TM4C123 bootloader - jump to desired flash location and run app

Would it not ease your quest to employ vendor's bootloader examples (coded in C) and to observe the ASM code which results? And as a successful Bootloader example EXISTS - why would you invest time/effort to re-invent a (proven) wheel?

Forcing those here AWAY from vendor's API - or "normal C" - places extra strain upon vendor's (rare) and most valuable resource.

Beyond the above - you've provided no indication of your IDE, nor compiler - such (often) proves useful.

Hello Dileep,

Add a space between the starting quote and the ASM instruction as shown below

__asm(" ldr r1, [r0]\n"
" mov sp, r1\n");

Regards
Amit

Hi Amit,

Below is a piece of code which i took it from one of bootloader example and calling it once after writing bin file to flash. But still the application is not called. Please let me know where i am going wrong.

#define _APP_START_ADDRESS 0x2800
#define _VTABLE_START_ADDRESS 0x2800

__asm uint32_t
callApp(void)
{
//EnterApplication

mov lr, r9

/* ;
; Copy the application's vector table to the target address if necessary.
; Note that incorrect boot loader configuration could cause this to
; corrupt the code! Setting VTABLE_START_ADDRESS to 0x20000000 (the start
; of SRAM) is safe since this will use the same memory that the boot loader
; already uses for its vector table. Great care will have to be taken if
; other addresses are to be used.
;*/
if (_APP_START_ADDRESS != _VTABLE_START_ADDRESS)
movw r0, #(_VTABLE_START_ADDRESS & 0xffff)
if (_VTABLE_START_ADDRESS > 0xffff)
movt r0, #(_VTABLE_START_ADDRESS >> 16)
endif
movw r1, #(_APP_START_ADDRESS & 0xffff)
if (_APP_START_ADDRESS > 0xffff)
movt r1, #(_APP_START_ADDRESS >> 16)
endif

/* ;
; Calculate the end address of the vector table assuming that it has the
; maximum possible number of vectors. We don't know how many the app has
; populated so this is the safest approach though it may copy some non
; vector data if the app table is smaller than the maximum.
;*/
movw r2, #(70 * 4)
adds r2, r2, r0
VectorCopyLoop2
ldr r3, [r1], #4
str r3, [r0], #4
cmp r0, r2
blt VectorCopyLoop2
endif

/* ;
; Set the application's vector table start address. Typically this is the
; application start address but in some cases an application may relocate
; this so we can't assume that these two addresses are equal.
;*/
movw r0, #(_VTABLE_START_ADDRESS & 0xffff)
if (_VTABLE_START_ADDRESS > 0xffff)
movt r0, #(_VTABLE_START_ADDRESS >> 16)
endif
movw r1, #(NVIC_VTABLE & 0xffff)
movt r1, #(NVIC_VTABLE >> 16)
str r0, [r1]

/* ;
; Remove the NMI stack frame from the boot loader's stack.
;*/
ldmia sp, {r4-r11}

/* ;
; Get the application's stack pointer.
;*/
if (_APP_START_ADDRESS != _VTABLE_START_ADDRESS)
movw r0, #(_APP_START_ADDRESS & 0xffff)
if (_APP_START_ADDRESS > 0xffff)
movt r0, #(_APP_START_ADDRESS >> 16)
endif
endif
ldr sp, [r0, #0x00]

/* ;
; Fix up the NMI stack frame's return address to be the reset handler of
; the application.
;*/
ldr r10, [r0, #0x04]
bic r10, #0x00000001

/* ;
; Store the NMI stack frame onto the application's stack.
;*/
stmdb sp!, {r4-r11}

/* ;
; Branch to the application's NMI handler.
;*/
ldr r0, [r0, #0x08]
bx r0

}

Hello Dileep

Which example are you referring to?

Regards
Amit

Hi Amit,

My previous issue got solved, I had to disable the systick before jumping to application.

New issue:
Controller : TM4C123GH6PM
Application StartAddress : 0x2800

If Application size is 52004 bytes, bootloader writes to Flash but fails to start the application.
I have reduced application size to 51864 bytes, bootloader writes to flash and start the application also.

Don't know why the behavior is like this.

Regards,
Dileep

Hello Dileep,

That should not be the case. If the application+bootloader size is within 256K and the application is placed in the flash such that Total Flash Size - Boot Loader size > Application Size, then it should be able to flash and execute.

Regards
Amit