Data transfer is synchronized by the TRACECLK signal. See the following:
For capturing trace port signals synchronous to TRACECLK, the DSTREAM trace feature supports up to 600Mbps per trace signal using DDR clocking mode, or up to 480Mbps using SDR clocking mode. The following figure and table describe the timing for TRACECLK:
|Tperiod (min)||2.08ns||Clock period|
|Twh (min)||1.0ns||High pulse width|
|Twl (min)||1.0ns||Low pulse width|
The trace probe detects the target signaling reference voltage (VTref) and automatically adjusts its switching thresholds to VTref/2. For example, on a 3.3 volt target system, the switching thresholds are set to 1.65 volts.
If you power-up the DSTREAM unit when it is plugged into an unpowered target, or if you plug an unpowered DSTREAM unit into a powered target, trace functionality is not damaged.
If you connect an unpowered DSTREAM unit to a powered target, there is a maximum leakage current into the DSTREAM unit of ±10μA on any of the debug or trace signals.