WM8281ECSSLASHR datasheet(62/392 Pages) CIRRUS

62 / 392 page

WM8281

Rev 4.0

DIGITAL CORE

The WM8281 digital core provides extensive mixing and processing capabilities for multiple signal

paths. The configuration is highly flexible, and virtually every conceivable input/output connection can

be supported between the available processing blocks.

The digital core provides parametric equalisation (EQ) functions, dynamic range control (DRC), low-

pass / high-pass filters (LHPF), and programmable DSP capability. The DSP can support functions

such as wind noise, side-tone or other programmable filters, also dynamic range control and

compression, or virtual surround sound and other audio enhancements.

The WM8281 supports multiple signal paths through the digital core. Stereo full-duplex sample rate

conversion is provided to allow digital audio to be routed between input (ADC) paths, output (DAC)

paths, Digital Audio Interfaces (AIF1, AIF2 and AIF3) and SLIMbus paths operating at different

sample rates and/or referenced to asynchronous clock domains.

The DSP functions are highly programmable, using application-specific control sequences. It should

be noted that the DSP configuration data is lost whenever the DCVDD power domain is removed; the

DSP configuration data must be downloaded to the WM8281 each time the device is powered up.

The procedure for configuring the WM8281

DSP functions is tailored to each customer’s application;

please contact your local Cirrus Logic representative for more details.

The WM8281 incorporates two 1kHz tone generators which ca

n be used for ‘beep’ functions through

any of the audio signal paths.

A white noise generator is incorporated, to provide ‘comfort noise’ in

cases where silence (digital mute) is not desirable.

A haptic signal generator is provided, for use with external haptic devices (eg. mechanical vibration

actuators). Two Pulse Width Modulation (PWM) signal generators are also provided; the PWM

waveforms can be modulated by an audio source within the digital core, and can be output on a GPIO

pin.

The WM8281 also incorporates the Cirrus Logic Ambient Noise Cancellation (ANC) functionality; note

that this is described in a separate section, see “Ambient Noise Cancellation”.

An overview of the digital core processing and mixing functions is provided in Figure 22. An overview

of the external digital interface paths is provided in Figure 23.

The control registers associated with the digital core signal paths are shown in Figure 24 through to

Figure 41.

The full list of digital mixer control registers is provided in the “Register Map” section

(Register R1600 through to R3000). Generic register definitions are provided in Table 8.

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