[iheartmemcache]

Not really challenging at all. ST subsidized the release of Keil IDE with a pretty decent amount of functionality. Use uVision Core[1] and you get a Crazy amount of control over everything (CMSIS is worth paying for, and if you're an academic, discounts are offered.). No licensing fees at all. Works with the standard ULINKs. What used to cost tends of thousands of dollars for a bond-out chip in the 80s.

The Cortex M3 (and any of the other ARMs that offer ETM[2]) is as good if not better than any debugger I've ever used[3], software, hardware, micros, CPLD's, FPGAs. You need to throw a few hundred down for the ULINKpro, but the Segger ST everyone uses I think speaks ETM. Making the jump from Arduino to UL certified production run consumer products with injection molded custom casing holding your 6 layer board has never been easier.

ST even offers documentation on how to use FreeRTOS[4] if you need hard scheduling requirements (though I'd go with Micrim, Wind River, or one of the usual suspects that has already been vetted if you're going to market in, say, the medical device industry).

[1] http://www2.keil.com/coresight/ [2] http://www.ecnmag.com/article/2010/07/debug-code-arm-cortex-... [3] Cincom Smalltalk notwithstanding. [4] http://www.st.com/web/en/catalog/tools/PF260200