Texas Instruments TLV320AIC3109EVM-K, Руководство пользователя

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TLV320AIC3109EVM Software
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24 SLAU738 – September 2017
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TLV320AIC3109EVM-K
4.8.2.1 De-emphasis Filters
The de-emphasis filters used in the TLV320AIC3109-Q1 can be programmed as described in
TLV320AIC3109-Q1 Automotive, Low-Power, 96-kHz, Mono Audio Codec , using this tab. Enter the
coefficients for the de-emphasis filter response desired. While on this tab, the de-emphasis response is
shown on the
Effect Filter Response graph; however, note that this response is not included in graphs of
other effect responses when on the other filter design tabs.
Figure 18. De-emphasis Filters
4.8.2.2 DAC Digital Effects Filter
The digital audio input stream can be routed through the digital effects filter in the codec before routing to
the DAC to allow custom audio performance. The digital effects filter cannot operate on both the ADC or
DAC at the same time. The digital effects filter operation is discussed in
Section 4.8.3 .
4.8.3 Digital Effects Filters
The digital effect filters (or biquad filters) of the TLV320AIC3109-Q1 are selected using the check boxes
shown in the
Figure 17 tab. The De-emphasis filters are described in TLV320AIC3109-Q1 Automotive,
Low-Power, 96-kHz, Mono Audio Codec , and their coefficients may be changed.
When designing filters for use with TLV320AIC3109-Q1, the software allows for several different filter
types to be used. These options are shown on a tab control in the lower left corner of the screen. When a
filter type is selected, and suitable input parameters defined, the response is shown in the
Effect Filter
Response graph. Regardless of the setting for enabling the Effect Filter, the filter coefficients are not
loaded into the TLV320AIC3109-Q1 until the Download Coefficients button is pressed. To avoid noise
during the update of coefficients, it is recommended for the user to uncheck the Effect Filter check box
before downloading coefficients. Once the desired coefficients are in the TLV320AIC3109-Q1, enable the
filters by checking the
Effect Filters box again.
4.8.3.1 Shelf Filters
A shelf filter is a simple filter that applies a gain (positive or negative) to frequencies above or below a
certain corner frequency. As shown in
Figure 19 , in Bass mode a shelf filter applies a gain to frequencies
below the corner frequency; in Treble mode the gain is applied to frequencies above the corner frequency.