ARMv7-M (Cortex-M3, M7) CPU registers

• General registers : R0 ~ R12
• Stack Pointer register : R13 (SP, banked to SP_main(MSP), SP_process(PSP))
• Link Register : R14 (LR)
• Program Counter : R15 (PC)
• (Program) Status registers (flags, execution state, exception number) : xPSR
• Mask registers (priority of exception and interrupt)
• Control register (CONTROL, current stack mode, current Thread mode privilege level)

    All other registers are memory-mapped.

* Reference : "ARMv7-M Architecture Reference Manual B1.4 Registers"