It is unbelievable that they are not able to provide a decent hardware development platform that can match Arduino in ease of use & documentation, that use decent production-grade components, that's supported for sale for > 10 years and that has a clear path to switch from dev board to own IC.
I suspect that STM and TI are of similar difficulty, but I've only seriously played with Atmel because of the Arduino dev board (and related ecosystem).
10 year guaranteed availability of the exact same part is not guaranteed, but there's a clear enough lifecycle policy and paying any attention, you'll have a chance to a make a final "lifetime" buy. (If have the luxury problem that you're selling so much product that a lifetime buy is impractical, the NRE for a redesign is probably manageable for your business.)
That last part alone stops most people from playing with ARM, because you're almost forced to get boards made. At least with AVR/PIC you can prototype most of the Atmegas on a breadboard. Obviously there's a limit to what you can do with an AVR, but you can do a lot with 20MHz.
This may be an ARM thing though. I found it much more difficult to find development documentation for Atmel's XMega platform, I didn't even look at the SAM chips.
TI's website is a rabbit hole though. Sometimes the datasheet is enough, other times you have to go to their weird Wiki which looks unfinished. Sometimes it's available for free, other times you have to log in to get the information. STM isn't much better.
It's a crying shame. ARM is more capable and often cheaper and lower power than going the 8-bit route, but it's a pain in the arse to get started.
In terms of layout though, there isn't much in it. There are datasheets from ST that tell you what the mandatory hookups/passives are. Everything else is more or less identical to any other microcontroller, though you may need to worry about speed.
The documentation for STM and TI is far, far below the standard of Atmel's, both officially and unofficially. It's more difficult to find information, there's a much smaller development community for beginners and the boards start in TQFP.
>That last part alone stops most people from playing with ARM, because you're almost forced to get boards made. At least with AVR/PIC you can prototype most of the Atmegas on a breadboard. Obviously there's a limit to what you can do with an AVR, but you can do a lot with 20MHz.
Isn't it why we have development/prototyping boards right? You can always develop/experiment your code in it and also develop your PCB in parallel. In this way when there are problems with your custom board you can always be sure of your code.
In my experience TI documentation is excellent but their software sometimes is over engineered especially TI-RTOS.
Personally I have worked on the STM32F series and I found the documentation good. Also if you want to read through the internals of the ARM architecture you will have to refer to the ARM manuals from ARM website.
The core problem why many startups get stuck with Raspberry Pi, Arduino and friends is exactly the "dev board" problem.
When building an MVP and I have the choice between a $20 Pi/Arduino/Pi Compute Board and a $1.000+ dev board, hell I'll choose the Pi option. Lots more support, especially because any combo of I/O and a Pi has been tried by someone else before in contrast to $weird_sensor+$weird_niche_devboard, and especially you will want about 10 or more units so you can afford to blow a couple boards. This will happen inevitably during development, either by "fat fingering" +12V to a 3V3 input or by blowing the wrong eFuse, and better to lose 20$ than 1k$, not to mention you have to raise the 10k first...
It's not fun figuring out a board with no documentation and shit tools that noone ever used.
It doesn't justify why they make it so hard to set an IO pin or to load a program on their chips.