Arduino for STM32

Howdy folks -

I'm a bit new to this.... Sorry.

I just finished a nasty little reverse engineering job on an AliExpress VR display driver board featuring the steadfast STM32F103C8T6, sometimes, or one of the clones. It was a terrible slog, but I got it, just in time to realize that perhaps, I could use a bit more program FLASH. Right now I'm at 91% full, no bootloader, and I want to be able to put serial numbers on the boards that I can read out later without having to resort to hard-coding ones in every time I compile. I know there's a 128KB version of this chip which is the obvious choice, but of course, they're impossible to buy, and what's more, some of the boards that I have feature clone CPUs which is not ideal, plus I'm not sure if pulling unique IDs from clones is even possible.

but I DO have a small number of STM32L4P5CET6 available, and they look pin-for-pin compatible. In the process of decoding this board I've reworked these original chips on and off the board several times, and have no qualms re-chipping them.

I don't see this particular chip in any of the lists. Is there some resource that I can look in to that would help me identify family compatibility / compile / core options for this chip? If there even are any? Am I mistaken that they're pin compatible?

Thanks team, and sorry for the nOOb questions.

based on the specs here
https://www.st.com/en/microcontrollers- ... 4p5ce.html
This chip is apparently in the Cortex M4, closer to the STM32F4 series.
But i think the L series has more functionalities in addition such as the low power features.

what it would likely take is to make a new variant
https://github.com/stm32duino/wiki/wiki ... 28board%29

Start with a chip/board that is closest to the STM32L4, copy that as a template and make a new variant.

For an existing board that has crystals and all in the right places, a main thing is to configure the system clock. i.e. the PLL dividers to get the system clock and pheriperial clocks running at the correct speeds.
https://github.com/stm32duino/wiki/wiki ... figuration
This is normally where 'newbies' stumble, rather often once this is correct, one would be able to try simple things like try to blink a led.

oh and this thread is posted in the 'wrong' section, it is better to 'move' it in the main general section or the official core section.
For an easier start, get a Nucleo board on the supported boards list
https://github.com/stm32duino/Arduino_Core_STM32

and F4 / L4 and stm32 F103 has quite different hardware, do be wary of the differences, check the manuals and specs, it may not necessary work by simply replacing it.