Cirrus Logic CS42L51 - Manual (Page 35)

DS679F1 35
CS42L51
4.4.2 Volume Controls
Three digital volume control functions are implemented, offering independent control over the ADC and
PCM signal paths into the mixer as well as a combined control over the mixed signals. All volume controls
are programmable to ramp in increments of 0.125 dB at a rate controlled by the DAC soft ramp/zero cross
settings.
All signal paths may also be independently muted via mute control bits. When enabled, each bit attenu-
ates the signal to its maximum value. When the mute bit is disabled, the signal returns to the attenuation
level set in the respective volume control register. The attenuation is ramped up and down at the rate
specified by the DAC_SZC[1:0] bits.
4.4.3 Mono Channel Mixer
A channel mixer may be used to create a mix of the left and right channels for either the PCM or ADC
signals. This mix allows the user to produce a MONO signal from a stereo source. The mixer may also be
used to implement a left/right channel swap.
4.4.4 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 limiter
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, AOUTx_VOL[7:0], will affect the Beep vol-
ume, DAC volume may alternatively be controlled using the PCMMIXx_VOL[6:0] bits.
Software
Controls:
“ADCx Mixer Volume Control: ADCA (Address 0Eh) & ADCB (Address 0Fh)” on page 61 , “PCMX
Mixer Volume Control: PCMA (Address 10h) & PCMB (Address 11h)” on page 62 , “AOUTx Vol-
ume Control: AOUTA (Address 16h) & AOUTB (Address 17h)” on page 66 , “DAC Output Control
(Address 08h)” on page 57 .
Software
Controls:
“PCM Channel Mixer (Address 18h)” on page 67 .
Software
Controls: “Beep Frequency & Timing Configuration (Address 12h)” on page 62 , “Beep Off Time & Volume
(Address 13h)” on page 63 , “Beep Configuration & Tone Configuration (Address 14h)” on page 64
Gain
dB
-10dB
0dB
Frequency
T2 = 15 µs
T1=50 µs
F1 F2
3.183 kHz 10.61 kHz
Figure 14. De-Emphasis Curve