CS48L32 datasheet(63/192 Pages) CIRRUS

63 / 192 page

DS1219F4

Cirrus Logic

CS48L32

4.3 Digital Core

4.3.9

Noise Generator

The CS48L32 incorporates a white-noise generator that can be routed within the digital core. The main purpose of the

noise generator is to provide comfort noise in cases where silence (digital mute) is not desirable.

Figure 4-24. Digital-Core Noise Generator

The noise generator can be selected as input to any of the digital mixers or signal-processing functions within the CS48L32

digital core. The hexadecimal number (0x00C) in Fig. 4-24 indicates the corresponding x_SRCn setting for selection of the

noise generator as an input to another digital-core function.

The sample rate for the noise generator is configured using NOISE_GEN_RATE. See Table 4-21. Note that sample-rate

conversion is required when routing the noise generator output to any signal chain that is configured for a different sample

rate.

The noise generator is enabled by setting NOISE_GEN_EN, described in Table 4-19. The signal level is configured using

NOISE_GEN_GAIN.

4.3.10 PWM Generator

The CS48L32 incorporates two PWM signal generators as shown in Fig. 4-25. The duty cycle of each PWM signal can be

modulated by an audio source, or can be set to a fixed value using a control register setting.

A four-input mixer is associated with each PWM generator. The four input sources are selectable in each case, and

independent volume control is provided for each path.

PWM signal generators can be output directly on a GPIO pin. See Section 4.10 to configure a GPIO pin for this function.

Note that the PWM signal generators cannot be selected as input to the digital mixers or signal-processing functions within

the CS48L32 digital core.

Table 4-19. Noise Generator Control

Bit

Label

Default

Description

R46080 (0xB400)

Comfort_Noise_

Generator

NOISE_GEN_EN

Noise Generator Enable

0 = Disabled

1 = Enabled

4:0

NOISE_GEN_

GAIN[4:0]

0x00

Noise generator signal level

0x00 = –114 dBFS

0x01 = –108 dBFS

0x02 = –102 dBFS

…(6 dB steps)

0x12 = –6 dBFS

0x13 = 0 dBFS

All other codes are

reserved

Noise Generator (0x00C)

White Noise

Generator

NOISE_GEN_EN p. 63

NOISE_GEN_GAIN[4:0] p. 63

NOISE_GEN_RATE[4:0] p. 68

CS48L32 Datasheet(PDF) 63 Page - Cirrus Logic

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