82551IT Datasheet, PDF (77/102 Pages) Intel Corporation – Fast Ethernet PCI Controller

Networking Silicon — 82551IT
10.0 82551IT Test Port Functionality
10.1
10.2
10.2.1
Introduction
The 82551IT’s XOR Tree Test Access Port (TAP) is the access point for test data to and from the
device. The port provides the ability to perform basic production level testing.
Test Function Description
The 82551IT TAP mode supports two tests that can be used in board level design. These tests help
verify basic functionality as well as test the integrity of solder connection on the board. The tests
are described in the following subsections.
Tristate
The tristate command sets all 82551IT input and output pins into a tristate (high-Z) mode (all
internal pull-ups and pull-downs are disabled). This mode is entered by setting the following test
pin combination and resetting the device:
TEST = 1
TEXEC = 0
TCK = 0
TI = 1
Datasheet
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