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MPC555
/
MPC556
DEVELOPMENT SUPPORT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
21-6
ternal event of the CPU, it is possible to use the internal breakpoints together with de-
bug mode. This method is available only when debug mode is enabled. For more
information on debug mode refer to
21.4 Development System Interface
The following is an example of steps that enable the user to synchronize the trace win-
dow to the CPU internal events:
1. Enter debug mode, either immediately out of reset or using the debug mode re-
quest
2. Program the hardware to break on the event that marks the start of the trace
window using the control registers defined in
3. Enable debug mode entry for the programmed breakpoint in the debug enable
21.7.12 Debug Enable Register (DER)
4. Return to the regular code run (see
5. The hardware generates a breakpoint when the programmed event is detected
and the machine enters debug mode (see
)
6. Program the hardware to break on the event that marks the end of the trace
window
7. Assert VSYNC
8. Return to the regular code run. The first report on the VF pins is a VSYNC (VF
= 011).
9. The external hardware starts sampling the program trace information upon the
report on the VF pins of VSYNC
10. The hardware generates a breakpoint when the programmed event is detected
and the machine enters debug mode
11. Negate VSYNC
12. Return to the regular code run (issue an
rfi
). The first report on the VF pins is a
VSYNC (VF = 011)
13. The external hardware stops sampling the program trace information upon the
report on the VF pins of VSYNC
21.2.4.2 Detecting the Trace Window Start Address
When using
back trace
, latching the value of the status pins (VF and VFLS), and the
address of the cycles marked as program trace cycle, should start immediately after
the negation of reset. The start address is the first address in the program trace cycle
buffer.
When using
window trace
, latching the value of the status pins (VF and VFLS), and
the address of the cycles marked as program trace cycle, should start immediately af-
ter the first VSYNC is reported on the VF pins. The start address of the trace window
should be calculated according to first two VF pins reports.
Assuming that VF1 and VF2 are the two first VF pins reports and T1 and T2 are the
two addresses of the first two cycles marked with the program trace cycle attribute that
were latched in the trace buffer, use the following table to calculate the trace window
start address.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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