CS43L22 datasheet(23/68 Pages) CIRRUS

23 / 68 page

DS792F1

CS43L22

Confidential Draft

10/7/08

4.2.1

Beep Generator

The Beep Generator generates audio frequencies across approximately two octave major scales. It offers

three modes of operation: Continuous, multiple and single (one-shot) beeps. Sixteen on and eight off

times are available.

Note:

The Beep is generated before the limiter and may affect desired limiting performance. If the lim-

iter function is used, it may be required to set the beep volume sufficiently below the threshold to prevent

the peak detect from triggering. Since the master volume control, MSTxVOL[7:0], will affect the beep vol-

ume, DAC volume may alternatively be controlled using the PCMxVOL[6:0] bits.

4.2.2

Limiter

When enabled, the limiter monitors the digital input signal before the DAC and PWM modulators, detects

when levels exceed the maximum threshold settings and lowers the master volume at a programmable

attack rate below the maximum threshold. When the input signal level falls below the maximum threshold,

the AOUT volume returns to its original level set in the Master Volume Control register at a programmable

release rate. Attack and release rates are affected by the DAC soft ramp/zero cross settings and sample

rate, Fs. Limiter soft ramp and zero cross dependency may be independently enabled/disabled.

Notes:

Recommended settings: Best limiting performance may be realized with the fastest attack and

slowest release setting with soft ramp enabled in the control registers. The MIN bits allow the user to

set a threshold slightly below the maximum threshold for hysteresis control - this cushions the sound

as the limiter attacks and releases.

The Limiter maintains the output signal between the CUSH and MAX thresholds. As the digital input

signal level changes, the level-controlled output may not always be the same but will always fall within

Referenced Control

MSTxVOL[7:0].....................

PCMxVOL[6:0] ....................

OFFTIME[2:0] .....................

ONTIME[3:0] .......................

FREQ[3:0] ...........................

BEEP[1:0]............................

BEEPMIXDIS ......................

BPVOL[4:0] .........................

“Master Volume Control: MSTA (Address 20h) & MSTB (Address 21h)” on page 52

“PCMx Volume: PCMA (Address 1Ah) & PCMB (Address 1Bh)” on page 48

“Beep Off Time” on page 49

“Beep On Time” on page 49

“Beep Frequency” on page 48

“Beep Configuration” on page 50

“Beep Mix Disable” on page 50

“Beep Volume” on page 50

FREQ[3:0]

...

BPVOL[4:0]

ONTIME[3:0]

OFFTIME[2:0]

BEEP[1:0] =

'01'

BEEP[1:0] =

'10'

BEEP[1:0] =

'11'

SINGLE-BEEP: Beep turns on at a

configurable frequency (FREQ) and

volume (BPVOL) for the duration of

ONTIME. BEEP must be cleared

and set for additional beeps.

MULTI-BEEP: Beep turns on at a configurable frequency (FREQ)

and volume (BPVOL) for the duration of ONTIME and turns off for

the duration of OFFTIME. On and off cycles are repeated until

BEEP is cleared.

CONTINUOUS BEEP: Beep turns on at a configurable frequency (FREQ) and volume (BPVOL) and remains on

until BEEP is cleared.

Figure 6. Beep Configuration Options

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