MPC5121E datasheet(78/86 Pages) FREESCALE

78 / 86 page

MPC5121E/MPC5123 Data Sheet, Rev. 4

System Design Information

Freescale Semiconductor

4.4.2

Pull-Up Requirements for the PCI Control Lines

PCI control signals always require pull-up resistors on the motherboard (not the expansion board) to ensure that they contain

stable values when no agent is actively driving the bus. This includes PCI_FRAME, PCI_TRDY, PCI_IRDY, PCI_DEVSEL,

PCI_STOP, PCI_SERR, PCI_PERR, and PCI_REQ.

Refer to the PCI Local Bus specification.

4.5

JTAG

The MPC5121e/MPC5123 provides you with 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 MPC5121e/MPC5123’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.

4.5.1

TRST

Boundary scan testing is enabled through the JTAG interface signals. The 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 TRST signal must be asserted during power-on reset.

4.5.1.1

TRST and PORESET

The JTAG interface can control the direction of the MPC5121e/MPC5123 I/O pads via the boundary scan chain. The JTAG

module must be reset before the MPC5121e/MPC5123 comes out of power-on reset; do this by asserting TRST before

PORESET is released.

For more details refer to the Reset and JTAG Timing Specification.

Figure 61. PORESET vs. TRST

4.5.2

e300 COP/BDM Interface

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

4.5.2.1

Boards Interfacing the JTAG Port via a COP Connector

The MPC5121e/MPC5123 functional pin interface and internal logic provides access to the embedded e300 processor core

through the Freescale standard COP/BDM interface. Table 52 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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