Datasheet
UM10398 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
User manual Rev. 12.3 — 10 June 2014 514 of 547
NXP Semiconductors
UM10398
Chapter 28: LPC111x/LPC11Cxx Appendix: ARM Cortex-M0 reference
28.6.3.5 System Control Register
The SCR controls features of entry to and exit from low power state. See the register
summary in Table 28–449
for its attributes. The bit assignments are:
Table 452. AIRCR bit assignments
Bits Name Type Function
[31:16] Read: Reserved
Write: VECTKEY
RW Register key:
Reads as Unknown
On writes, write
0x05FA
to VECTKEY, otherwise the
write is ignored.
[15] ENDIANESS RO Data endianness implemented:
0 = Little-endian
1 = Big-endian.
[14:3] - - Reserved
[2] SYSRESETREQ WO System reset request:
0 = no effect
1 = requests a system level reset.
This bit reads as 0.
[1] VECTCLRACTIVE WO Reserved for debug use. This bit reads as 0. When
writing to the register you must write 0 to this bit,
otherwise behavior is Unpredictable.
[0] - - Reserved.
Table 453. SCR bit assignments
Bits Name Function
[31:5] - Reserved.
[4] SEVONPEND Send Event on Pending bit:
0 = only enabled interrupts or events can wake-up the processor,
disabled interrupts are excluded
1 = enabled events and all interrupts, including disabled interrupts,
can wake-up the processor.
When an event or interrupt enters pending state, the event signal
wakes up the processor from WFE. If the processor is not waiting for
an event, the event is registered and affects the next WFE.
The processor also wakes up on execution of an
SEV
instruction.
[3] - Reserved.
[2] SLEEPDEEP Controls whether the processor uses sleep or deep sleep as its low
power mode:
0 = sleep
1 = deep sleep.
[1] SLEEPONEXIT Indicates sleep-on-exit when returning from Handler mode to Thread
mode:
0 = do not sleep when returning to Thread mode.
1 = enter sleep, or deep sleep, on return from an ISR to Thread
mode.
Setting this bit to 1 enables an interrupt driven application to avoid
returning to an empty main application.
[0] - Reserved.