WM8962B datasheet(83/295 Pages) WOLFSON

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WM8962

Rev 4.3

ADC RETUNE

DF1 Filter

ADC

ReTune

First Order

LPF/HPF

ADC Signal Enhancement path

DRC

3D Surround

Second Order

HPF

The ReTune function is part of both the ADC and the DAC Signal Enhancement paths. It can be

enabled on either path independently. Unique coefficient sets are supported for each path.

ReTuneTM is an advanced feature that is intended to perform frequency linearisation according to the

particular needs of the application microphone, loudspeaker or housing. The ReTune algorithms can

provide acoustic equalisation and selective phase (delay) control of specific frequency bands. In a

typical application, ReTune™ is used to flatten the response across the audio frequency band.

ReTune™ can also be configured to achieve other response patterns if required.

Note that, when using ReTune™ to boost any frequency band, it is recommended to take care not to

introduce distortion, taking into account the gain that may be applied by other audio enhancement

functions.

Before ReTuneTM is enabled, it must be initialised and configured using the DSP2_ENA bit described

in Table 37. Note that this bit only needs to be enabled once before using any or all of ADC ReTune,

DAC ReTune, DAC HPF, VSS or HD Bass.

Note that specific sequences must be followed when enabling or configuring ADC ReTune, DAC

ReTune, DAC HPF, VSS, and HD

Bass sound enhancement functions (see “Enable Sequence -

Enhancements Initially Disabled

”).

The ReTune function is enabled on the ADC path using the RTN_ADC_ENA register bit as described

in Table 37. Under default conditions, the Left and Right channels each use unique tuning coefficients.

When the ADC_RETUNE_SCV register is set, then both channels are controlled by the Right channel

coefficients.

For the derivation of ADC ReTune configuration parameters in registers R17920 to R19007, the Cirrus

WISCE™ software must be used to analyse the requirements of the application (refer to WISCETM for

further information.) If desired, one or more sets of register coefficients might be derived for different

operating scenarios, and these may be recalled and written to the CODEC registers as required in the

target application. The ADC ReTune configuration procedure involves the generation and analysis of

test signals as outlined below. Note that DSP2_ENA must be enabled before there is any type of

access of any of the parameters associated with ADC ReTune.

To determine the characteristics of the microphone in an application, a test signal is applied to a

loudspeaker that is in the acoustic path to the microphone. The received signal through the application

microphone is analysed and compared with the received signal from a reference microphone in order

to determine the characteristics of the application microphone.

Note that the ReTune configuration coefficients are specific to a particular speaker or microphone; it is

therefore required that the part-to-part variation in these components is small.

WM8962B Datasheet(PDF) 83 Page - Wolfson Microelectronics plc

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