M0 in-line assembler moving from bootloader to main app

[DiBosco]

Folks,

I have a bootloader for an M0 which works without using interrupts. It works in that it loads the new app, the CRC in the new app matches and I then try and jump to 0x8004000.

In the past I have used a couple of different methods with M3/4 to boot to the app from bootloader dependent on what compiler/IDE I was using, but the M0 is slightly different due to how the vector table is not relocatable. So we've come up with a method to get round that and "all" I need to do is jump to 0x8004000.

I *think I need something like this:

void jump_to_normal_application(void)
{

 u32 jump_address;

 jump_address = *(volatile u32*) (MAIN_PROG_START_ADDRESS + 4);
 jump_to_application = (pFunction) jump_address;

 asm("ldr sp, =0x20002000");

 jump_to_application();

}

I'm getting the error:

Error: lo register required -- `ldr sp,=0x20002000'

I've searched this and although I can find many hits  I can't see anything vaguely relevant to my situation.

Also, I would like to make 0x20002000 on line 9 top be a #define or loading from a C variable

Can anyone help me with this please? __Set_MSP is not available to me due to the, errr, "individual" setup I am forced to use.

What is the way to do this and are any of my assumptions above even vaguely correct? Am using gcc.

[wegi01]

@DiBosco When I sometimes want to look to value I use my small function which convert data from R1 register to ASCII HEX string to buffer pointed in R0 register.
Declaration in C looks:

extern void my_htoa32(char * buf, uint32_t data);

 

But if you want invoke this from assembler you should to do:

 ldr r0, = 0x20000369 // for example a free area for use as buffer 11 bytes
 ldr r1, = 0x42408200 // value for tested
 BL my_htoa32
 lll:
 b lll // neverending loop

 

Function my_htoa32:

 .syntax unified
 .cpu cortex-m0
 .fpu softvfp
 .thumb

 .thumb_func
 .global my_htoa32
 .type my_htoa32, %function


 .text
//----------------

//======================================================
// HEX 32BIT value convert to string
//====================================
 // INPUT:
 // R0, = ; POINTER TO OUTPUT char DATA BUFFER
 // R1, = ; VALUE TO HEXADECIMAL CONVERT

 // output: no output, data in buffer are output
//=======================================================
//=========================
my_htoa32:

 MOV R3, 0x7830 // "0x"
 STRH R3, [R0] // STORE "0x" TO BUFFER
 MOVS R3, 2 // output data 2 bytes after start buffer
//--
LP01:
 LSRS R2, R1, #28 // R2 = OUR DATA TO STRING CONVERT 1 BYTE = NYBBLE 0..F
 LSLS R1, R1, #4 // R1 * 16 = R1 << 4
 ADDS R2, R2, #0x30 // CONVERT TO NUMBER
 CMP R2, #0x3A
 BCC LP01A // if data < than 0x3a don't add #7
 ADDS R2,R2, 0x07 // CONVER TO LETTER
LP01A:
 STRH R2, [R0, R3] // STRH store byte and zero terminated
 ADDS R3, R3, #1
 CMP R3, #10
 BNE LP01
//---
 BX LR
//=============================================================

 

The result you can observe in STM32 Link Utility or in Cube Programmer: