Cortex®-M3 processors have registers R0 to R15.
R0 to R12 are general-purpose registers.
R13 is a register with a bank configuration that switches between two types of stack pointers.
R14 is the link register and R15 is the program counter.
Special registers that control the special features of the Cortex®-M3 processor are also available.
* Arm and Cortex are registered trademarks of Arm Limited (or its subsidiaries) in the US and/or elsewhere.