CS47L85 datasheet(99/370 Pages) CIRRUS

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CS47L85

Rev 4.3

TONE GENERATOR

The CS47L85

incorporates two 1kHz tone generators which can be used for ‘beep’ functions through any of the audio signal

paths. The phase relationship between the two generators is configurable, providing flexibility in creating differential signals,

or for test scenarios.

Tone Generator 1 (04h)

Tone Generator 2 (05h)

1kHz

Tone Generator

TONE1_ENA

TONE2_ENA

TONE_OFFSET

TONE_RATE

TONE1_OVD

TONE1_LVL

TONE2_OVD

TONE2_LVL

Figure 33 Digital Core Tone Generator

The tone generators can be selected as input to any of the digital mixers or signal processing functions within the CS47L85

digital core. The bracketed numbers in Figure 33,

e.g.,”(04h)” indicate the corresponding *_SRCn register setting for

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

SYSCLK must be present and enabled before setting the TONEn_ENA bits. The tone generators should be kept disabled

(TONEn

_ENA=0) if SYSCLK is not enabled. See “Clocking and Sample Rates” for further details (including requirements

for reconfiguring SYSCLK while digital core functions are enabled).

The sample rate for the tone generators is configured using the TONE_RATE register - see Table 22. Note that sample rate

conversion is required when routing the tone generator output(s) to any signal chain that is asynchronous and/or configured

for a different sample rate.

The tone generators are enabled using the TONE1_ENA and TONE2_ENA register bits as described in Table 18. The phase

relationship is configured using TONE_OFFSET.

The tone generators can also provide a configurable DC signal level, for use as a test signal. The DC output is selected

using the TONEn_OVD register bits, and the DC signal amplitude is configured using the TONEn_LVL registers, as

described in Table 18.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R32

(0020h)

Tone_Gen

erator_1

9:8

TONE_OFFSET

[1:0]

Tone Generator Phase Offset

Sets the phase of Tone Generator 2

relative to Tone Generator 1

00 = 0 degrees (in phase)

01 = 90 degrees ahead

10 = 180 degrees ahead

11 = 270 degrees ahead

TONE2_OVD

Tone Generator 2 Override

0 = Disabled (1kHz tone output)

1 = Enabled (DC signal output)

The DC signal level, when selected, is

configured using TONE2_LVL[23:0]

TONE1_OVD

Tone Generator 1 Override

0 = Disabled (1kHz tone output)

1 = Enabled (DC signal output)

The DC signal level, when selected, is

configured using TONE1_LVL[23:0]

TONE2_ENA

Tone Generator 2 Enable

0 = Disabled

1 = Enabled

TONE1_ENA

Tone Generator 1 Enable

0 = Disabled

1 = Enabled

CS47L85 Datasheet(PDF) 99 Page - Cirrus Logic

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