Nexus Development Interface (NDI) RM0046
856/936 Doc ID 16912 Rev 5
Note: If the e200z0 core has executed a wait instruction, then the Nexus1 controller clocks are
gated off. While the core is in this state, it is not possible to perform Nexus read/write
operations.
36.5 Modes of operation
The NDI block is in reset when the TAP controller state machine is in the TEST-LOGIC-
RESET state. The TEST-LOGIC-RESET state is entered on the assertion of the power-on
reset signal or through state machine transitions controlled by TMS. Ownership of the TAP is
achieved by loading the appropriate enable instruction for the desired Nexus client in the
JTAGC controller (JTAGC) block.
The NPC transitions out of the reset state immediately following negation of power-on reset.
36.5.1 Nexus reset
In Nexus reset mode, the following actions occur:
● Register values default back to their reset values.
● The message queues are marked as empty.
● The TDO output buffer is disabled if the NDI has control of the TAP.
● The TDI, TMS, and TCK inputs are ignored.
● The NDI block indicates to the MCU that it is not using the auxiliary output port. This
indication can be used to tristate the output pins or use them for another function.
36.5.2 NDI modes
Censored mode
The NDI supports internal flash censorship mode by preventing the transmission of trace
messages and Nexus access to memory-mapped resources when censorship is enabled.
Stop mode
Stop mode logic is implemented in the Nexus port controller (NPC). When a request is
made to enter stop mode, the NDI block completes monitoring of any pending bus
transaction, transmits all messages already queued, and acknowledges the stop request.
After the acknowledgment, the system clock input are shut off by the clock driver on the
device. While the clocks are shut off, the development tool cannot access NDI registers via
the JTAG port.
36.6 External signal description
All signals are shared by all the individual blocks that make up the NDI block. The Nexus
port controller (NPC) block controls the signal sharing.
Refer to 3, “Signal Description for detailed signal descriptions.
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