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A METHOD TO PERFORM A MULTIPLEXED TEST MODE IN A MINIMAL PIN CONFIGURATION

IP.com Disclosure Number: IPCOM000007281D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2002-Mar-11
Document File: 4 page(s) / 263K

Publishing Venue

Motorola

Related People

Oded Vishay: AUTHOR [+3]

Abstract

The Motorola Modular Family (MMF) is currently composed of two groups of products; the MC68HC16 family, based on the CPU16 core, and the MC68HC300 family, based on the CPU32 core. Each product in the MMF contains a CPU module, a system integration module, and one or more of the other modules available in this family.

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MOTOROLA Technical Developments Volume 23 October 1994

A METHOD TO PERFORM A MULTIPLEXED TEST MODE IN A MINIMAL PIN CONFIGURATION

by Oded Vishay, Eric Hoang and Anthony Reipold

  The Motorola Modular Family (MMF) is currently composed of two groups of products; the MC68HC16 family, based on the CPU16 core, and the MC68HC300 family, based on the CPU32 core. Each product in the MMF contains a CPU module, a system integration module, and one or more of the other modules available in this family.

  For each of the modules in the Motorola Modu- lar Family, a large number of test patterns have been developed to produce a required fault coverage level. The cost to develop these test patterns was very high, and the time to write the patterns was very long-up to several years. These tests were written using a predetermined number of input and output pins, the number of which was determined at the time that the test patterns were developed.

  The fault grade of a module requires a netlist of the actual design, and a corresponding set of test patterns. The fault grade also requires a set of pins to stimulate the part (controllability), and a set of pins to monitor the device's operation (observability).

the modularity of the MME all production test pat- terns must be based only on the minimum pin set.

  As a System Integration Module, the GRIM pro- vides the External Bus Interface for all other mod- ules on the derivative. Since the GRIM handles the external bus interface, its timing affects the testing and the fault grading of all other modules on the device. Removing pins from a system integration module decreases the controllability and the observability of the device, and thus reduces the fault coverage. Lower fault coverage means more bad parts are shipped to our customers.

  In the current competitive marketplace, there is a need to maintain the quality of our parts without the added cost of developing additional test patterns, and without using methods which increase test time, and result in higher production cost.

BACKGROUND:

THE SOLUTION:

THE PROBLEM:

  In the past, when pins were removed from a device so that it would fit in a smaller package, it was required to redo the test patterns, to recover any lost fault coverage, or accept that loss. If new patterns were written, they too would have to be fault graded, thus increasing the test cost.

  The Greatly Reduced Integration Module, GRIM, is a new module in the Motorola Modular Family, designed to be used in small pin count pack- ages for decreased cost. To meet its goal, the GRIM introduced a minimum set of required pins. The minimum pin configuration is a subset of the pins which were used to develop test patterns for the var- ious modules in the Modular Family To maintain

0 Motorola, Inc. 1994

  The GRIM added a special test mode which allows all required signals to be driven internally, regardless of the availability of that signal as a pin
(i.e. pin may be unimplemented). This test mode al...