ZL50233 Data Sheet
21
Zarlink Semiconductor Inc.
Note: In order to correctly write to Control Register 1 and 2 of ECB, it is necessary to write the data twice to the register, one
immediately after another. The two writes must b e separated by at least 350 ns and no mor e than 20 us.
Echo Canceller B (ECB): Control Register 1
Power-up 02hex R/W Address: 20hex + Base Address
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset INJDis BBM PAD Bypass AdpDis 1 0
Functional Description of Register Bits
Reset When high, the power-up initialization is executed which presets all register bits including this bit
and clears the Adaptive Filter coefficients.
INJDis When high, the noise injection process is disabled. When low, noise injection is enabled.
BBM When high, the Back to Back configuration is enabled. When low, the Normal configuration is
enabled. Note: Do not enable Extended-Delay and BBM configuration s at the s ame time. Always
set both BBM bits of the two echo cancellers (Control Reg ister 1) of the sa me group to the s ame
logic value to avoid conflict.
PAD When high, 12 dB of attenuation is inserted into the Rin to Rout path. When low, the Gains
register controls the signal levels.
Bypass When high, Sin data is by-passed to Sout and Rin data is by-passed to Rout. The Adaptive Filter
coeffic ie nts are set to zero and the filter adaptation is stopped. When low, output data on both
Sout and Rout is a function of the echo canceller algorithm.
AdpDis When high, echo canceller adaptation is disabled. The Voice Processor cancels echo.
When low, the ech o canceller dynamically adapts to the echo path characteristics.
1 Bits marked as “1” or “0” are reserved bits and should be written as indicated.
0 Control Register 1 (Echo Canceller B) Bit 0 is a reserved bit and should be written “0”.
Power-up
00hex
ECA: Control Register 2 R/W Address:
01hex + Base Address
ECB: Control Register 2 R/W Address:
21hex + Base Address
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
TDis PHDis NLPDis AutoTD NBDis HPFDis MuteS MuteR
Functional Description of Register Bits
TDis When high, tone detection is disabled. When low, tone detection is enabled. When both Echo
Cancellers A and B TDis bits are high, Tone Disable processors are disabled entirely and are put
into Power Down mode.
PHDis When high, the tone detectors will trigger upon the presence of a 2100 Hz tone regardless of the
presence/absence of periodic phase reversals. When low, the tone detectors will trigger only upon
the presence of a 2100 Hz tone with periodic phase reversals.
NLPDis When high, the non-linear processor is disabled. When low, the non-linear processors function
normally. Useful for G.165 conformance testing.
AutoTD When high, the echo canceller puts itself in Bypass mode when the tone detectors detect the
presence of 2100 Hz tone. See PHDis for qualification of 2100 Hz tones.
When low, the echo canceller algorithm will remain operational regardless of the state of the
2100 Hz tone detectors.
NBDis When high, the narrow-band detector is disabled. When low, the narrow-band detector is enabled.
HPFDis When high, the offset nulling high pass filters are bypassed in the Rin and Sin paths. When low,
the offset nulling filters are active and will remove DC offsets on PCM input signals.
MuteS When high, data on Sout is muted to quiet code. When low, Sout carries active code.
MuteR When high, data on Rout is muted to quiet code. When low, Rout carries active code.