WM8321
Production Data
The WM8321 provides two interrupt flags associated with the crystal oscillator, as described in
Section 13.2. These interrupts will provide indication of a crystal oscillator start-up failure, or detection
of an interruption to the crystal oscillator (eg, due to tampering).
The CLKOUT control fields are described in Table 16. Some of these controls may also be stored in
the integrated OTP memory. See Section 14 for details.
The 32.768kHz oscillator may also be output on a GPIO pin, as described in Section 21. Note that a
GPIO pin configured as 32.768kHz output will continue to output the oscillator clock in the OFF power
state; this may be used to provide clocking to the processor in the OFF state, provided that the
selected power domain for that GPIO pin remains enabled in the OFF state. The CLKOUT output is
always disabled in the OFF power state.
The internal RC oscillator generates the required clocks for the integrated DC-DC Converters on the
WM8321. Note that a 2MHz ‘External Power Clock’, derived from this oscillator, may be output on a
GPIO pin to provide synchronised clocking of external DC-DC Converters if required (see Section 21).
The 2MHz External Power Clock is only enabled when either of the External Power Enable signals
EPE1 or EPE2 is asserted. The External Power Enable (EPE) signals are controlled as described in
Section 15.3.
Note that the CLKOUT_ENA control register is locked by the WM8321 User Key. This register can
only be changed by writing the appropriate code to the Security register, as described in Section 12.4.
ADDRESS
R16397 (400Dh)
System Status
BIT
LABEL
DEFAULT
DESCRIPTION
Crystal Oscillator Status
0 = Disabled or in start-up phase
1 = Enabled and verified
CLKOUT output enable
0 = Disabled
XTAL_OK
7
0
R16528 (4090h)
Clock Control 1
CLKOUT_ENA
15
0
1 = Enabled
Protected by user key
CLKOUT pin configuration
0 = CMOS
CLKOUT_OD
CLKOUT_SLOT
13
0
1 = Open Drain
CLKOUT output enable ON slot
select
10:8
000
000 = Do not enable
001 = Enable in Timeslot 1
010 = Enable in Timeslot 2
011 = Enable in Timeslot 3
100 = Enable in Timeslot 4
101 = Enable in Timeslot 5
110 = Do not enable
111 = Do not enable
CLKOUT_SLP
SLOT
CLKOUT output SLEEP slot select
000 = Controlled by CLKOUT_ENA
001 = Disable in Timeslot 5
010 = Disable in Timeslot 4
011 = Disable in Timeslot 3
100 = Disable in Timeslot 2
101 = Disable in Timeslot 1
110 = Controlled by CLKOUT_ENA
111 = Controlled by CLKOUT_ENA
6:4
000
PD, February 2012, Rev 4.0
46
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
