IEEE standard test access port and boundary-scan ...

1 The Institute of Electrical and Electronics Engineers, Park Avenue, New York, NY 10016-5997, USAC opyright 2001 by the Institute of Electrical and Electronics Engineers, rights reserved. Published 23 July 2001. Printed in the United States of : ISBN 0-7381-2944-5 SH94949 PDF: ISBN 0-7381-2945-3 SS94949No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the Std (Revision of IEEE Std )IEEE standard Test access Port and boundary-scan ArchitectureSponsorTest Technology Standards Committeeof theIEEE Computer SocietyApproved 14 June 2001 IEEE-SA Standards BoardAbstract.

2 Circuitry that may be built into an integrated circuit to assist in the test, maintenance, andsupport of assembled printed circuit boards is defined. The circuitry includes a standard interfacethrough which instructions and test data are communicated. A set of test features is defined,including a boundary-scan register, such that the component is able to respond to a minimum setof instructions designed to assist with testing of assembled printed circuit boards. Also, a languageis defined that allows rigorous description of the component-specific aspects of such : boundary scan, boundary-scan architecture, boundary-scan Description Language, boundary-scan register, BSDL, circuit boards, circuitry, integrated circuit, printed circuit boards,TAP, test, test access port, VHDL, VHSIC Hardware Description LanguageIEEE Standards documents are developed within the IEEE Societies and the Standards Coordinating Committees of theIEEE Standards Association (IEEE-SA) Standards Board.

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9 The IEEE shall not be responsible for identifying patentsfor which a license may be required by an IEEE standard or for conducting inquiries into the legal validity orscope of those patents that are brought to its 2001 IEEE. All rights (This introduction is not part of IEEE Std , standard Test access Port and boundary-scan Architecture.)This standard defines a test access port and boundary-scan architecture for digital integrated circuits and forthe digital portions of mixed analog/digital integrated circuits. The facilities defined by the standard seek toprovide a solution to the problem of testing assembled printed circuit boards and other products based onhighly complex digital integrated circuits and high-density surface-mounting assembly techniques.

10 Theyalso provide a means of accessing and controlling design-for-test features built into the digital integrated cir-cuits themselves. Such features might, for example, include internal scan paths and self-test functions aswell as other features intended to support service applications in the assembled of the development of this standardThe process of developing this standard began in 1985, when the Joint European Test Action Group(JETAG) was formed in Europe. During 1986, this group expanded to include members from both Europeand North America and, as a result, was renamed the Joint Test Action Group (JTAG).