Datasheet

Signal Description
MOTOROLA MCF5206e USER’S MANUAL 2-19
not driven low, its value will default to a logic level of 1. However, if JTAG is not used,
TRST can either be tied to ground or, if TCK is clocked, it can be tied to VDD. The former
connection places the JTAG controller in the test logic reset state immediately, while the
latter connection causes the JTAG controller (if TMS is a logic 1) to eventually end up in
the test logic reset state after five clocks of TCK.
2.15.3 Test Mode Select (TMS/BKPT)
The MTMOD signal determines the function of this dual-purpose pin. If MTMOD = 0, then
the TMS function is selected. If MTMOD =1, the BKPT function is selected. MTMOD
should not change while RSTI = 1.
The TMS input signal provides the JTAG controller with information to determine which
test operation should be performed. The value of TMS and the current state of the internal
16-state JTAG controller state machine at the rising edge of TCK determine whether the
JTAG controller holds its current state or advances to the next state. This directly controls
whether JTAG data or instruction operations occur. TMS has an internal pullup so that if
it is not driven low, its value will default to a logic level of 1. However, if TMS is not used,
it should be tied to VDD.
2.15.4 Test Data Input (TDI/DSI)
The MTMOD signal determines the function of this dual-purpose pin. If MTMOD = 0, then
TDI is selected. If MTMOD = 1, then DSI is selected. MTMOD should not change while
RSTI = 1.
The TDI input signal provides the serial data port for loading the various JTAG shift
registers (the boundary scan register, the bypass register, and the instruction register).
Shifting in of data depends on the state of the JTAG controller state machine and the
instruction currently in the instruction register. This data shift occurs on the rising edge of
TCK. TDI also has an internal pullup so that if it is not driven low, its value will default to
a logic level of 1. However, if TDI will not be used, it should be tied to VDD.
2.15.5 Test Data Output (TDO/DSO)
The MTMOD signal determines the function of this dual-purpose pin. When MTMOD = 0,
TDO is selected. When MTMOD = 1, then DSO is selected. MTMOD should not change
while RSTI = 1.
The TDO output signal provides the serial data port for outputting data from the JTAG
logic. Shifting out of data depends on the state of the JTAG controller state machine and
the instruction currently in the instruction register. This data shift occurs on the falling edge
of TCK. When TDO is not outputting test data, it is placed in a high-impedence state. TDO
can also be three-stated to allow bussed or parallel connections to other devices having
JTAG.
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