I think that's what AVR is; there is a clear (and reasonably straightforward) path from Arduino to production on a custom board. I'm a total hack/n00b and my first AVR PCB worked.
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.)
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.
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.
You can always get MSP430 Launchpads at $9.99 which comes with a MSP430G2x in a DIP. You can breadboard it if you want or you can run it on the board itself. The individual MSP430G2x are also pretty cheap. So if you blow one up you can always replace the chip.
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.
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.)