Linker Command File

[sebasira]

Hello!

I'm used to work with .prm file to define segments. But now I'm working with MCF51QE, since it's a ColdFire MCU, it has no longer a .prm files instead it's got a .lcf file.

I can't understand it....

If some could explain me it would be great because I'd like to learn about it. If you don't want to waste time explaining I just need to know how to define a new FLASH segment.

 What I want to do is save data into this new FLASH segment. I'm using routines from  AN3942SW. I want this segment to be 1024bytes long.

And one more question... I just want to be sure about this: When erasing flash, it is erased by blocks of 512bytes, right? 

Thanks!!!! Best Regards! 

[sebasira]

I forgot to say that I've allready read FAQ-27860

And I still can't work it out  

[CrasyCat]

Hello

Please use separate posts when you have different questions,

Some people may only have answer to one question and will not answer a post where you encapsulate multiple questions.

On .lcf file syntax, you can find some documentation on linker file syntax in {Install\MCU\Help|PDF\MCU_ColdFire_Compiler.pdf in chapter ELF Linker and Command Language.

Basically you define a new flash area by adding a new line in the MEMORY block.

For example:

MEMORY {   ...    my_flah (RX) : ORIGIN = 0x20000000, LENGTH = 0x00020000 } 

 This defines a block of memory starting at address 0x20000000 and which has a length of 0x20000 bytes.

Then you can place some sections in that segment in the SECTIONS block.

SECTIONS {  ...  .myCode : {} > my_flash }

CrasyCat

[sebasira]

Thanks for your replay CrasyCat.

Sorry about the other question, I was thinking about that and didn't realize that it's got nothing to do with the post.

I thought it would be "harder" to define a new section, because in the .lcf file, inside each section there are many things I don't understand. I'll try what you say and if I find another question, I'll let you know.

Thanks again!

[sebasira]

Here am I again!

Well, I still couldn't accomplish what I want to do.

All I want is to define a segment in FLASH where I can store constant data.

This is what I've done:

MEMORY {   myflash     (RX)  : ORIGIN = 0x00000410, LENGTH = 0x00000400   code        (RX)  : ORIGIN = 0x00000810, LENGTH = 0x00007AF0   userram     (RWX) : ORIGIN = 0x00800000, LENGTH = 0x00002000}SECTIONS {  .userram        : {} > userram  .code     : {} > code  .myDATA : {} > myflash

 Then I want a constant named const1 inside .myDATA and I do this:

#pragma CONST_SEG myDATA  const word const1;#pragma CONST_SEG DEFAULT 

But const1 appears at and address in RAM. Why's that???

The only way I managed to put it in flash is by setting its address as:

#pragma CONST_SEG myDATA  const word const1 @0x00000410;#pragma CONST_SEG DEFAULT 

Thanks a lot in advance!!!!

[CrasyCat]

Hello

    First if you are defining a constant you better define it with an initialization value.

   Otherwise the compiler does not consider it is a constant.

  Then using following notation you can place the variable in  user defined section named myData:

#pragma define_section myDataSec "myData" far_absolute R__declspec(myDataSec) const word const1 =6;

Then you should get the constant const1 allocated in section myData.

CrasyCat

[sebasira]

Well after a loooooot of reading and breaking my head against the wall with trial and error, I've manage to accomplish my task.

this post was very very useful!!!

[sebasira]

Thanks for your reply CrasyCat!

Well, I couldn't still make it work.... I guess I may be missing something.

I'll explain a little more what I want to do. Please, excuse my english. I've got an application that needs to store some data in FLASH, I'm working with MCF51QE96. As code is also in flash, I want to define an area where I will later store data, so I can erase it and not erase the code.

I went to the LCF file and found this:

MEMORY {   code        (RX)  : ORIGIN = 0x00000410, LENGTH = 0x00007AF0   userram     (RWX) : ORIGIN = 0x00800000, LENGTH = 0x00002000}
.... other stuff .....
  .userram        : {} > userram  .code     : {} > code

 This was my first time dealing with LCF. And I changed it to be like this:

MEMORY {   myflash     (RX)  : ORIGIN = 0x00000410, LENGTH = 0x00000400   code        (RX)  : ORIGIN = 0x00000810, LENGTH = 0x00007AF0   userram     (RWX) : ORIGIN = 0x00800000, LENGTH = 0x00002000}
.... other stuff ....  .userram        : {} > userram  .code     : {} > code  .myDATA : {} > myflash

 I've not idea if this is right... What I ment to do is define a new memory section called "myDATA" wich starts at address 0x410 and it contains 0x400 bytes (two FLASH blocks of 512bytes)

then inside one of my files I did as you said:

#pragma define_section myDataSec "myflash" far_absolute R__declspec(myDataSec) const dword FLASH_CODE = 0xFFFFFFFF;

And I found 2 things:

1- on .xMAP files FLASH_CODE does not appear (it is used in several parts of my code)

2- when debugging FLASH_CODE appears at address 0x00

Further infromation, all I want to do is erase/write flash area so I can store data using burst_prog and page_erase routines.

As I said before, the strange thing is that if I define as:

const dword FLASH_CODE @0x410;

I can perfectly used burst_prog and page_erase. Then go to address 0x410 (in debugger) and data is written. But if I enter "FLASH_CODE" in the Data component, it appears as UNDEFINED. Also not appearing in .xMAP

But I don't want to used it this way because I've got to keep track of address and size, in order to not overlap with other constatns

Please, help!

[FridgeFreezer]

There is some info in this thread:

https://community.freescale.com/message/23661#23661

And also my experience here:

https://community.freescale.com/thread/90614