ARM reset signals

All ARM processors have a main processor reset that might be called nRESET, BnRES, or HRESET. This is asserted by one or more of these conditions:

Any ARM processor including the JTAG interface has a second reset input called nTRST (TAP Reset). This resets the EmbeddedICE logic, the Test Access Port (TAP) controller, and the boundary scan cells. It is activated by remote JTAG reset (from DSTREAM).

It is strongly recommended that both signals are separately available on the JTAG connector. If the nRESET and nTRST signals are linked together, resetting the system also resets the TAP controller. This means that:

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