HP E3491A, Installation And Service Manual

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Designing a Target System
This chapter will help you design a target system that will work with
the HP E3491A Pentium Probe.
Designing a target system for use with the HP E2457A
Preprocessor Interface
The following should be considered when designing a target system for use
with the HP E3491A via the HP E2457A Pentium Preprocessor:
•
The TCK, TDI, TMS, TDO, TRST#, R/S# and PRDY target system signals
should not require more than 3 ma. at 2.4V or more than 4 ma. at 0.5V.
Excessive trace lengths on these signals should be avoided.
•
Target system circuitry should not actively drive TCK, TDI, TMS, TRST or
R/S#.
If necessary, all of the signals above can be disconnected from the
target system by removing the following pins from one of the pin
protectors on the bottom of the E2457A Pentium Preprocessor.
TCK (pin M34), TMS (pin P34), TDI (pin N35), TDO (pin N33),
TRST# (pin Q33), R/S# (pin AC35), PRDY (pin AC05)
•
To enable the E3491A Pentium Probe to reset the target system, an input
to the target system reset circuitry must be provided. This can be
connected to the target system by the 2-conductor cable assembly
(HP part number 64762-61602). A high true reset is available
from J3 of the HP E2457A. J3 can source 3 ma at 2.4 v and sink 4 ma at
0.5V. A low true reset is available from J6 of the HP E2457A. J3 can
source 3 ma at 2.4V and can sink 64 ma at 0.55V.
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