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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
698 of 808
NXP Semiconductors
UM10360
Chapter 34: Appendix: Cortex-M3 User Guide
[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.
3.1.3.1
General-purpose registers
R0-R12 are 32-bit general-purpose registers for data operations.
3.1.3.2
Stack Pointer
The
Stack Pointer
(SP) is register R13. In Thread mode, bit[1] of the CONTROL register
indicates the stack pointer to use:
On reset, the processor loads the MSP with the value from address
0x00000000
.
•
0 =
Main Stack Pointer
(MSP). This is the reset value.
•
1 =
Process Stack Pointer
(PSP).
3.1.3.3
Link Register
The
Link Register
(LR) is register R14. It stores the return information for subroutines,
function calls, and exceptions. On reset, the processor loads the LR value
0xFFFFFFFF.
3.1.3.4
Program Counter
The
Program Counter
(PC) is register R15. It contains the current program address.
Bit[0] is always 0 because instruction fetches must be halfword aligned. On reset, the
processor loads the PC with the value of the reset vector, which is at address
0x00000004
.
3.1.3.5
Program Status Register
The
Program Status Register
(PSR) combines:
•
Application Program Status Register
(APSR)
•
Interrupt Program Status Register
(IPSR)
•
Execution Program Status Register
(EPSR).
These registers are mutually exclusive bitfields in the 32-bit PSR. The bit assignments
are:
EPSR
RO
Privileged
0x01000000
PRIMASK
RW
Privileged
0x00000000
FAULTMASK
RW
Privileged
0x00000000
BASEPRI
RW
Privileged
0x00000000
CONTROL
RW
Privileged
0x00000000
Table 598.
Core register set summary
Name
Type
[1]
Required
privilege
[2]
Reset
value
Description