S12 / MagniV Microcontrollers中的主题 HCS12 + Fixed address for two functions

HCS12 + Fixed address for two functions

ssinfod — Tue, 24 Sep 2013 20:18:25 GMT

Hello, I am using a HCS12DP512 MCU and I have a question regarding the Complier/Linker.

I`m trying to allocate two functions to the same specific address.

Ideally, it would like to do something like:

void t1(void) @0x9000

{

putchar('1');

}

void t2(void) @0x9000

{

putchar('2');

}

By default, one of the function would be included in my program. Then at run time, the user could send just the S-Record for one of this function with the bootloader in my MCU.

That would be useful when there is not enough room in the FLASH (code page). I could use this feature to have unit testing or debugging function in the field.

How can I achieve this with CodeWarrior IDE for HCS12 ?

I know I can create a user segment in the PRM file but It seems the LINKER will place both functions one after the other.

I really want to force these two fonctions at one specifc address.

Is that possible ?

Thanks in advance for your answer.

ssinfod

Re: HCS12 + Fixed address for two functions

RadekS — Mon, 07 Oct 2013 13:03:33 GMT

I am afraid that I am not fully sure what you want to do with your code.

I suppose that you want call function at address 0x9000.

In default code you will use for example function “t1”.

I suppose that you additionally need compiled code of function “t2”. This function t2 will be loaded via bootloader. Correct?

I would like to recommend Conditional Assembly Directives:

For example:

//#define CHANGE

void t1(void) @0x9000

{

#ifdef CHANGE

putchar('2');

#else

putchar('1');

#endif

}

In first run CHANGE is not defined and t1 contains command putchar('1');.

When you define CHANGE and compile project again, t1 will contains command putchar('2');.

Function t1 stay at the same address, and you can change content of flash by bootloader.

As you already mentioned, I would like to recommend create user segment for this function and size of this segment should be divisble by flash sector size. Code placement:

#pragma CODE_SEG MY_ROM

void t1(void) @0x9000

{

...

}

#pragma CODE_SEG DEFAULT