Compiled code size and flashed code size are different in STM32CUBEIDE v1.15.1

Simo_Sappo · ‎2024-06-06

Hi everyone, I created an HID bootloader for the STM32G4xxx, it works and now I am trying to optimize the size. After compiling I can read this on the Build Analyzer a flash memory usage of 17.85 kB.

After compiling I get this:

When I flash this compiled code and read the flash memory I canclearly see that the memory usage is around 38 kB.

I also used the STM32CubeProgrammer to look at the actual memory (I didn't manage to use this function directly on STM32CubeIDE) and I can see that more than 38 kB are used in the memory

Can somebody explain why? Am I missing something about the Build Analyzer function?

Simo_Sappo · ‎2024-08-08

I found the problem, somehow even if I set the Release mode as active (with the size optimization) it was still flashing the Debug version of the code which is not optimized for size. I discovered this only after deleting the Debug and Release folders and staring the flashing process again. Thank you everyone for your help

View solution in original post

gbm · ‎2024-06-06

SREC file is a text file. It's size is a little over 2 times the programmed Flash footprint.

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice

Simo_Sappo · ‎2024-06-07

Thank you very much, is there a way to reduce its size or to flash into memory a different file that woul dbe smaller?

Andrew Neil · ‎2024-06-07

What's programmed into Flash is more than just the code - there's also all the data initialisation values.

The Build Analyser shows you exactly what's going into the Flash, and where:

Everything in the 'Load address' column is stored in Flash

.text is your executable code; some of the other things are mentioned here:

https://stackoverflow.com/questions/15265295/understanding-the-libc-init-array

Simo_Sappo · ‎2024-06-07

Okey so I understood what the build analyzer is showing. BUt where do the other 20 kB of code come from? Is there anyway to reduce this amount?

Andrew Neil · ‎2024-06-07

Show your Build Analyser output

Simo_Sappo · ‎2024-06-07

Sure, here it is

Andrew Neil · ‎2024-06-07

@Simo_Sappo wrote:

So you have 16.88KB of code, and a total of just 1092 bytes of extras.

That's pretty insignificant - only ~6% - so what are you worrying about?

Simo_Sappo · ‎2024-06-07

My problem is that the code I am actually flashing in the microcontroller is 38.37 kB, which I confirmed by also opening the flash memory with STM32CubeProgrammer. I don't understand why I am flashing a file that is double the size of my actual code.

Andrew Neil · ‎2024-06-07

But, as @gbm already said, that's the size of the SREC file on your hard drive - not the size of the data which gets programmed into the Flash?