This specification describes the Bt8110 and Bt8110B multichannel ADPCM processor
CMOS integrated circuits that implement Adaptive Differential Pulse-Code Modulation
(ADPCM) encoding and decoding. The fixed-rate coding algorithms include those
specified in ANSI Standard T1.303-1989. These algorithms are identical to those in
ITU-T Recommendations G.726 and G.727. These circuits also implement the
variable-rate or embedded codes specified in ANSI Standard T1.310-1991 and ITU-T
Recommendation G.727.
A single ADPCM processor integrated circuit can provide 24 or 32 full-duplex
channels of ADPCM processing (encoding and decoding). In some applications, two
circuits can be combined to provide 48 or 64 full-duplex channels. Both A-law and µ-law
PCM translations are provided.
Interface options such as serial and parallel inputs and outputs, along with hardware
and microprocessor control modes, are provided by the integrated circuits. Up to 14
separate ADPCM algorithms are available in any given configuration on a per-channel
basis.
The Bt8110 requires an external lookup table ROM. The Bt8110B has an internal
lookup table ROM, or can use an external lookup table ROM. When in direct framer
interface mode, transparent channels in the Bt8110 will operate at 56 kbit/s; the
Bt8110B operates at 64 kbit/s. A hardware control, direct framer interface mode has
been added to the Bt8110B. For more details on the Bt8110B mode controls, refer to
Table 1-1 and Tab le 1- 4.
Functional Block Diagram
64 Kbit/s
PCM
Input
32 Kbit/s
ADPCM
Input
Convert to
Uniform
PCM
ENCODER
Inverse
Adaptive
Quantizer
DECODER
Input
Signal
Quantized
Difference
Signal
Difference
+
+
–
Signal
Estimate
Reconstructed
+
+
–
Signal
Estimate
Adaptive
Predictor
Signal
Adaptive
Predictor
Signal
Adaptive
Quantizer
Reconstructed
Signal
Quantized
Difference Signal
Convert to
PCM
+
Quantizer
Synchronous
Coding
Adjustment
32 Kbit/s
ADPCM
Output
Inverse
Adaptive
64 Kbit/s
PCM
Output
Distinguishing Features
• Bt8110B offers internal ROM
• 24 or 32 full-duplex channel capacity
(48 or 64 channels with two
processors)
• 2-, 3-, 4- and 5-bit quantization
dynamically selectable on a
channel-by-channel, frame-by-frame
basis
• Transparent channel operation
• Two control modes available:
microprocessor and hardware.
• Direct framer interface for both T1
and E1 signal formats
• Supports the optimal RESET function
described in the algorithm standards
• Supports even-bit inversion of A-law
inputs and outputs (required by
ITU-T Recommendations G.726, and
G.727)
• Minimum throughput delay
• Pin compatible with Bt8110
• 8 mw per-channel, low-power CMOS
Applicable Standards
• ANSI T1.302-1987
• ANSI T1.303-1989
• ANSI T1.310-1991
• ITU-T G.726, G.727
• ANSI T1.501-1994
• ANSI T1Y1 Technical Reports #3 and
#10
Applications
• T1/E1 Transcoders
• T1/E1 Multiplexers
• Personal Communications Systems:
Digital European Cordless
Telecommunications (DECT),
Personal Access Communications
System (PACS)
• Wireless Local Loop
• Voice PairGain
• DCME Systems
• Speech Processing/Recording
• Voice Mail/Packetization
• Voice over ATM/Frame Relay
Data Sheet100060C
January 2000
Ordering Information
Model NumberPackageAmbient Temperature Range
Bt8110EPJ68-Pin Plastic Leaded Chip Carrier (PLCC)–40 °C to +85 °C
Bt8110EPJB68-Pin Plastic Leaded Chip Carrier (PLCC)–40 °C to +85 °C
Revision History
RevisionLevelDateDescription
AAdvancedCreated
BDecember 1996
CJanuary 2000The timing diagrams for the following figures have been
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The Adaptive Differential Pulse Code Modulation (ADPCM) algorithm is a
transcoding operation which consists of encoding 64 kbit/s Pulse Code
Modulation (PCM) to 16, 24, 32, or 40 kbit/s ADPCM and decoding from
ADPCM to 64 kbit/s PCM. The multichannel processor provides transcoding for
both A-law and
channel-by-channel basis.
