8.11.1. Pattern generator modes of operation

There are a number of patterns supported to enable a number of metrics to be determined, for example, timing between pins, data edge timing, voltage fluctuations, ground bounce, and cross talk. When examining the trace port, there are two pattern modes you can choose:

Timed

Each pattern runs for a programmable number of TRACECLKIN cycles after which the pattern generator unit reverts back to an off state where normal trace is output, assuming trace output is enabled. The first thing the trace port outputs after returning to normal trace is a synchronization packet. This is useful with special trace port analyzers and capture devices that are aware of the pattern generator, and so the TPIU can be set to a standard configuration that the capture device is expecting. The preset test pattern can then be run, by the end of which, the TCD is calibrated ready for normal operation, which the TPIU switches to automatically, without the requirement to reprogram the TPIU.

Continuous

The selected pattern runs continuously until manually disabled. This is primarily intended for manual refinement of electrical characteristics and timing.

Off

When neither of the other two modes is selected the device reverts to outputting any trace data. After timed operation finishes, the pattern generator reverts back to the Off Mode.

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