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Development Support
18-6
MPC801 USER’S MANUAL
MOTOROLA
18
18.1.1.5.3 Synchronizing the Trace Window to the Internal Core Events.
and negation of the VSYNC signal is accomplished using the serial interface implemented
in the development port. To synchronize the assertion and negation of VSYNC to an internal
core event, the internal breakpoints hardware should be used with the debug mode. This
method is available only when debug mode is enabled. For more information on debug
mode, refer to
Section 18.3 Development System Interface
The assertion
.
To synchronize the trace window to the internal core events, follow these steps:
1. Enter debug mode either immediately out of reset of using the debug mode request.
2. Using the control registers defined in
Section 18.2 Watchpoint And Breakpoint
Generation
, program the hardware to break on the event that marks the start of the
trace window.
3. Enable debug mode entry for the programmed breakpoint in the debug enable register
(see Table 18-18).
4. Return to the regular code run.
5. The hardware generates a breakpoint when the event in question is detected and the
machine enters debug mode.
6. Program the hardware to break on the event that marks the end of the trace window.
7. Assert the VSYNC signal.
8. Return to the regular code run. The first report on the VF pins is VSYNC, where
VF =’011’.
9. The external hardware starts sampling the program trace information after the VF pins
indicate VSYNC.
10.The hardware generates a breakpoint when the event in question is detected and the
machine enters debug mode.
11.Negate VSYNC.
12.Return to the regular code run (issue an
rfi
VSYNC, where VF =’011’.
13.The external hardware stops sampling the program trace information after recognizing
VSYNC on the VF pins.
). The first encoding on the VF pins is
18.1.1.5.4 Detecting the Trace Window Start Address.
VF, VFLS, and the address of the cycles marked program trace cycle should all start
immediately after reset is negated. The start address is the first address in the program trace
cycle buffer. When using window trace, latching VF, VFLS, and the address of the cycles
marked as program trace cycle should all start immediately after the first VSYNC signal is
recognized on the VF pins. The start address of the trace window should be calculated
according to the first two VF pin reports. Assume VF1 and VF2 are the first two VF pin
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. The following table should be used
to calculate the trace window start address.
When using back trace, latching