UM10850
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User manual
Rev. 2.4 — 13 September 2016
233 of 464
NXP Semiconductors
UM10850
Chapter 16: LPC5410x Real-Time Clock (RTC)
16.6 Register description
Reset Values pertain to initial power-up of the device or when an RTC software reset is
applied (except where noted). This block is not initialized by any other system reset.
16.6.1 RTC CTRL register
This register controls which clock the RTC uses (1 kHz or 1 Hz) and enables the two RTC
interrupts to wake up the part from Deep power-down. To wake up the part from
Deep-sleep or Power-down modes, enable the RTC interrupts in the system control block
STARTLOGIC1 register.
Table 275. Register overview: RTC (base address 0x4003 C000)
Name
Access
Offset
Description
Reset
value
Reference
CTRL
R/W
0x000
RTC control register
0xF
MATCH
R/W
0x004
RTC match register
0xFFFF
COUNT
R/W
0x008
RTC counter register
0
WAKE
R/W
0x00C
RTC high-resolution/wake-up timer
control register
0
Table 276. RTC control register (CTRL, address 0x4003 C000) bit description
Bit
Symbol
Value Description
Reset
value
0
SWRESET
Software reset control
1
0
Not in reset. The RTC is not held in reset. This bit must be cleared prior to
configuring or initiating any operation of the RTC.
1
In reset. The RTC is held in reset.
All register bits within the RTC will be forced to their reset value except the OFD bit.
This bit must be cleared before writing to any register in the RTC - including writes
to set any of the other bits within this register.
Do not attempt to write to any bits of this register at the same time that the reset bit
is being cleared.
1
OFD
Oscillator fail detect status.
1
0
Run. The RTC oscillator is running properly. Writing a 0 has no effect.
1
Fail. RTC oscillator fail detected. Clear this flag after the following power-up.
Writing a 1 clears this bit.
2
ALARM1HZ
RTC 1 Hz timer alarm flag status.
1
0
No match. No match has occurred on the 1 Hz RTC timer. Writing a 0 has no effect.
1
Match. A match condition has occurred on the 1 Hz RTC timer. This flag generates
an RTC alarm interrupt request RTC_ALARM which can also wake up the part from
any low power mode. Writing a 1 clears this bit.
3
WAKE1KHZ
RTC 1 kHz timer wake-up flag status.
1
0
Run. The RTC 1 kHz timer is running. Writing a 0 has no effect.
1
Time-out. The 1 kHz high-resolution/wake-up timer has timed out. This flag
generates an RTC wake-up interrupt request RTC-WAKE which can also wake up
the part from any low power mode. Writing a 1 clears this bit.