The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 29, 2005
Filed:
Aug. 12, 2003
Wayne Edward Wennekamp, Rio Rancho, NM (US);
Eric E. Edwards, Albuquerque, NM (US);
Roy D. Darling, Albuquerque, NM (US);
Wayne Edward Wennekamp, Rio Rancho, NM (US);
Eric E. Edwards, Albuquerque, NM (US);
Roy D. Darling, Albuquerque, NM (US);
Xilinx, Inc., San Jose, CA (US);
Abstract
On-the-fly reconfiguration of a secured CPLD. In one embodiment, a CPLD includes a novel security circuit that provides two different security control signals: an EEPROM/SRAM security signal and an EEPROM security override signal. The EEPROM/SRAM security signal prevents reading from both the EEPROM and the SRAM, and also prevents writing to the EEPROM. The EEPROM security override signal enables reading and writing for the EEPROM even when otherwise disabled by the EEPROM/SRAM security signal, but is active only when a specific set of conditions are met. These conditions can include, for example, the application of a sufficiently long erase pulse to the EEPROM array. Thus, the security on the EEPROM array is overridden only after the configuration data set stored in the EEPROM array has been erased. Reading from the SRAM is not enabled by the EEPROM security override signal. Therefore, the configuration data set is not compromised.