The Bt8110/8110B has a maximum capacity of 64 channels of ADPCM
operations. It can be configured to provide 24 or 32 full-duplex channels
providing both encoding and decoding. It can also be configured to provide 48 or
64 half-duplex channels providing either encoding or decoding. The
Bt8110/8110B consists of a VLSI CMOS integrated circuit and a ROM.
NOTE: In the Bt8110, the ROM is external. Additionally, for the Bt8110, a 64 K
ROM will provide six different ADPCM codes, while a 128 K ROM will
provide 14 different ADPCM codes. (See Table 3-1.). The Bt8110B has an
internal ROM or can be used with the external ROM. The Bt8110B’s
internal ROM contains 14 different ADPCM codes (see Tabl e 3- 2),
µ-law PCM codes. The PCM coding rate is selectable on a
Two Bt8110/8110Bs and a single ROM can be configured to provide 48 or 64
full-duplex channels for operation in transcoding applications. There are two
control modes for the Bt8110/8110B: Hardware and Microprocessor. The
hardware mode provides for input of code selection, transparency selection,
algorithm reset, and PCM coding law on a per-channel basis. The microprocessor
mode is provided via an integral interface to a microprocessor consisting of a
microprocessor, program and data memory, and desired status indicators.
100060CConexant1-1
1.0 Product DescriptionBt8110/8110B
1.1 Channel Capacity and Configuration ModesHigh-Capacity ADPCM Processor
1.1 Channel Capacity and Configuration Modes
There are four configurations for the operational mode of the Bt8110/8110B (see
Table 1 -1 ). These configurations are established by setting the three mode control
bits ([MODE[2:0]) and the enable framer bit [EN_FRMR] in the Mode Control
Register [mode; 0x40], in the microprocessor mode or on signal pins in the
hardware mode (AD[2:0] and CTRL[0]). Table 1-1 summarizes the
configurations and the input code applied to each.
Table 1-1. ADPCM Operational Modes
CTRL
[1]
NOTE(S):
(1)
2. CTRL[1] and CTRL[0] are available only in the Bt8110B.
CTRL
[0]
x0100
x0101Encoder Only6.14448
x0110Decoder Only6.14448
01100Direct Framer Interface12.35224
Interleaved operation means that the Bt8110/8110B alternates between encoder and decoder operation on consecutive
inputs. This requires that the inputs and outputs be interleaved (PCM/ADPCM/PCM, etc.) as well.
Mode
Control
Function
Encoder/Decoder Interleaved
In T1 and E1 direct framer interface modes the Bt8110/8110B can connect
directly to a T1 or E1 framer providing 24 or 32 full-duplex channels of encoding.
These configurations are described in detail in Appendix B and C.
(1)
Clock
Rate
(MHz)
6.144 24
Channel
Capacity
Full-duplex
Half-duplex
Half-duplex
Full-duplex
Clock
Rate
(MHz)
8.19232 Full-duplex
8.19264 Half-duplex
8.19264 Half-duplex
8.19232 Full-duplex
1.1.1 Signal Inputs and Outputs
Channel
Capacity
The Bt8110/8110B provides both parallel and serial inputs and outputs. The 8-bit
parallel inputs are selected by setting the input PSIGEN high. The serial input is a
multiplexed encoder/decoder input to provide interleaved signals. The transfer
rate of the serial input and output is one-half the input clock rate (CLOCK). The
serial output is also multiplexed in interleaved encoder/decoder operation.
ADPCM inputs and outputs appear on the most significant bits.
