Цитата(Dron_Gus @ Dec 20 2011, 19:46)

Видимо, доступ к соответствующим регистрам разрешен только в привилегированном режиме.
Угу. Информация из первых рук:

The privilege levels for software execution are:
• Unprivileged
The software:
– has limited access to the MSR and MRS instructions, and cannot use the CPS instruction
– cannot access the system timer, NVIC, or system control block
– might have restricted access to memory or peripherals.
Unprivileged software executes at the unprivileged level.
• Privileged
The software can use all the instructions and has access to all resources.
Privileged software executes at the privileged level.