WM8994ECSSLASHR datasheet(153/363 Pages) CIRRUS

153 / 363 page

WM8994

Rev 4.6

153

SDOUT (4-WIRE SPI CONTROL INTERFACE DATA)

The WM8994 can support a number of different Control Interface protocols. In 4-wire SPI mode, a

GPIO pin must be configured as SDOUT. See “Control Interface” for further details.

A GPIO pin configured as SDOUT

can be configured as CMOS or Wired ‘OR’ using the SPI_CFG

configured as SDOUT.

INTERRUPT (IRQ) STATUS OUTPUT

The WM8994 has an Interrupt Controller which can be used to indicate when any selected Interrupt

events occur. An interrupt can be generated by any of the events described throughout the GPIO

function definition above. Individual interrupts may be masked in order to configure the Interrupt as

required. See “Interrupts” for further details.

The Interrupt (IRQ) status may be output directly on any GPIO pin by setting the respective GPIO

registers as de

scribed in “GPIO Control”.

OVER-TEMPERATURE DETECTION

The WM8994 incorporates a temperature sensor which detects when the device temperature is within

normal limits or if the device is approaching a hazardous temperature condition.

The Temperature status may be output directly on any GPIO pin by setting the respective GPIO

registers as described in “GPIO Control”. Any GPIO pin can be used to indicate either a Warning

Temperature event or the Shutdown Temperature event. De-bounce can be applied to the applicable

signal using the register bits described in Table 82.

The Warning Temperature and Shutdown Temperature status are inputs to the Interrupt control circuit,

after the selectable de-bounce. An interrupt event may be triggered on the rising and falling edges of

these signals. The associated interrupt bit is latched once set; it can be polled at any time or used to

control the IRQ signal. See “Interrupts” for more details of the Interrupt event handling.

Note that the temperature sensor can be configured to automatically disable the audio outputs of the

WM8994 (see “Thermal Shutdown”). In some applications, it may be preferable to manage the

temperature sensor event through GPIO or Interrupt functions, allowing a host processor to implement

a controlled system response to an over-temperature condition.

The temperature sensor must be enabled by setting the TSHUT_ENA register bit. When the

TSHUT_OPDIS is also set, then a device over-temperature condition will cause the speaker outputs

(SPKOUTL and SPKOUTR) of the WM8994 to be disabled.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R2 (0002h)

Power

Management

(2)

TSHUT_EN

Thermal sensor enable

0 = Disabled

1 = Enabled

TSHUT_OP

DIS

Thermal shutdown control

(Causes audio outputs to be disabled if an

overtemperature occurs. The thermal sensor

must also be enabled.)

0 = Disabled

1 = Enabled

R1864

(0748h)

IRQ

Debounce

TEMP_WAR

N_DB

Thermal Warning de-bounce

0 = Disabled

1 = Enabled

TEMP_SHU

T_DB

Thermal shutdown de-bounce

0 = Disabled

1 = Enabled

Table 82 Temperature Sensor Enable and GPIO/Interrupt Control

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