The serial signal input and output words are 8 bits, with the most signif icant
bit (sign bit for PCM) appearing first. When transparent operation is selected for
a given channel for either an encoder or a decoder, all 8 bits are transferred
without modification from the input to both the serial and parallel outputs.
NOTE: The exception is with the Bt8110 when the parallel interface is selected in
the direct T1/E1 framer interface mode; then the decoder path PSIG[0]
must held at a logic low level.
1-2Conexant100060C
Bt8110/8110B1.0 Product Description
High-Capacity ADPCM Processor
1.1.2 Embedded Coding
The Bt8110/8110B has the capability to provide embedded coding according to
ANSI Standard T1.310-1991 and ITU-T Recommendation G.727. This coding
technique allows the encoding to be performed with 5 bits of encoding
information, and the decoding to be done with anywhere from 2 to 5 input bits.
The coding algorithm is defined so that although the coding distortion increases
as the number of bits at the decoder decreases, the encoder and the decoder will
remain synchronized.
ROM code selected. Along with four different standard (non-embedded) ADPCM
codes, two embedded codes can be provided with a 64 K ROM and up to six
different embedded codes, with eight different standard (non-embedded) codes,
can be provided with a 128 K ROM. The encoder always provides the maximum
number of bits (up to 5) defined by the code selected. The decoder requires up to
5 ADPCM bits and a 2-bit encoded input that indicates how many bits are present
at the decoder input. This input signal is applied to bits 1 and 2 of the parallel
input bus. If embedded coding is not in use, bits 1 and 2 should be connected to
ground.
1.1.3 Control Mode
1.1 Channel Capacity and Configuration Modes
The Bt8110/8110B is designed so that embedded coding is enabled by the
Each channel has four sets of per-channel control inputs. These are for selecting
the PCM coding law (A-law or
the RESET function of the ADPCM coding algorithm, and selecting which of 14
codes (six codes for a 64 K ROM) is used for encoding or decoding.
The microprocessor mode is selected by setting input MICREN high. The
microprocessor can address 65 different registers. There is a control register for
each of the encoder and decoder channel operations and a mode control register
that sets the operating mode of the Bt8110/8110B.
The Bt8110 and Bt8110B are packaged as 68-pin Plastic Leaded Chip Carriers
(PLCCs). Figures 1-1 and 1-2 illustrate the pinouts for the Bt8110 and Bt8110B,
respectively. Pin assignments are listed in numerical order in Table 1 -2 for
Bt8110, and in Tab le 1 -3 for Bt8110B. Figures 1-2 and 1-4 show the functionally
partitioned logic diagrams for Bt8110 and Bt8110B. Pin descriptions, names, and
I/O assignments are detailed in Table 1-2.
Parallel Signal In 6
Parallel Signal In 5
Parallel Signal In 4
Parallel Signal In 3
Parallel Signal In 2 IPSIG[2]
Parallel Signal In 1
Parallel Signal In 0
Parallel Signal In 6
Parallel Signal In 5
Parallel Signal In 4
Parallel Signal In 3
Parallel Signal In 2 IPSIG[2]
Parallel Signal In 1
Parallel Signal In 0
Table 1-4. Bt8110/8110B Hardware Signal Definitions (1 of 2)
Pin LabelSignal NameI/ODefinition
CLOCKClockIThe system clock provided to the Bt8110/8110B. Maximum clock
frequency is 16.5 MHz, and it must have minimum high and low
periods of 27 ns (duty cycle of 45% to 55% at 16.5 MHz, or 22%
to 78% at 8.192 MHz).
SYNCSynchronization IProvides input and output synchronization.
(1)
RESET
ADPCM_STBADPCM StrobeOActive when the parallel ADPCM inputs and outputs are enabled in
PCM_STBPCM Strobe OActive when the parallel PCM inputs and outputs are enabled in
Clock I and Serial Interface
SERIAL_INSerial Data Input IThis pin has multiplexed PCM and ADPCM signals in interleaved
ResetISelects the algorithm reset function per ANSI T1.303-1989 and
ITU-T G.726.
interleaved mode, and is active for both PCM inputs and ADPCM
outputs in encoder mode. This pin is disabled in decoder mode.
interleaved mode, and is active for both ADPCM inputs and PCM
outputs in decoder mode. This pin is disabled in encoder mode.
mode; PCM signals for encoder mode, and ADPCM signals for
decoder mode.
