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Freescale Semiconductor
Application Note
Document Number: AN2615
Rev. 4, 07/2007
Contents
© Freescale Semiconductor, Inc., 2006,2007. All rights reserved.
1 Introduction
The 9S12XDP512 MCU provides significant
performance improvements over the existing 9S12
family through a combination of increased clock speed
and enhanced functionality. Existing S12 users can take
advantage of the increased speed of operation of the
S12XD family almost immediately due to its very high
level of backwards compatibility. Further performance
benefits can be gained by optimizing the application
design to take advantage of the new feature set.
This document describes the notable differences between
the S12 family and the S12XD family. Developers
currently designing applications with the S12 family
should take note of these differences so they are well
placed to take advantage of the S12XD when
appropriate. A companion application note (AN3469)
describes the compatability between the S12 and the
S12XE families.
This document is structured in two sections. The first
section (S12XD Enhancements) describes the functional
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 S12XD Enhancements . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1 Software Architecture. . . . . . . . . . . . . . . . . . . . . . 2
2.2 CPU and Instruction Set. . . . . . . . . . . . . . . . . . . . 3
2.3 Interrupt Controller . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 XGATE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.5 Memory Management Controller . . . . . . . . . . . . 11
2.6 Expanded Bus interface. . . . . . . . . . . . . . . . . . . 13
2.7 Debug Module . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.8 Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.9 Enhanced Capture Timer. . . . . . . . . . . . . . . . . . 15
2.10 Real Time Interrupt . . . . . . . . . . . . . . . . . . . . . . 15
2.11 COP — Watchdog . . . . . . . . . . . . . . . . . . . . . . . 15
2.12 Periodic Interrupt Timer . . . . . . . . . . . . . . . . . . . 16
2.13 Miscellaneous Modules . . . . . . . . . . . . . . . . . . . 16
3 Considerations for Existing S12 Applications . . . . . . . . 18
3.1 General Comments . . . . . . . . . . . . . . . . . . . . . . 18
3.2 CPU and Instruction Set. . . . . . . . . . . . . . . . . . . 18
3.3 Interrupt Controller . . . . . . . . . . . . . . . . . . . . . . . 18
3.4 Memory Configuration and Access . . . . . . . . . . 19
3.5 Expanded Bus interface. . . . . . . . . . . . . . . . . . . 21
3.6 Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.7 TEST and Reset Pins. . . . . . . . . . . . . . . . . . . . . 22
3.8 Background Debug Module . . . . . . . . . . . . . . . . 22
3.9 Debug Module . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.10 Backwards Compatible Modules . . . . . . . . . . . . 23
3.11 Unchanged Modules . . . . . . . . . . . . . . . . . . . . . 24
S12 and S12XD Family
Compatibility
by: Steve McAslan, 8/16-bit Products Division, East Kilbride
Joachim Krücken, 8/16-bit Products Division, Munich
