How to Use a Variable in SRAM to Communicate between Bootloader and Application

Chao · ‎2024-09-05

Hi,

I have a bootloader for my application, at the moment they exchange their working status by flash write. I think a better way is to declare a variable in RAM with the same address in both bootloader and application. Someone mentioned, in a post, that the linker script could be used for this, but didn't give an example.

Anybody could do me a favour and show me an example ? Thanks.

Chao · ‎2024-09-09

Using the first 4 bytes is a very nice solution. The last question is: does the SRAM start at 0x20000000 for all STM32 MCUs ?

SofLit · ‎2024-09-09

For the SRAMs used for data they start at 0x20000000. This is basically linked to the ARM specification and performance: need to refer to Cortex-Mx TRMs.

Example from Cortex M3 trm:

But some other SRAMs start at 0x0 for example ITCM (Tightly Coupled Memory) for F7 and H7 families. In any case, you need to check each STM32 part number datasheet.

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