SERIAL_OUTSerial Data Output OThis pin has multiplexed PCM and ADPCM signals in interleaved
mode; ADPCM signals for encoder mode, and PCM signals for
decoder mode.
PSIGENParallel Signal EnableIA control signal that enables parallel inputs. Does not affect parallel
outputs (D[7:0]), which are always available. On the Bt8110B, this
signal has extra functionality (see note in Section 2.2.1.1).
PSIG[7:0]Parallel Signal Input IThe parallel input data bus. The most significant bit (sign bit for
PCM, I1 for ADPCM) appears on PSIG[7]. This input bus is also
used to indicate ADPCM word length when embedded decoding is
performed. When serial inputs are used, these inputs should be left
unconnected (internal pull-down resistors included) except as
required for embedded decoding.
Parallel Interface
D[7:0]Parallel Signal Output/
ROM Data Input
Microprocessor Interface
MICREN
(1)
CS
(1)
WR*
(1)
ALE
(1)
Microprocessor Enable IActive high input that selects per-channel control via a
Chip SelectIActive high input that enables write operations to the
Write*IActive low input that performs the write operation to the
µP Address Latch
Enable.
I/OOn the Bt8110, these signals are inputs, accepting data from the
external lookup table ROM. The data on these pins also provides
parallel PCM and ADPCM output functionality for the Bt8110. On
the Bt8110B, these signals are outputs when internal ROM is used.
D[7] is the most significant bit of the PCM and ADPCM data.
microprocessor interface.
Bt8110/8110B. In hardware mode this pin enables transparent
operation.
Bt8110/8110B. In hardware mode this pin enables A-law PCM
coding (low for µ-law).
IALE is a microprocessor-generated signal that causes the
Bt8110/8110B to latch in the address on the address/data bus. ALE
is active high with the address being latched on the falling edge of
the signal. In hardware mode this pin becomes an optional code
input.
AD[6:0]µP Address/Data BusIMicroprocessor 7-bit address and data bus.
1-10Conexant100060C
Bt8110/8110B1.0 Product Description
High-Capacity ADPCM Processor
Table 1-4. Bt8110/8110B Hardware Signal Definitions (2 of 2)
Pin LabelSignal NameI/ODefinition
A[13:0]ROM Address Bus I/OOn the Bt8110, these signals are ouputs driving the address lines
on the external lookup table ROM. On the Bt8110B, A[7:0] are
inputs when internal lookup table ROM is used. A[13:8] must be
left open when using the Bt8110B with internal lookup table ROM
enabled.
using Bt8110B with internal lookup table ROM enabled.
enabled, A[0] and A[3] have the following functions:
•A[0] Disable G.726 TR predictor reset. This function forces the
•A[3] Disable even-bit inversion in A-law. This function disables
•A[2:0], A[5:4] are used to allow the Bt8110B to be compatible
•A[7:6] are factory test pins on the Bt8110B that must always
ROM Interface
CTRL[1,0]Control InputsIOn the Bt8110B two new control inputs are provided in place of
Vcc and GND. CTRL[1] (pin 39) is Vcc in the Bt8110, and CTRL[0]
is GND in Bt8110.
1.2 Pin Descriptions
A[7:0] may be left open or held low for normal operation when
When using the Bt8110B with internal lookup table ROM
output TD of block TONE to a value of 0.
even-bit inversion per G.711.
Signal A[0] will be sampled at the same input times as the
code select inputs, and so “disable predict or reset” can be
controlled on a channel-by-channel bases. A[3] is not timed
and so it affects every channel.
with pre-Bt8110 designs.
be open or held at logic low level.
