2.5.1.3 Core Registers

The following figure shows the processor core registers.

Figure 2-2. Core Register Set
Table 2-2. Core Register Set Summary
Name Type1 Required Privilege2 Reset Value Description
R0-R12 RW Either Unknown General-Purpose Registers
MSP RW Privileged See description Stack Pointer
PSP RW Either Unknown Stack Pointer
LR RW Either 0xFFFFFFFF Link Register
PC RW Either See description Program Counter
PSR RW Privileged Unknown Program Status Register
ASPR RW Either Unknown Application Program Status Register
IPSR RO Privileged 0x00000000 Interrupt Program Status Register
EPSR RO Privileged 0x01000000 Execution Program Status Register
PRIMASK RW Privileged 0x00000000 Priority Mask Register
FAULTMASK RW Privileged 0x00000000 Fault Mask Register
BASEPRI RW Privileged 0x00000000 Base Priority Mask Register
CONTROL RW Privileged 0x00000000 CONTROL Register
Note:
  1. Describes access type during program execution in Thread mode and Handler mode. Debug access can differ.
  2. An entry of Either means privileged and unprivileged software can access the register.

The following sections describe these registers in detail.