WM8321 datasheet(47/253 Pages) WOLFSON

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Production Data

WM8321

PD, February 2012, Rev 4.0

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R16529 (4091h)

Clock Control 2

XTAL_INH

Crystal Start-Up Inhibit

0 = Disabled

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

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.

XTAL_BKUPE

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

BIT

LABEL

DESCRIPTION

R16404

(4014h)

Interrupt Status

XTAL_START_EINT

Crystal Oscillator Start Failure interrupt

(Rising Edge triggered)

Note: Cleared when a ‘1’ is written.

XTAL_TAMPER_EINT

Crystal Oscillator Tamper interrupt

(Rising and Falling Edge triggered)

Note: Cleared when a ‘1’ is written.

R16412

(401Ch)

Interrupt Status

4 Mask

IM_XTAL_START_EINT

Interrupt mask.

0 = Do not mask interrupt.

1 = Mask interrupt.

Default value is 1 (masked)

Table 17 Crystal Oscillator (XTAL) Interrupts

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