Freescale Semiconductor
Application Note
AN3555
Rev. 0, 11/2007
Contents
© Freescale Semiconductor, Inc., 2007. All rights reserved.
1 Introduction
The XGATE peripheral coprocessor includes a safety
feature called Software Error Detection. The Software
Error Detection feature lets the XGATE detect
conditions which should not occur during program
execution. The detection of these conditions indicate that
there are problems in the application code.
Whenever XGATE detects a Software Error Condition, it
ceases program execution immediately and flags an
interrupt to the CPU12X to perform corrective action. In
a typical application this corrective action simply
consists of initialization and system restart. However
during the development and debug phase of application
code it is desirable to know the exact cause of XGATE
Software Errors.
This document helps you investigate XGATE Software
Errors on S12X devices
1
. The S12XE (and S12XF)
1. Appendix A.1 provides a list of relevant S12X MCUs
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 The Software Error Detection Feature. . . . . . . . . . . . . . . 2
2.1 Software Error Conditions . . . . . . . . . . . . . . . . . . . . 2
2.2 Software Error Interrupts . . . . . . . . . . . . . . . . . . . . . 4
2.3 Software Error State . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Debugging Goal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Investigating Software Errors . . . . . . . . . . . . . . . . . . . . . 5
4.1 Sources of Information . . . . . . . . . . . . . . . . . . . . . . 5
4.2 Memory Protection . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.3 Observable Conditions . . . . . . . . . . . . . . . . . . . . . . 8
4.4 Software Error Scenarios . . . . . . . . . . . . . . . . . . . 10
4.5 Finding the Cause of a Software Error . . . . . . . . . 20
4.6 Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
A.1 List of S12X MCUs . . . . . . . . . . . . . . . . . . . . . . . . 30
Investigating XGATE Software
Errors
XGATEV2 (S12X) Software Error Debugging Aid
by: Dirk Heisswolf
MCD Design
Munich, Germany
