Accessing the Functions Provided in the MAXQ Utility ROM

Abstract

Because of the single cycle nature of the MAXQ microcontrollers, application software cannot read directly from code space. To alleviate this issue, all MAXQ utility ROMs include routines for accessing data and tables stored in the program space. In addition to these core functions, the ROM for each MAXQ variation may have routines specific to that part. Since these functions might be located anywhere within the ROM, and could move with each revision of a ROM, a standard technique was developed for accessing the routines. This article demonstrates the proper method of accessing these functions.