With the cortex-m0 parts now hitting the market I think it is time to bring up the topic of thumb support again, not arm not thumb2 but thumb (the only common instruction set across almost the entire arm family (the exception being the pre-armv4t)).

cortex-m0 and -m1 are armv6-m based, the -m3 and -m4 are armv7m based.

I count something like 20 armv6m instructions that are not in the all thumb variants category. something like 148 armv7m that are not supported by armv6m nor all thumb variants. Just a rough count.

This is why you will see folks saying that the cortex-m0 and -m1 are thumb only not thumb2.

The cortex-m0 based mbed's have hit the street btw, available at sparkfun and other places. Note that gcc and llvm fail to build working code for the cortex-m0, when you specify cortex-m0 you get thumb2 code which fails miserably.

David



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