The modes that these new control inputs implement are:
CTRL[1]CTRL[0]Mode
lowlowInternal ROM only, interleaved,
encode only & decode only modes
lowhighInternal ROM only, direct framer
interface. This option provides a
hardware-mode direct framer
interface.
highlowBt8110–compatible mode, external
ROM required
highhighNot used (production test only)
In Bt8110-compatible mode, existing ROMS will work.
V
CC
GNDGroundINine pins are provided for ground on the Bt8110. Eight pins are
Supply Voltage
SESE Parameter OThe serial output pin for the SE parameter. Used only for factory
TDPTDP Parameter OThe serial output pin for the TDP parameter. Used only for factory
Test Signals
YY Parameter OThe serial output pin for the Y parameter. Used only for factory test
SupplyISeven pins are provided for supply voltage on the Bt8110. Six pins
are provided on the Bt8110B.
provided on the Bt8110B.
test purposes and should be left unconnected.
test purposes and should be left unconnected.
purposes and should be left unconnected.
NOTE(S):
(1)
All inputs are active high except WR* which adapts to the type of microprocessor being used. See Section 2.1.2.
100060CConexant1-11
1.0 Product DescriptionBt8110/8110B
1.2 Pin DescriptionsHigh-Capacity ADPCM Processor
1-12Conexant100060C
2
2.0 Functional Description
2.1 Overview
Figure 2-1 and Figure 2-2 illustrate block diagrams for Bt8110 and Bt8110B,
respectively. The quantizer and reconstruction tables are stored in the external
(Bt8110) or internal (Bt8110B) ROM that holds the fixed parameter values and
lookup tables specified in the ADPCM algorithms. Both the encoder and decoder
paths through the ADPCM processor provide the conversion of a 64-kbps µ-law
or A-law PCM channel to and from a 16-, 24-, 32-, or 40-kbit/s ADPCM channel.
The logic is arranged in a serial architecture to take full advantage of time
sharing of common circuitry. In the encoder path, prior to the conversion of the
PCM input to uniform PCM, a difference signal is obtained by subtracting an
estimate of the input signal from the input signal itself. An adaptive 3-, 7-, 15-, or
31-level quantizer (or 4-, 8-, or 16-level for embedded codes) is used to assign
two, three, four, or five binary digits, respectively, to the value of the difference
signal for transmission. An inverse quantizer produces a quantized difference
signal from the corresponding binary digits. The signal estimate is added to this
quantized difference signal to produce the reconstructed version of the input
signal. Both the reconstructed signal and the quantized difference signal are
operated upon by an adaptive predictor that produces the estimate of the input
signal, thereby completing the feedback loop.
The decoder path includes a structure identical to the feedback portion of the
encoder, together with a uniform PCM to µ-law or A-law conversion and
synchronous coding adjustment. The synchronous coding adjustment prevents
cumulative distortion occurring on synchronous tandem codings
(ADPCM-PCM-ADPCM... digital connections) under certain conditions. The
synchronous coding adjustment is achieved by adjusting the PCM output codes in
a manner that eliminates quantizing distortion in the next ADPCM encoding
stage.
