Emulation Design Considerations
15-20
on the EMU0/1-OUT signal. This pulse must be longer than one TCK
period to affect the devices, but less than 10
µ
s to avoid possible conflicts
or retriggering, once the emulation software clears the device’s pins.
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During a RUNB debugger command or other external analysis count, the
EMU0/1 pins on the target device become totem-pole outputs. The EMU1
pin is a ripple carry-out of the internal counter. EMU0 becomes a
processor-halted signal. During a RUNB or other external analysis count,
the EMU0/1-IN signal to all boards must remain in the high (disabled)
state. You must provide some type of external input (XCNT_ENABLE) to
the PAL to disable the PAL from driving EMU0/1-IN to a low state.
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If sources other than TI processors (such as logic analyzers) are used to
drive EMU0/1, their signal lines must be isolated by open-collector drivers
and be inactive during RUNB and other external analysis counts.
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You must connect the EMU0/1-OUT signals to the emulation header or di-
rectly to a test bus controller.