jump to application code in bootloader code

Hello,
as in "Cortex™-M4 Devices Generic User Guide" (ARM DUI 0553A):
on system reset, the vector table is fixed at address 0x00000000. Privileged software can write to
the VTOR to relocate the vector table start address to a different memory location.
A good (in my opinion) starting point is in "Stellaris® Boot Loader USER’S GUIDE",
(TI document SW-BOOTLDR-UG-8555).

To branch to the application :
- Set the vector table to the beginning of the app
- Load the stack pointer from the application's vector table
- Load the initial PC from the application's vector table and branch to
  the application's entry point.

 as in the  Stellarisware bootLoader example, "bl_startup_ewarm.S"
 
 Finally, see also posts

http://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/t/317657.aspx

http://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/t/300316.aspx
 
 Regards,
 Claudio
 

Hi

Can somebody  explain me specifically what changes needs to be done to make this boot loader run and jump to the application for execution? Can i have a small example for that or sequence of steps required ?

Thanx in advance !!

Hi,

here is an excerpt from TivaWare callApplication() function.

  // Set the vector table to the beginning of the app in flash.
    HWREG(NVIC_VTABLE) = ui32StartAddr;
	
    // Load the stack pointer from the application's vector table.
    //
    __asm("    ldr     r1, [r0]\n"
          "    mov     sp, r1");

    // Load the initial PC from the application's vector table and branch to
    // the application's entry point.
    //
    __asm("    ldr     r0, [r0, #4]\n"
          "    bx      r0\n");

Hope it helps.

Regards,

Claudio