Pulse nTRST Step

Pulse nTRST is a step which may be used in a Test Reset Sequence for a subchain, if its TAP group has been configured in the pin mapping with an nTRST pin. The nTRST pin will be held low whilst TCK is cycled, then nTRST will be driven high, and TCK cycled once more. TMS will also be held high for the duration of this step.

It is also available in projects without subchains if there are any nTRST pins defined in the pin mapping.

In the example waveform diagram above, only one nTRST, TCK and TMS pin are being shown. However, the pins that are actually driven will be resolved when the step executes.

Pin Resolution

Dynamic Projects

In projects where subchains and profiles are configured, the pins used by the Pulse nTRST step are taken form the TAP group of the subchain the reset sequence is assigned to. If the TAP group spans multiple TDI pins, and so has multiple nTRST pins, these will all be driven.

Non-dynamic Projects

For projects with no subchains defined, all the pins of each type that are present in the pin mapping will be driven.

Use With Other Steps and Pins

Assuming the conditions for the Pulse nTRST step to be available in a sequence, it may be used just like any of the other steps.

Any pins driven during the step will retain their values when the step has finished executing. For example, see how the nTRST and TMS pins are left high, and the TCK pin is left low after the Pulse nTRST step, overriding the drive values set before the step.