stm32_programming VS CMSIS_5

The first thing you want to do is to get a JTAG adapter (I use ft2232h based board) and familiarize yourself with openocd. I have a tutorial on setting up openocd with ARM based chip. Then, you should get familiar with linker scripts.

Here's a repo I've made for my students https://gitlab.com/matsievskiysv/stm32_programming/. In it I start with assembly, introduce C and linker scripts and finally write my own HAL. It uses stock gcc, gdb and openocd from debian repo.

https://github.com/ARM-software/CMSIS_5/blob/develop/CMSIS/RTOS2/Source/os_systick.c bzw. dort https://www.keil.com/pack/doc/CMSIS/RTOS2/html/misraCompliance5.html#MISRA_1.

You can download the generic CMSIS files from here. The device-specific CMSIS header files can be downloaded from the Keil website: MDK5 Software Packs. Those pack files are ZIP files, btw.

CMSIS is Arm's own standard ("Cortex Microcontroller Software Interface Standard") for low-level software interfacing.

It's on Github [1], and rather nice. Vendor's middleware can be of varying quality, so just using CMSIS seems refreshingly nice!

[1] https://github.com/ARM-software/CMSIS_5

Sure, have a look at CMSIS-DAP, FreeDAP, Adafruit DAP, and Blackmagic Probe. SWD will let you access the target's memory space (e.g. RAM, registers, etc). To program the device, you will need to interact with the flash memory controller and this aspect is microcontroller-specific. You can tickle the flash controller registers manually (easier but slower) or you can use specialized RAM-code to make the microcontroller program itself (more difficult but faster).