I am a newbie in embedded programming. My idea is to build 3 applications with 3 separate project file. These 3 applications will work together in 1 CPU as shown in the image below:
To jump from App to another APP, I do the same way bootloader jumps to application:
#define ADDR_APP_2_PROGRAM 0x08120000
#define ADDR_APP_3_PROGRAM 0x08140000
typedef void (*pJumpFunc)(void);
pJumpFunc Jump_To_App;
void Jum_To_APP_2(void);
int main(void)
{
Jum_To_APP_2();
}
void Jum_To_APP_2(void)
{
Jump_To_App = (pJumpFunc)*(volatile uint32_t*)(ADDR_APP_2_PROGRAM + 4);
// __disable_irq();
__set_MSP(*(volatile uint32_t*) ADDR_APP_2_PROGRAM);
Jump_To_App();
}
Jump from one application to another was successful. But the obvious problem here is that data segment initializers copy from flash to SRAM of APP_2 and APP_3 will be performed repeatedly in a loop. I thought of a few ideas like: skipping the copy instructions in the startup code from the 2nd loop onwards, but I'm stuck. I don't find any commands related to _sdata, _sidata... or bss in the startup file generated by STM32CubeMX. Is there some hidden code associated with the current startup file? Can I create a custom startup file to replace the current startup file?
If you can I would love for you to give me an idea! Thank you very much!
(I'm using Keil.I used the label STM32CubeIDE because I couldn't find a more suitable label.)
The default startup file generated by CubeMX initializes SRAM appropriately and uses the _sdata and similar variables. For example, here is an excerpt:
The startup file is typically named startup_stm32*.s
You can, of course, modify the startup file however you want as long as you do the necessary things inside of it.
Edit:
The _sdata and similar get defined in the linker file, which depend on the sections you define in there. Maybe that's what you're missing. You'll have to ensure the sections for each program do not overlap at all, then it should just work.
Seems a whole lot easier to make one program rather than 3. But the scheme is certainly doable.
