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:
Jun. 13, 2000
Filed:
Aug. 25, 1997
Franklin Sai-Wai Ho, San Carlos, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A system and method for selecting a post-reset operating mode for a microcontroller. The system of this invention includes a mode indicating means to communicate to the microcontroller the desired post-reset operating mode. These means may include pin(s), and/or bit flags in main memory or register. A mode selection logic circuit receives the mode detector information. If the program code corresponding to the desired operating mode has a starting address in main memory different from the default starting address of the first fetch instruction to the CPU, then the mode selection logic disables the program memory to prevent the first instruction fetch by the CPU, and instead, inserts a surrogate branch instruction onto the data bus causing the CPU to BRANCH to the starting address of the program code corresponding to the desired post-reset operating mode. Re-enabling the program memory after insertion of the surrogate branch instruction permits the CPU to execute the appropriate program code to put the microcontroller in that desired operating mode.