2.5.1.3.2 Stack Pointer
The Stack Pointer (SP) is register R13. In Thread mode, bit[1] of the CONTROL register indicates the stack pointer to use:
- 0: Main Stack Pointer (MSP). This is the reset value
- 1: Process Stack Pointer (PSP)
On reset, the processor loads the MSP with the value from address 0x00000000.