CC2642R: Want to allocate a variable in the flash after the flash usage by the firmware

I would also like to know how in the application firmware like simple_peripheral, I can access the last byte memory address from where the application firmware is ended?

Hi again,

(Sorry I missed your second message)

Mehul Dalal said:

I would also like to know how in the application firmware like simple_peripheral, I can access the last byte memory address from where the application firmware is ended?

It will depend what you want to do...

As I said before, the last Flash page contains the CCFG. You have ways to read the CCFG but I am not sure this is the sense of your question.

In a more generic way, you could declare a table and place it right before the CCFG (exactly like we discussed in our previous messages). That way you can access this table using its symbol.

Best regards,

Hi Clement,

Sorry for not clear enough. But we really do not have CCFG area defined in our application. Instead, the BIM defines it. It is similar to OAD project.

So, application linker file looks like this:

SECTIONS
{
  .intvecs        :   >  FLASH_START
  //FLASH_LAST_PAGE memory section is now use by the BIM Firmware and ccfg area
  //as FLASH_BIM_START and FLASH_CCFG_START (refer to the BIM linker file)
  //So, we can not use this memory for our Aplication Firmware code memory allocation
  .text           :   >> FLASH
  .const          :   >> FLASH
  .constdata      :   >> FLASH
  .rodata         :   >> FLASH
  .cinit          :   >  FLASH
  .pinit          :   >> FLASH
  .init_array     :   >  FLASH
  .emb_text       :   >> FLASH
  //for ccfg memory allocation refer to BIM linker file
  //.ccfg           :   >  FLASH_LAST_PAGE (HIGH)

  // Create a section for locating functions in RAM.
  // For example, the internal flash erase function (RamExecuteFlashSectorErase())
  .TI.ramfunc : {} load=FLASH, run=SRAM, table(BINIT)
  // Below section must be last
  .flash_usage_end  :   > FLASH

See the CCFG is not really defined in the application linker file. So, how I can get the end address of the flash application usage and place my variable there? Essentially, that variable is going to hold security specific data which must be at the end of the application firmware memory usage.

Clement, one more thing, Using memory before FLASH_LAST_PAGE is not an option as that will make the application firmware OAD image larger than the actual. As an example, let's say the application is of only 200KB but this variable will make application will make the application size near to 344 KB. That is not an option.

Hi,

Thank you for the details provided.

Given your requirements, I would suggest to force the linker to link the symbol at a specific address. That way you will be able to place the symbol exactly where you want. 

Here is a way to do this - you could of course use a define:

.flash_usage_end:   > 0x00023078

This leads to the following map file:

00022bce  cryptoMode                                                      
00022bcf  ecdhMode                                                        
00022bd0  __TI_static_base__                                              
00022fe8  __TI_Handler_Table_Base                                         
00022ff4  __TI_Handler_Table_Limit                                        
00023018  __TI_CINIT_Base                                                 
00023040  __TI_CINIT_Limit                                                
00023078  test_array                                                      
00057fa8  __ccfg                                                          
00058000  __UNUSED_FLASH_end__    

You can refer to this document for more information.

Best regards,

Hi Clement,

Having absolute value is not a correct solution. The application can expand its usage and we really cannot go every time and work on linker file to find the absolute value for the variable. There must be a way to get the variable to end without making change every single time (at least for other compiler like GHS, IAR have worked for).

Hi Clement,

Gentle reminder. Can you suggest?

Mehul

Hi Mehul,

I have asked linker experts to provide their inputs.

Please bear with me.

Regards,

Thanks for the update!

Hi,

If I understood this correctly, I think that you want to place the test_vector at the end of all the allocated code. In this case, can you check the e2e thread below that contains a good discussion about this?

https://e2e.ti.com/support/tools/code-composer-studio-group/ccs/f/code-composer-studio-forum/491556/how-to-explicitly-place-input-section-at-the-end-of-output-section-without-generating-warning

Hope this helps,

Rafael

I will take a look into this thread. However, by going through it quickly, this is not what I wanted. I do want to get the location of my application flash usage and have that address known to my application. I do not know what do you mean by test_vector (its not a vector table, it is just a variable I want to have after the allocated usage).

As I said, is there anyway in my application, I can know the end address of the application flash usage? That will work for me as well.

Hi Rafael, I have looked into the thread in detail and I believe that it is not explaining the resolution as what I wanted.

HI Clement, can I get a way to get the used flash in the application at runtime? That will also suffice my work. I have posted new e2e thread on this:

https://e2e.ti.com/support/wireless-connectivity/bluetooth-group/bluetooth/f/bluetooth-forum/1007279/cc2642r-how-to-get-application-flash-usage-in-the-application-fimrware

Kindly let know the solution.

Mehul