Browse Prior Art Database

Testing Counters

IP.com Disclosure Number: IPCOM000083969D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 82K

Publishing Venue

IBM

Related People

Bodner, RE: AUTHOR [+2]

Abstract

This n-stage counter in an electronic circuit module is 100% testable at both the module and card level, with a minimum number of test patterns and minimum additional I/O pins. The module containing the counter includes logic in addition to the counter and is mounted on a card containing one or more other modules.

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Testing Counters

This n-stage counter in an electronic circuit module is 100% testable at both the module and card level, with a minimum number of test patterns and minimum additional I/O pins. The module containing the counter includes logic in addition to the counter and is mounted on a card containing one or more other modules.

The card and module relationship is schematically illustrated in Fig. 1. Card 10 is shown as including modules 15 and 20. Module 20 contains the n-stage counter 30 of Fig. 2. Counter 30 includes triggers 31, 32 and 33 where each trigger consists of the logic elements shown in Fig. 3. The -SET input of each trigger is commonly connected to an output from other logic in module block 40, Fig. 2, whereby triggers 31, 32 and 33 can be set to a predetermined state.

The clock input C of trigger 31 receives a clock signal from module 15. The clock inputs of triggers 32 and 33 are connected to the Q outputs of triggers 31 and 32, respectively. The Q outputs of triggers 31, 32 and 33 are connected to their respective data D inputs. The arrangement described so far enables counter 30 to operate in a normal binary mode.

Counter 30 can be tested through the facility of test inputs -T1 and +T2 and auxiliary data input AD. The auxiliary data inputs AD of triggers 31, %2 and 33 are connected to card/module I/O pins via lines A, C and F, respectively, and are used in a test mode by gating signal TEST 2. A TEST 1 gating signal is also used to facilitate the complete testing of the triggers.

The auxiliary data inputs AD, when properly activated, enable operation of counter 30 in a nonripple mode. This reduces the number of test patterns ...