PC7410 datasheet(47/54 Pages) ATMEL

47 / 54 page

PC7410

2141D–HIREL–02/04

Boundary scan testing is enabled through the JTAG interface signals. (BSDL descrip-

tion s

o f

the

PC74 10

are

av ailab l e

the

In tern et

www.mot.com/PowerPC/teksupport.) The TRST signal is optional in the IEEE 1149.1

specification but is provided on all PowerPC implementations. 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 dur-

ing power-on reset. Since the JTAG interface is also used for accessing the common

on-chip processor (COP) function of PowerPC processors, simply tying TRST to

HRESET is not practical.

The common on-chip processor (COP) function of PowerPC 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 con-

nects 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 32 allows the COP to independently assert HRESET

or TRST, while ensuring that the target can drive HRESET as well. The pull-down resis-

tor on TRST ensures that the JTAG scan chain is initialized during power-on if a JTAG

interface cable is not attached; if it is attached, it is responsible for driving TRST when

needed.

Table 20. COP Pin Definitions

Pins

Signal

Connection

Special Notes

1TDO

TDO

2QACK

QACK

Add 2K pull-down to ground. Must be merged with on-board QACK, if any.

3TDI

TDI

4TRST

TRST

Add 2K pull-down to ground. Must be merged with on-board TRST if any.

See Figure 32.

RUN/STOP

No Connect

Used on 604e; leave no-connect for all other processors.

VDD_SENSE

VDD

Add 2K pull-up to OVDD (for short circuit limiting protection only).

7TCK

TCK

CKSTP_IN

Optional. Add 10K pull-up to OVDD. Used on several emulator products. Useful for

checkstopping the processor from a logic analyzer of other external trigger.

9TMS

TMS

N/A

SRESET

Merge with on-board SRESET, if any.

N/A

HRESET

Merge with on-board HRESET.

N/A

Key location; pin should be removed.

CKSTP_OUT

Add 10K pull-up to OV

DD.

Ground

Digital Ground

PC7410 Datasheet(PDF) 47 Page - ATMEL Corporation

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