100060CConexant2-1
2.0 Functional DescriptionBt8110/8110B
2.1 OverviewHigh-Capacity ADPCM Processor
Figure 2-1. Bt8110 Block Diagram
SYNC
SERIAL_IN
SERIAL_OUT
CLOCK
PSIG[7:0]
ALE, CS,
MICREN
AD[6:0]
Figure 2-2. Bt8110B Block Diagram
Serial
Processor
Parallel
Processor
Microprocessor
Interface
Memory
Control
Quantizer
Adjustment
Memory
Quantizer
Signal
Memory
Predictor
Weight
Memory
Parallel Signal Output
D[7:0]
A[13:0]
Reconstruction
and Quantizer
Table Memory
ADPCM_STB
PCM_STB
100060_006
SYNC
SERIAL_IN
SERIAL_OUT
CLOCK
PSIG[7:0]
ALE, CS,
MICREN
AD[6:0]
Serial
Processor
Parallel
Processor
Microprocessor
Interface
Memory
Control
Quantizer
Adjustment
Memory
Quantizer
Signal
Memory
Predictor
Weight
Memory
Reconstruction
and Quantizer
Table Memory
D[7:0]
Parallel Signal
Output
ADPCM_STB
PCM_STB
100060_007
2-2Conexant100060C
Bt8110/8110B2.0 Functional Description
High-Capacity ADPCM Processor
2.1.1 Clocking and Synchronization
Each operating mode of the Bt8110/8110B requires clock and synchronization
inputs to allow proper operation. If the microprocessor mode is used, then the
synchronization signal frequency can be any submultiple of a PCM frame
(8 kHz). If the hardware mode is used, then the synchronization frequency can be
any submultiple of 1/32 of the clock frequency; in this case the synchronization
signal is used to identify consecutive inputs and outputs.
The CLOCK signal must operate at a frequency of 8.192 MHz to obtain the
8 kHz frame rate for PCM signals. This clock can be gapped and may have a peak
rate of 16.5 MHz (maximum rate of 16.384 MHz is used in the E1 transcoder
application).
The SYNC signal must operate at a submultiple of the 8 kHz frame rate. The
SYNC signal is active on the falling edge; the rising edge can occur anywhere in
the frame. (In direct framer interface mode, the SYNC signal is active on the
rising edge.) The SYNC signal synchronizes internal modulo-32 counters and an
internal word counter. Its falling edge synchronizes the counters, and this can
occur at any submultiple of 8 kHz.
ADPCM_STB and PCM_STB are output timing signals that can be used to
enable three-state inputs to the parallel input bus and to clock the parallel output
bus signals. They are each low for two clock cycles. The rising edge of each
signal can be used to clock the parallel output data into an octal register.
2.1 Overview
2.1.2 Microprocessor Interface
An integral control interface to an Intel 8051-family microprocessor, Motorola
68HC11-family, or equivalent is provided. This microprocessor interface allows
the operation mode and the per-channel configuration of the Bt8110/8110B to be
selected directly from a software-based system. The use of this interface is
optional; it is enabled by setting the MICREN control input high. When MICREN
is set high, all mode and per-channel configuration is done through the
microprocessor. The microprocessor being used should be connected as shown in
Table 2 -1 .
The microprocessor interface to the Bt8110/8110B consists of 11 pins: µP
enable (MICREN) address latch enable (ALE), write enable (WR*), chip select
(CS), and seven multiplexed address/data bits (AD[6:0]). These signals are
connected as shown in Tabl e 2-1 .
The microprocessor interface is designed to allow the direct connection of an
Intel 8051-family or Motorola 68HC11 microprocessor. The chip select input can
be taken from one of the address inputs or from an address decoding circuit to
locate the Bt8110/8110B within any desired memory address range. The chip
select input to the Bt8110/8110B allows the control of multiple circuits from a
single microprocessor.
The microprocessor interface is write-only. Data read from the address space
of the Bt8110/8110B will be invalid.
100060CConexant2-3
2.0 Functional DescriptionBt8110/8110B
2.1 OverviewHigh-Capacity ADPCM Processor
Table 2-1. Signal Connections
Bt8110/8110B
Pin
MICREN
ALEAddress Latch EnableALEAS
WR*Write EnableWR*E
CSChip SelectA[n]A[n]
AD[0]Address/DataAD[0]AD[0]
AD[1]Address/DataAD[1]AD[1]
AD[2]Address/DataAD[2]AD[2]
AD[3]Address/DataAD[3]AD[3]
AD[4]Address/DataAD[4]AD[4]
AD[5]Address/DataAD[5]AD[5]
AD[6]Address/DataAD[6]AD[6]
The interface for the Intel 8051 or Motorola 68HC11 microprocessors
comprises the latch enable signal, the write enable (8051) or enable signal
(68HC11), the chip select signal (one pin from port P2 of the 8051) and the seven
low bits of the 8-bit address/data bus (port P0 of the 8051). For the 68HC11
microprocessor, the enable signal E is connected to the write enable pin. The
setup and hold times required for the latch enable and write enable signals are
10 ns. Other (much faster) processors can be used as long as the multiplexed
address/data bus feature of the 8051 is supported.
