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run function from RAM

Marius Raducanu
Intellectual 680 points
Other Parts Discussed in Thread: CONTROLSUITE

I am trying to run a function out of RAM (time_1s_tick). I followed all the recommended steps presented in SPRA958K but the microcontroller (28069) goes in the Illegal interrupt when calling the function I placed in RAM.

Please help me.

 

This is what I done:
//in F28069.cmd:
ramfuncs        : LOAD = FLASHD,
                         RUN = RAML0,
                         LOAD_START(_RamfuncsLoadStart),
                         LOAD_END(_RamfuncsLoadEnd),
                         RUN_START(_RamfuncsRunStart),
                         LOAD_SIZE(_RamfuncsLoadSize),
                         PAGE = 0
.........................................................................................................................................................
//in my programs:
extern Uint16 RamfuncsLoadStart;
extern Uint16 RamfuncsLoadEnd;
extern Uint16 RamfuncsRunStart;
extern Uint16 RamfuncsLoadSize;
............................................................................................................................................................
         #ifdef FLASH
         // Copy time critical code and Flash setup code to RAM
         // The  RamfuncsLoadStart, RamfuncsLoadEnd, and RamfuncsRunStart
         // symbols are created by the linker. Refer to the linker files.
              //MemCopy(&RamfuncsLoadStart, &RamfuncsLoadEnd, &RamfuncsRunStart);
              memcopy(&RamfuncsRunStart, &RamfuncsLoadStart, &RamfuncsLoadSize);

 

         // Call Flash Initialization to setup flash waitstates
         // This function must reside in RAM
              InitFlash();  // Call the flash wrapper init function
         #endif //(FLASH)

 ....................................................................................................................................................................................

#pragma CODE_SECTION(time_1s_tick, "ramfuncs");
void time_1s_tick(void)
{
       second++;
       //LED2_BLINK;
       if(second==60)
       {
              second=0;
              minute++;
              if(minute==60)
              {
                     minute=0;
                     hour++;
                     if(hour==24)
                     {
                           hour=0;
                           day++;
                     }
              }
       }
       LED1_BLINK;
}

 

 

  • 0
    Intellectual 680 points

    Because I didn't get an answer to my question so far I continued to investigate the problem and this is what I found:

    My RAM function doesn’t return at the end. It looks that the code continues, I suppose, to run the next code/function in RAM (that is DSP28x_usDelay). When this function (DSP28x_usDelay) tries to return it goes at “0x8036” (No source available for "0x8036") and trigger the Illegal interrupt. So far, I have no explanation for this behavior.

    I had similar problems when calling InitAdc function. I found a few topics in this forum about this problem but not a good answer for me. It seems that the InitAdc uses DELAY_US that is a define using the in line DSP28x_usDelay  RAM function (it has to be in RAM because it’s used by InitFlash). I solved the problem replacing DELAY_US function with a simple for (for(i=0;i<10000;i++) {}).

    Any clue/solution for my problem running a function from RAM is welcomed.

    Thanks

  • 0 in reply to Marius Raducanu
    TI__Guru* 91135 points

    Marius,

    I suspect something is using a function allocated in ramfuncs before the copy.  Can you try putting the copy is the very first thing in your main() and see if that changes the behavior?

    -Lori

  • 0 in reply to Lori Heustess
    Intellectual 680 points

    Lori,

    Thanks for your answer.

    The main function starts with initializing the flash where the RAM functions are copied from flash to RAM. I read all the documentation a few times and I still cannot find the problem. It is very strange because using the debugger I found that my RAM function doesn’t return and continues with DSP28x_usDelay, also in RAM. When DSP28x_usDelay tries to return (to a not available address because it wasn’t called) the Illegal interrupt is triggered.  

     Regards,
    Marius   
  • 0 in reply to Marius Raducanu
    TI__Guru* 91135 points

    Marius Raducanu said:
    The main function starts with initializing the flash

    InitFlash() is part of the ramfuncs.  Make sure the copy is before the init of the flash.

    Marius Raducanu said:
    my RAM function doesn’t return

    Double check the .map file and make sure the function is truly allocated to RAM. 

    It really sounds like the copy isn't happening - if you examine the disassembly does it look like a legitimate function? or a bunch of random instructions?

    -Lori

  • 0 in reply to Lori Heustess
    Intellectual 680 points

    Lori,

    It works!

    I never debugged the part of the program with copying RAM function and initialization of flash because I implicitly supposed that it works because I was able to run my program from flash. Also, there is the note above this section: “// Note that the variable FLASH is defined by the compiler with -d FLASH”.

    It looks that was misleading because FLASH is not defined by the compiler (although I use F28069.cmd). After I defined: #define FLASH 1, everything works now.

    Questions: Why FLASH wasn’t defined by compiler? Is something that I have to do for this?

    Thanks,
    Marius
  • 0 in reply to Marius Raducanu
    TI__Guru* 91135 points

    Marius Raducanu said:

    Also, there is the note above this section: “// Note that the variable FLASH is defined by the compiler with -d FLASH”.

    It looks that was misleading because FLASH is not defined by the compiler (although I use F28069.cmd). After I defined: #define FLASH 1, everything works now.

    Marius,

    I agree the wording of the comment is a little confusing.  It means you can define it with the compiler by using the -d switch.  In the project properties there is a "predefined symbols" option which will add -d <symbol> that you specify.  In our flash projects we define the symbol in this manner.   Using #define works as well.

    Cheers

    Lori

  • 0 in reply to Lori Heustess
    Prodigy 10 points

    The idea of running time critical functions in RAM is so important to execution speed and battery life, it should be worth an app note or even a whitepaper, i would think.

    Are there any examples for c28335 delfino or the like.

    Thanks

    <N/M>

  • 0 in reply to Norman Mainwaring
    TI__Guru* 91135 points

    Norman Mainwaring said:

    The idea of running time critical functions in RAM is so important to execution speed and battery life, it should be worth an app note or even a whitepaper, i would think.

    Are there any examples for c28335 delfino or the like.

    Thanks

    <N/M>

    Hi Norman,

    A few ideas:

    • This application note has a section on copying sections from flash to RAM.  I think it is a great resource for understanding how code is allocated and can be moved from a load address in flash to a run address in RAM. www.ti.com/lit/SPRA958
    • In controlSUITE (www.ti.com/controlSUITE) there is a simple project for F2833x that copies some of the ISR routines from flash to execute in RAM.

    C:\ti\controlSUITE\device_support\f2833x\v133\DSP2833x_examples_ccsv4\flash_f28335

    Let me know if that helps. 

    Cheers

    Lori

  • 0 in reply to Lori Heustess
    Intellectual 350 points

    It could still be related to DELAY_US.  I put the memcpy immediately after (or as near as possible) InitSysCtrl() call and before InitPll() and InitAdc().

    One minor change to the memcopy code (to accomodate changes to the code):

        if (RamfuncsLoadSize != 0)
        {
            memcpy(&RamfuncsRunStart, &RamfuncsLoadStart, (Uint32)&RamfuncsLoadSize);
        }