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ColdFire CF4e Core User’s Manual
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Debug C Definition of PSTDDATA Outputs
Setting CSR[TRC] forces the processor into emulation mode when trace exception
processing begins.
While operating in emulation mode, the processor exhibits the following properties:
Unmasked interrupt requests are serviced. The resulting interrupt exception stack
frame has FS[1] set to indicate the interrupt occurred while in emulator mode.
If CSR[MAP] = 1, all caching of memory and the SRAM module are disabled. All
memory accesses are forced into a specially mapped address space signaled by
TT = 0x2, TM = 0x5 or 0x6. This includes stack frame writes and the vector fetch
for the exception that forced entry into this mode.
The RTE instruction exits emulation mode. The processor status output port provides a
unique encoding for emulator mode entry (0xD) and exit (0x7).
11.6.2 Concurrent BDM and Processor Operation
The debug module supports concurrent operation of both the processor and most BDM
commands. BDM commands may be executed while the processor is running, except the
following:
Read/write address and data registers
Read/write control registers
For BDM commands that access memory, the debug module requests the processor’s local
bus. The processor responds by stalling the instruction fetch pipeline and waiting for
current bus activity to complete before freeing the local bus for the debug module to
perform its access. After the debug module bus cycle, the processor reclaims the bus.
NOTE:
Breakpoint registers must be carefully configured in a
development system if the processor is executing. The debug
module contains no hardware interlocks, so TDR and XTDR
should be disabled while breakpoint registers are loaded, after
which TDR and XTDR can be written to define the exact
trigger. This prevents spurious breakpoint triggers.
Because there are no hardware interlocks in the debug unit, no BDM operations are
allowed while the CPU is writing the debug’s registers (DSCLK must be inactive).
11.7 Debug C Definition of PSTDDATA Outputs
This section specifies the ColdFire processor and debug module’s generation of the
PSTDDATA output on an instruction basis. In general, the PSTDDATA output for an
instruction is defined as follows:
PSTDDATA = 0x1, {[0x89B], operand}
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