MPC5125 datasheet(84/94 Pages) FREESCALE

84 / 94 page

MPC5125 Microcontroller Data Sheet, Rev. 4

System Design Information

Freescale Semiconductor

5.4

Pullup/Pulldown Resistor Requirements

The MPC5125 requires external pullup or pulldown resistors on certain pins.

5.4.1

Pulldown Resistor Requirements for TEST Pin

The MPC5125 requires a pulldown resistor on the test pin TEST.

5.5

JTAG

The MPC5125 has an IEEE 1149.1 JTAG interface to facilitate board/system testing. It also provides a common on-chip

processor (COP) interface, which shares the IEEE 1149.1 JTAG port.

The COP interface provides access to the MPC5125’s embedded e300 processor and to other on-chip resources. This interface

provides a means for executing test routines and for performing software development and debug functions.

5.5.1

JTAG_TRST

Boundary scan testing is enabled through the JTAG interface signals. The JTAG_TRST signal is optional in the IEEE 1149.1

specification but is provided on all processors that implement the Power Architecture. To obtain a reliable power-on reset

performance, the JTAG_TRST signal must be asserted during power-on reset.

5.5.1.1

TRST and PORESET

The JTAG interface can control the direction of the MPC5125 I/O pads via the boundary scan chain. The JTAG module must

be reset before the MPC5125 comes out of power-on reset; do this by asserting TRST before PORESET is released.

For more details, see the Reset and JTAG Timing Specification.

Figure 50. PORESET vs. TRST

5.5.2

e300 COP/BDM Interface

There are two possibilities to connect the JTAG interface: using it with a COP connector and without a COP connector.

5.5.2.1

Boards Interfacing the JTAG Port via a COP Connector

The MPC5125 functional pin interface and internal logic provides access to the embedded e300 processor core through the

Freescale standard COP/BDM interface. Table 49 gives the COP/BDM interface signals. The pin order shown reflects only the

COP/BDM connector order.

TRST

PORESET

Required assertion of TRST

Optional assertion of TRST

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