Real-Time Debug Support
MOTOROLA
Debug Support
19-25
Bdm Read ACCx (
rcreg macsr; // read current macsr contents & save
wcreg #0,macsr; // disable all rounding modes
rcreg ACCx; // read the desired accumulator
wcreg #saved_data,macsr; // restore the original macsr
)
Likewise to write an accumulator register, the following BDM sequence is needed:
Bdm Write ACCx (
rcreg macsr; // read current macsr contents & save
wcreg #0,macsr; // disable all rounding modes
wcreg #data,ACCx; // write the desired accumulator
wcreg #saved_data,macsr; // restore the original macsr
)
Additionally, writes to the accumulator extension registers must be performed after the corresponding
accumulators are updated because a write to any accumulator alters the corresponding extension register
contents.
Command Sequence:
Figure 19-24 Read Control Register Command Sequence
Operand Data:
The single operand is the 32-bit Rc control register select field.
Result Data:
The contents of the selected control register are returned as a longword value. The data is returned most
significant word first. For those control registers with widths less than 32 bits, only the implemented portion
of the register is guaranteed to be correct. The remaining bits of the longword are undefined.
19.4
REAL-TIME DEBUG SUPPORT
The ColdFire Family provides support for the debug of real-time applications. For these types of
embedded systems, the processor cannot be halted during debug, but must continue to operate. The
foundation of this area of debug support is that while the processor cannot be halted to allow debugging,
the system can generally tolerate small intrusions into the real-time operation.
The debug module provides a number of hardware resources to support various hardware breakpoint
functions. Specifically, three types of breakpoints are supported: PC with mask, operand address range,
and data with mask. These three basic breakpoints can be configured into one- or two-level triggers with
the exact trigger response also programmable. The debug module programming model is accessible from
MS ADDR
“NOT READY”
MS ADDR
“NOT READY”
READ
REGISTER
XXX
“NOT READY”
XXX
MS RESULT
XXX
BERR
NEXT CMD
LS RESULT
NEXT CMD
“NOT READY”
RCREG
???
CONTROL
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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