stm32L496ZG dual boot

[ron23]

Posted on March 24, 2018 at 22:22

hi

im trying to implement dual boot using BFB2 bank switching on this chip, and after the code is burned in the second bank (ox80800000), it doesnt boot.

i single stepped through the bootloader code, and it seems that the bootloader checks the first bank address to be between 0x20000000 and 0x20040000, which fails because the initial SP is located near the end of SRAM which is at 0x20050000.for this chip.

could it be a bug in the bootloader code, or something im missing ? 

alternatively, how can i locate __init_sp in some lower address ?

[Tesla DeLorean · Accepted solution]

Posted on March 25, 2018 at 00:10

Just write a lower value in the first vector and load the SP with __init_sp in Reset_Handler

For GNU/GCC the stack is frequently defined in the .LD linker script.

...

; Vector Table Mapped to Address 0 at Reset

                AREA    RESET, DATA, READONLY                EXPORT  __Vectors                EXPORT  __Vectors_End                EXPORT  __Vectors_Size

__Vectors       DCD     0x20002000               ; Top of Stack - Nominal RAM address, set to __initial_sp later

                DCD     Reset_Handler              ; Reset Handler                DCD     NMI_Handler                ; NMI Handler                DCD     HardFault_Handler          ; Hard Fault Handler                DCD     MemManage_Handler          ; MPU Fault Handler

...

; Reset handler

Reset_Handler    PROC                 EXPORT  Reset_Handler             [WEAK]        IMPORT  SystemInit        IMPORT  __main

                 LDR     SP,=__initial_sp ;; Set SP, for Keil also done in __main as I recall

                 LDR     R0, =SystemInit

                 BLX     R0                 LDR     R0, =__main                 BX      R0                 ENDP

[ron23]

Posted on March 26, 2018 at 08:26

thanks, worked perfecly