2 Online Debugging Method¶

2.1 Breakpoint Debugging Method¶

For crashes that occur in bootloader code, during system startup, or during wake-up from sleep, Jlink or the serial port may already be unavailable. Such crashes are often difficult to locate. You can add a breakpoint at a code location where you have confirmed the system has not crashed yet, and then connect online through SifliUsartServer or Jlink for online single-step execution to locate the issue. You can add a breakpoint at the very beginning of system reset:
The HCPU startup assembly code is drivers/cmsis/sf32lb55x/Templates/arm/startup_bf0_hcpu.S The LCPU startup assembly code is drivers/cmsis/sf32lb55x/Templates/arm/startup_bf0_lcpu.S
Remove the comment character ‘;’ from the first instruction in Reset_Handler so that it becomes B .

; Reset Handler
Reset_Handler   PROC
                EXPORT   Reset_Handler             [WEAK]
                IMPORT   SystemInit
                IMPORT   __main

                B        . ;//MCU复位后第一条指令执行的位置，添加断点

                LDR      R0, =__stack_limit
                MSR      MSPLIM, R0                          ; Non-secure version of MSPLIM is RAZ/WI

                LDR      R0, =SystemInit ;//对应c语言函数void SystemInit(void)
                BLX      R0
                LDR      R0, =__main ;//对应c语言函数int $Sub$$main(void)->rtthread_startup();
                BX       R0
                ENDP

In this way, when the MCU starts, it will stay at the first instruction. After Jlink connects successfully, you can use Ozone or keil to change the PC register (+2) and set the required breakpoints, so as to debug the initialization process.
You can also add the assembly instruction __asm("B ."); in the c file SystemInit() or rtthread_startup().

__ROM_USED int rtthread_startup(void)
{
    rt_hw_interrupt_disable();

    /* board level initialization
     * NOTE: please initialize heap inside board initialization.
     */
#ifdef RT_USING_PM
    rt_application_init_power_on_mode();
#endif // RT_USING_PM
    __asm("B ."); //设置断点
    rt_hw_board_init();

This keeps the system stopped at this instruction. At this time, connect J-Link, and use Ozone or Keil to change the PC register (+2), then continue single-step or breakpoint debugging.

2.2 Ozone Single-Step Debugging Configuration¶

Please refer to the relevant section for the Ozone tool:
4.3 Ozone Single-Step Debug

2.3 Keil Single-Step Debugging Configuration¶

alt text

Method for importing an axf file:

Import by command
Import by script file
Add the script file loadaxf.ini to the keil root directory, with the following content:

Note: The axf file bf0_ap.axf must be placed in the keil root directory; Add loadaxf.ini to the configuration interface;