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37.3.2.3
MDO - Message Data Out
Message Data Out (MDO) are output pins used for uploading OTM, BTM, DTM, and other messages to
the development tool. The development tool should sample MDO on the rising edge of MCKO. The width
of the MDO bus used is determined by reset configuration.
37.3.2.4
MSEO - Message Start/End Out
Message Start/End Out (MSEO) is an output pin that indicates when a message on the MDO pins has
started, when a variable length packet has ended, or when the message has ended. The development tool
should sample MSEO on the rising edge of MCKO.
37.3.2.5
TCK - Test Clock Input
Test Clock Input (TCK) pin is used to synchronize the test logic and control register access through the
JTAG port.
37.3.2.6
TDI - Test Data Input
Test Data Input (TDI) pin receives serial test instruction and data. TDI is sampled on the rising edge of
TCK.
37.3.2.7
TDO - Nexus Test Data Output
Test Data Output (TDO) pin transmits serial output for instructions and data. TDO is three-stateable and
is actively driven in the SHIFT-IR and SHIFT-DR controller states. TDO is updated on the falling edge of
TCK and sampled by the development tool on the rising edge of TCK.
37.3.2.8
TMS - Test Mode Select
Test Mode Select Input (TMS) pin is used to sequence the IEEE 1149.1-2001 TAP controller state
machine. TMS is sampled on the rising edge of TCK.
37.4
Register definition
This section provides a detailed description of the NPC registers accessible to the end user. Individual
bit-level descriptions and reset states of the registers are included.
Table 37-4
shows the NPC registers by index values. The registers are not memory-mapped and can only
be accessed via the TAP. The NPC block does not implement the client select control register because the
value does not matter when accessing the registers. Note that the bypass and instruction registers have no
index values. These registers are not accessed in the same manner as Nexus client registers. Refer to the
individual register descriptions for more detail.
Freescale Semiconductor
MPC5644A Microcontroller Reference Manual, Rev. 6
Nexus Port Controller (NPC)
1677
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