WM1811A datasheet(143/328 Pages) WOLFSON

143 / 328 page

Production Data

WM1811A

PD, November 2013, Rev 4.1

143

BUTTON DETECT (GPIO INPUT)

Button detect functionality can be selected on any GPIO pin by setting the respective GPIO registers

as described in “GPIO Control”. The same functionality can be used to support a Jack Detect input

function.

It is recommended to enable the GPIO input de-bounce feature when using GPIOs as button input or

Jack Detect input.

The GPn_LVL fields may be read to determine the logic levels on a GPIO input, after the selectable

de-bounce controls.Note that GPn_LVL is not affected by the GPn_POL bit.

The de-bounced GPIO signals are also inputs to the Interrupt control circuit. An interrupt event is

triggered on the rising and falling edge of the GPIO input. The associated interrupt bits are 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.

LOGIC ‘1’ AND LOGIC ‘0’ OUTPUT (GPIO OUTPUT)

The WM1811A can be programmed to drive a logic high or logic low level on any GPIO pin by

selecting the “GPIO Output” function as described in “GPIO Control”. The output logic level is selected

using the respective GPn_LVL bit.

Note that the polarity of the GPIO output can be inverted using the GPn_POL registers. If GPn_POL =

1, then the external output will be the opposite logic level to GPn_LVL.

INTERRUPT (IRQ) STATUS OUTPUT

The WM1811A 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 described in “GPIO Control”.

OVER-TEMPERATURE DETECTION

The WM1811A 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 81.

The Warning Temperature and Shutdown Temperature status are inputs tothe 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

WM1811A (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 WM1811A to be disabled.

WM1811A Datasheet(PDF) 143 Page - Wolfson Microelectronics plc

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