Logic circuits systems, and methods having individually testable logic modules

US5173904A · kind A · utility

Assignee

• TEXAS INSTRUMENTS INCORPORATED · US

Inventors

• Martin D. Daniels · Houston, US
• Derek Roskell · Wellingborough, GB

Key dates

• Filing date: Jun 17, 1991
• Grant date: Dec 22, 1992
• Expiry date: Jun 17, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R31/318558
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A modular logic circuit is disclosed, where each of the modules may be selected for testing by means of a scan path within the module made up of serial register latches (SRLs), each SRL being connected to predetermined nodes in the module functional circuitry. Each of the modules has a test port, which is independent from the system bus interconnections in the logic circuit, and which has an SRL for receiving serial data for selection of the scan path within the module. Responsive to the logic state stored in a module's selection SRL, the scan path within the module will either be enabled or disabled. After selection of a module or modules for testing, serial data is scanned into the SRLs in the scan path for setting the associated predetermined functional circuitry nodes; after exercise of the functional circuitry, the SRLs in the scan path store the results of the exercise at the predetermined nodes. An additional SRL is contained within each test port, and in the scan path, for storing a logic state corresponding to whether the functional circuitry in the module is to be connected to or disconnected from the system bus during the test sequence. A configuration is further disclos…