programming model
through the execution of the WDEBUG instruction. Thus, the breakpoint hardware within the
debug module may be accessed by the external development system using the serial
interface, or by the operating system running on the processor core. It is the responsibility
of the software to guarantee that all accesses to these resources are serialized and logically
consistent. The hardware provides a locking mechanism in the
CSR
to allow the external
development system to disable any attempted writes by the processor to the breakpoint
registers (setting IPW = 1). The BDM commands should not be issued whenever the
ColdFire2/2M is accessing the debug module registers using the WDEBUG instruction.
Figure 7-8
illustrates the debug module programming model.
7.4.2.1 ADDRESS BREAKPOINT REGISTERS (ABLR, ABHR).
The address breakpoint
registers define a region in the operand address space of the processor that can be used as
part of the trigger. The full 32-bits of the ABLR and ABHR values are compared with the
internal address signals of the ColdFire2/2M. The trigger definition register (
TDR
)
determines if the trigger is the inclusive range bound by ABLR and ABHR, all addresses
outside this range, or the address in ABLR only. The ABHR is accessible in supervisor mode
as debug control register $C using the WDEBUG instruction and via the BDM port using the
RDMREG and WDMREG commands. The ABLR is accessible in supervisor mode as debug
control register $D using the WDEBUG instruction and via the BDM port using the
WDMREG commands. The ABHR is overwritten by the BDM hardware when accessing
memory as described in
Section 7.4.1.2 Reuse of Debug Module Hardware
.
Figure 7-8. Debug Programming Model
ADDRESS
BREAKPOINT REGISTERS
PC BREAKPOINT
REGISTERS
DATA BREAKPOINT
REGISTERS
ABLR
ABHR
PBR
PBMR
DBMR
DBR
TDR
15
0
31
TRIGGER DEFINITION
REGISTER
CONFIGURATION/
STATUS
ADDRESS ATTRIBUTE
REGISTER
AATR
7
0
15
CSR
F
Freescale Semiconductor, Inc.
n
.