Production Data
WM8321
ADDRESS
R16529 (4091h)
Clock Control 2
BIT
LABEL
DEFAULT
DESCRIPTION
XTAL_INH
Crystal Start-Up Inhibit
0 = Disabled
15
0
1 = Enabled
When XTAL_INH=0, the internal
RC oscillator will provide CLKOUT
until the crystal oscillator is valid.
When XTAL_INH=1, the ‘ON’
transition is inhibited until the
crystal oscillator is valid.
XTAL_ENA
Crystal Oscillator Enable
0 = Disabled at all times
13
0
1 = Enabled in OFF, ON, SLEEP
states
(Note that the BACKUP behaviour
is determined by
XTAL_BKUPENA.)
This field can only be written to by
loading configuration settings from
OTP/ICE. In all other cases, this
field is Read Only.
12
XTAL_BKUPE
NA
1
Selects the RTC and 32.768kHz
oscillator in BACKUP state
0 = RTC unclocked in BACKUP
1 = RTC maintained in BACKUP
(Note that XTAL_ENA must also
be set if the RTC is to be
maintained in BACKUP)
Table 16 Clocking Control
13.2 CRYSTAL OSCILLATOR INTERRUPTS
The Crystal Oscillator (XTAL) is associated with two Interrupt event flags.
The XTAL_START_EINT interrupt is set if the crystal oscillator fails to start-up within a timeout period
of approximately 24 seconds.
The XTAL_TAMPER_EINT interrupt is set if the crystal oscillator is stopped unexpectedly (eg. due to
tampering). Note that this interrupt is only supported if the crystal oscillator has previously started up
successfully. The XTAL_TAMPER_EINT is also set if the crystal oscillator is re-started following an
unexpected interruption.
Each of these secondary interrupts triggers a primary Real Time Clock and Crystal Oscillator
Interrupt, RTC_INT (see Section 23). In the case of XTAL_START_EINT, this can be masked by
setting the mask bit(s) as described in Table 17.
ADDRESS
R16404
(4014h)
BIT
LABEL
DESCRIPTION
Crystal Oscillator Start Failure interrupt
(Rising Edge triggered)
XTAL_START_EINT
7
Interrupt Status
4
Note: Cleared when a ‘1’ is written.
Crystal Oscillator Tamper interrupt
(Rising and Falling Edge triggered)
Note: Cleared when a ‘1’ is written.
Interrupt mask.
XTAL_TAMPER_EINT
IM_XTAL_START_EINT
6
7
R16412
(401Ch)
0 = Do not mask interrupt.
Interrupt Status
4 Mask
1 = Mask interrupt.
Default value is 1 (masked)
Table 17 Crystal Oscillator (XTAL) Interrupts
PD, February 2012, Rev 4.0
47
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
