Slave Test Reset (STRST)
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 21-5

21.3.5 Test Data Out ( TDO)

Serial test data output is routed from the active shift register to this pin. To ensure setup and hold time for TDO when connected to TDI (of
another device), TDO switches at the TCK falling edge. TDO is driven while the TLM state machine is in the Shift-IR or Shift-DR states only;
it is tri-stated in all other TAP states. Except, for the first half clock after exiting the shift state, because of its falling edge timing.
21.4 Slave Test Reset (STRST)
STRST is the active-low reset from the TLM to all slave TAP blocks. STRST is asserted whenever the TLM state machine is in the Test Lo gic
Reset state. This is a result of TRST being asserted, or the TMS sequence.

21.4.1 Enable Slave—ENA [0: n]

Enable signals are decoded from the contents of the TLM:Link DR. There is one Enable signal for the TLM and one for each slave TAP block.
No more than one Enable signal can be asserted at one time. Each slave TAP block gates (logical AND) TMS with a unique Enable signal.
Any number of TLM:Link DR codes may activate any Enable signal. MPC5200B implements one TLM:Link DR code for each Enable signal.

21.4.2 Select DR Link—SEL [0: n]

Each slave TAP block generates one Select signal; its value is decoded from the contents of its IR. Any number of Select signals may be
asserted at any time; the TLM ignores all SEL[0:n] signals except from the active slave TAP (if any). Instruction codes that activate Select
may be different in each slave TAP block. Any number of instruction codes may activate Select, but the mandatory BYPASS, EXTEST, and
SAMPLE:PRELOAD instructions (and IDCODE, if implemented) must not. However, a slave is allowed to implement additional instructions
that behave identically to any of these instructions, except that Select is asserted and the normal DR is disabled.

21.4.3 Slave Test Data Out—STDO [0:n ]

Each slave TAP block provides a serial test data output. Just like TDO, all transitions of STDO[0:n ] must occur on the falling edge of TCK.
ENA[0 :n] and SEL [0: n] select either the active slave serial output data or the TLM serial output data to appear at the TDO pin.
21.5 TAP State Machines
All TAP state machines are the same, including the TLM, except for the single control signal. The TLM receives the external TMS signal
unmodified; all other (slave) TAP Controllers respond to unique versions of TMS combined with their unique Enable signal.