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MSP430 software invoke BSL

Sy Tran
Intellectual 640 points

How do I jump to the BSL from the C code running on the target?

I am implementing feature to load in new code via software command which jumb to the BSL. I have read through the slaa452, slau319 but I could not decipher how to jump to the BLS. I tried to implement the  suggestion in slau319a, section 2.9.2 on page 20 using inline statement  --

asm("  BR  &0C00h); 

I tried to single step through the branch but it did not go to the location 0C00h but instead the PC = 3FFEh.  Do I need to set up access keys? Where do I find the example code that calls the BLS from C?  Thank you in advanced.

Regards,

Sy

  • 0
    Intellectual 640 points

    Enclosed is the simple code sequence that works

    /*---------------------------------------------------------------------------+
    | Invoke BSL to Load New Code
    | reference slaa452B May 2011, page 9, section 4.3
    +----------------------------------------------------------------------------*/
    void Flash_BSL(void)
    {
      // disconnect from USB so the BSL code can reconnect
      USB_disconnect();   // disconnect via disable PUR_EN
      
      __disable_interrupt();   // Disable global interrupts        
     
       //call to BSL Z-area and wait for the host application to download new code 
      ( (void (*)()) 0x1000)(); 
              
      // asm(" BR  &0C00h"); did not invoke the BSL as described in the app note slaa089d
    }

  • 0 in reply to Sy Tran
    Intellectual 435 points

    I did the exactly same thing, but it jumped back to the start of my application intead of BSL, what could I do wrong? Thanks!

  • 0 in reply to graviton
    Genius 3770 points

    Hi graviton,

    Which MSP430 are you using? If you have one with ROM-based BSL, the start vector is different than the flash BSL.

    Also depending on your debugger configuration, if you had checked "allow erase/write to BSL flash memory" you could have accidentally erased the flash BSL, in which case fetching from the vector would result in reset.

    Tony

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