Cirrus Logic AN168 - Manual (Page 12)

AN168
12 AN168REV2
Configure the CS6422 from reset with the
following:
1) Mic set to '1' or '0', depending on whether the
internal mic preamp is used or not
2) GB = 0.75 dB/ms
3) RVol = +18 dB (this is the default setting; RVol
should be set between +6 dB and +30 dB)
4) Taps = 55.5 ms
5) TVol = 0 dB (this is the default setting; close to
0 dB is better; TVol should be between 0 dB
and +12 dB)
6) NseRmp = 12 dB/s
7) HDly = 150 ms
8) IdlTx = enabled
9) TSAtt = 24 dB
10) PCSen = low
11) TSThd = 12 dB
12) TSBias = 18 dB (default setting)
13) AErle = 18 dB
14) AFNse = -42 dB
15) TGain = 0 dB (can be 0 dB, +6 dB, +9.5 dB, or
+12 dB, depending on mic preamp require-
ments)
16) NECD = ‘1’ (should be '0' if a network sidetone
is present)
17) ASdt = -18 dB
The register configuration which implements the
above is:
reg 0: 1400 (9400 if internal mic preamp is
used)
reg 1: 0a22
reg 2: 0a14
reg 3: a046
reg 4: 5008
reg 5: 018a
1.4.2 Tweaking the Parameters
1) TGain can be set to 0 dB, +6 dB, +9.5 dB, or
+12 dB, to add gain to the mic preamp if need-
ed based on acoustic coupling tests.
2) RVol can be adjusted down or up based on de-
sired signal level. The value should be kept be-
tween +6 dB and +30 dB.
3) TVol can be adjusted to a value between 0 dB
and +12 dB to add gain to the transmit path,
particularly if the mic preamp gain was reduced
to satisfy acoustic coupling requirements.
4) TSThd controls the ERLE level at which the
transmit suppressor engages during far-end sin-
gle-talk (when the far-end is talking while the
near-end listener is silent). This parameter is
tested using the Far-End Single-Talk Counting
Test described in the Tests section.
5) TSBias controls the ERLE level at which the
transmit suppressor disengages during dou-
ble-talk. Lower values make it easier to disen-
gage the transmit suppressor, preventing the
undesirable attenuation of near-end speech.
This parameter is tested using the Double-talk
test described in the Tests section.
6) AErle and AFNse control the behavior of the
transition between half-duplex and full-duplex.
Specifically, they influence the time it takes for
the CS6422 to transition between half-duplex
and full-duplex. Lower values of AErle tend to
decrease the transition time. This parameter is
tested using the Full-duplex Transition test de-
scribed in the Tests section.
7) TSAtt controls the amount of attenuation added
to the transmit path when the transmit suppres-
sor engages. This parameter is tested using the
Far-End Single Talk Test described in the Tests
section.
8) IdlTx causes the half-duplex engine to switch to
transmit during an idle period. This parameter
only has an effect during half-duplex operation.