F CPU FUNCTIONAL PROBLEMS

This appendix contains the following sections:

Introduction
CPU Functional Problem Bypasses

1 Introduction

Several chip suppliers publish microcontroller errata sheets for reporting both functional problems and deviations from the electrical and timing specifications.

For some of these functional problems in the microcontroller itself, TASKING's 8051 C compiler and/or assembler can provide workarounds. In fact these are software workarounds for hardware problems.

This appendix lists a summary of functional problems which can be bypassed by the compiler tool kit.

Please refer to the chip supplier's errata sheets to verify if you need to use one of these bypasses.

2 CPU Functional Problem Bypasses

Generate NOP instruction before DIV AB instruction

Dallas reference: Dallas DS80C390 erratum #6, revision B3 01/19/00

Use compiler option:

or use assembler control:

When you use the Dallas DS80C390 derivative, the DIV AB instruction may return erroneous results if the A register is accessed immediately preceding the DIV AB instruction.

With the compiler option -bp1 (or the assembler control BYPASS(1)) an extra NOP is inserted before any DIV AB instruction.


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