MPC7410 datasheet(40/56 Pages) FREESCALE

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MPC7410 RISC Microprocessor Hardware Specifications, Rev. 6.1

Freescale Semiconductor

System Design Information

the MPC7410 or by other receivers in the system. These signals can be pulled up through weak (10-k

Ω) pull-up

resistors by the system, address bus driven mode can be enabled (see the MPC7410 RISC Microprocessor Family

Users’ Manual for more information on this mode), or these signals may be otherwise driven by the system during

inactive periods of the bus to avoid this additional power draw. The snooped address and transfer attribute inputs

are: A[0:31], AP[0:3], TT[0:4], CI, WT, and GBL.

In systems where GBL is not connected and other devices may be asserting TS for a snoopable transaction while not

driving GBL to the processor, we recommend that a strong (1 k

Ω) pull-up resistor be used on GBL. Note that the

MPC7410 will only snoop transactions when GBL is asserted.

The data bus input receivers are normally turned off when no read operation is in progress and, therefore, do not

require pull-up resistors on the bus. Other data bus receivers in the system, however, may require pull-ups, or that

those signals be otherwise driven by the system during inactive periods by the system. The data bus signals are:

DH[0:31], DL[0:31], and DP[0:7].

If address or data parity is not used by the system, and the respective parity checking is disabled through HID0, the

input receivers for those pins are disabled, and those pins do not require pull-up resistors and should be left

unconnected by the system. If parity checking is disabled through HID0, and parity generation is not required by the

MPC7410 (note that the MPC7410 always generates parity), then all parity pins may be left unconnected by the

system.

The L2 interface does not normally require pull-up resistors.

8.7 JTAG Configuration Signals

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 PowerPC architecture. While it is possible

to force the TAP controller to the reset state using only the TCK and TMS signals, more reliable power-on reset

performance will be obtained if the TRST signal is asserted during power-on reset. Because the JTAG interface is

also used for accessing the common on-chip processor (COP) function, simply tying TRST to HRESET is not

practical.

The COP function of these processors allows a remote computer system (typically, a PC with dedicated hardware

and debugging software) to access and control the internal operations of the processor. The COP interface connects

primarily through the JTAG port of the processor, with some additional status monitoring signals. The COP port

requires the ability to independently assert HRESET or TRST in order to fully control the processor. If the target

system has independent reset sources, such as voltage monitors, watchdog timers, power supply failures, or

push-button switches, then the COP reset signals must be merged into these signals with logic.

The arrangement shown in Figure 25 allows the COP port to independently assert HRESET or TRST, while ensuring

that the target can drive HRESET as well. If the JTAG interface and COP header will not be used, TRST should be

tied to HRESET through a 0-

Ω isolation resistor so that it is asserted when the system reset signal (HRESET) is

asserted, ensuring that the JTAG scan chain is initialized during power-on. While Freescale recommends that the

COP header be designed into the system as shown in Figure 25, if this is not possible, the isolation resistor will allow

future access to TRST in the case where a JTAG interface may need to be wired onto the system in debug situations.

The COP header shown in Figure 25 adds many benefits—breakpoints, watchpoints, register and memory

examination/modification, and other standard debugger features are possible through this interface—and can be as

inexpensive as an unpopulated footprint for a header to be added when needed.

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