Hcs12

CHANGE THE FUTURE

Working with the S12 Family and CodeWarrior Tips and Tricks Cesar Manzanarez
TIC México
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1Introduction
What is this training about ?

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Agenda
S12 Family Overview Memory map Linker Parameter File Remaping memory resources Map File Memory models EEPROM Module Review Break Optimizing calling conventions by hand Running routines in RAM Running routines from the Stack Mixing C and Assembly code Linking libraries EEPROM Interaction

Understanding memory architecture

Hands on/Codeexamples

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S12 Programmer Model Reminder

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S12 Programming Model

Used for branch conditions. Determinesto the next instruction tocontentsThean index used to Points operandsand result ofThe be executed Hold to the last used location of the stack of stack is Points Indexed Addressing. operations register are added and temporary data mask (Stores processor flags constants interruptcontent bit) save system contextto and the or to thestorage. of an accumulator to form the effective address of the instruction operand.

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Quick reminder of addressing modes
Inherent Immediate Direct No address needed Address supplied as operand Operand in the first 8-bit address space (zero page addressing) Operand in the 16-bit address space Address supplied as offsetfrom the current PC value Address supplied as offset from IndexRegister INX LDAA #$55 LDAA $55 LDAA $F03B JSR 7,PC STAB –8,Y

Extended Relative Indexed

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Instruction set efficiencyExample of instruction

Number of bytes taken by the instruction

Each letter here indicates one CPU cycle

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S12 Internal Resources

All of these resources need to be accessed usingI/O Registers a 16-bit address and a paging convention.

Example : S12D Family

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How to address all these resources with 16 bit addresses?

I/O Registers

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Flash Memory Space

The Flash’ 512 K are divided into 32 pages of 16K.

PAGE 0x20

PAGE 0x21

...

PAGE 0x3E

PAGE 0x3F

Flash pages are numbered and the last page is number 3F

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Flash Memory space
0x0000

Where does this fit in the 64K memory map?
0x4000

These pages are mirrored to the 0x8000-0xBFFF Memory range.

0x8000

PAGE 0x20 0xC000

PAGE 0x21

......