WM8281ECSSLASHR datasheet(77/392 Pages) CIRRUS

77 / 392 page

WM8281

Rev 4.0

The DRC also incorporates a Noise Gate function, which provides additional attenuation of very low-

level input signals. This means that the signal path is quiet when no signal is present, giving an

improvement in background noise level under these conditions.

A Signal Detect function is provided within the DRC; this can be used to detect the presence of an

audio signal, and used to trigger other events. The Signal Detect function can be used as an Interrupt

event, or as a GPIO output, or used to trigger the Control Write Sequencer (note - DRC1 only).

DRCnLMIX_VOL2

DRCnLMIX_VOL3

DRCnLMIX_VOL4

DRCnLMIX_VOL1

DRCnLMIX_SRC1

DRCnLMIX_SRC3

DRCnLMIX_SRC4

DRCnLMIX_SRC2

DRC1 Left (58h)

DRC2 Left (5Ah)

DRC

Dynamic Range Controller

DRCnRMIX_VOL2

DRCnRMIX_VOL3

DRCnRMIX_VOL4

DRCnRMIX_VOL1

DRCnRMIX_SRC1

DRCnRMIX_SRC3

DRCnRMIX_SRC4

DRCnRMIX_SRC2

DRC1 Right (59h)

DRC2 Right (5Bh)

DRC

Dynamic Range Controller

WM8281 supports 2 Stereo DRC blocks, ie. n = 1 or 2

Figure 30 Dynamic Range Control (DRC) Block

The DRC1 and DRC2 mixer control registers (see Figure 30) are located at register addresses R2240

(8C0h) through to R2271 (08DFh).

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.

The *_SRCn registers select the input source(s) for the respective DRC processing blocks. Note that

the selected input source(s) must be configured for the same sample rate as the DRC to which they

are connected. Sample rate conversion functions are available to support flexible interconnectivity -

see “Asynchronous Sample Rate Converter (ASRC)” and “Isochronous Sample Rate Converter

(ISRC)

”.

The bracketed numbers in Figure 30

, eg. “(58h)” indicate the corresponding *_SRCn register setting

for selection of that signal as an input to another digital core function.

The sample rate for the DRC function is configured using the FX_RATE register - see Table 23. Note

that the EQ, DRC and LHPF functions must all be configured for the same sample rate.

The DRC function supports audio sample rates in the range 8kHz to 96kHz. Higher sample rates (up

to 192kHz) may be selected using FX_RATE, provided that the DRC function is disabled.

Sample rate conversion is required when routing the DRC signal paths to any signal chain that is

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