Detailed timing requirements for the microprocessor interface are given in
Section 4.1.
FunctionIntel 8051Motorola 68HC11
µPEnable
V
CC
V
CC
2.1.3 Address Map
The address map for the controller is given in the Register Summary, Tabl e 3-3
and Tab le 3 -4 , where both interleaved and encoder/decoder operations are shown.
The internal control registers for the 32 encoders and the 32 decoders for
interleaved operation are located at addresses 0x00–0x3F. A write to address 0x40
will load the Mode Control Register [mode; 0x40].
2-4Conexant100060C
Bt8110/8110B2.0 Functional Description
High-Capacity ADPCM Processor
2.2 Modes of Operation
This section details the functional timing of the clock, synchronization, and signal
interfaces. The data and control interfaces include the clock and synchronization
inputs, the PCM and ADPCM inputs and outputs, and the control inputs to select
algorithm reset, transparent operation, PCM code type, and the selected coding
algorithm when the microprocessor interface is not selected. The 24- or
32-channel full-duplex interleaved encoder and decoder operation is presented
first, followed by 48- or 64-channel encoder-only operation, and 48- or
64-channel decoder-only operation.
2.2.1 24- or 32-Channel Full-Duplex Interleaved Operation
Figure 2-3 illustrates the operation of the Bt8110/8110B in 24- or 32-channel
full-duplex interleaved mode with microprocessor control. The channel numbers
in parentheses are for the 24-channel full-duplex mode. In this diagram, inputs
are shown changing on negative edges of the input clock, and outputs are shown
changing on positive edges. This is the recommended method for operating the
Bt8110/8110B to avoid any timing problems. Detailed timing parameters are
given in Chapter 4.0.
To operate the Bt8110/8110B in the 24- or 32-channel full-duplex interleaved
mode, the Mode Control Register located at address 0x40 should be set to a value
of 0x0C for 32 channels, 0x04 for 24 channels.
In many 24-channel configurations, a gapped clock will be used to account for
the frame bit of the T1 signal; this operates correctly as long as there are exactly
32 clock cycles per channel processed.
2.2 Modes of Operation
100060CConexant2-5
2.0 Functional DescriptionBt8110/8110B
2.2 Modes of OperationHigh-Capacity ADPCM Processor
Figure 2-3. Input and Output Timing for 24- or 32-Channel Full-Duplex Interleaved Operation (Microprocessor Control)
Either serial or parallel signal inputs can be used in all modes. When the PSIGEN
input is tied high, the parallel signal inputs for both PCM and ADPCM are
enabled.
The SERIAL_IN signal contains the serial PCM encoder input, sign bit first,
and the serial ADPCM input. (The ADPCM values are preceded by I with I1
being the most significant bit.) The input is applied at a rate of 4.096 Mbit/s
(3.072 Mbit/s for 24-channel). The timing is arranged as shown so that the middle
of bit 3 of the ADPCM is coincident with falling edges of SYNC. For codes of
less than 5 bits, the unused serial input ADPCM bits must be set to zero.
The PSIG[7:0] signal is used for the signal input when PSIGEN is high. It is
also used for the ADPCM word length indication when embedded decoding is
performed. Table 2 -2 is the arrangement of the input bits on the bus.
NOTE: On the Bt8110B only, a latch has been added to the parallel input signal
enable, PSIGEN. This signal now has the same input timing as the parallel
input itself. This allows different inputs for the encoder and decoder,
respectively, in interleaved mode, and using the serial input for idle code
insertion under control of PSIGEN when the normal input is parallel
mode, or vice versa.
2-6Conexant100060C
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