adau1442 Analog Devices, Inc., adau1442 Datasheet - Page 16

• Manufacturer Part Number: adau1442
• Description: Sigmadsp Digital Audio Processor With Flexible Audio Routing Matrix
• Manufacturer: Analog Devices, Inc.

OVERVIEW
The ADAU144x is a 24-channel audio DSP with an integrated
S/PDIF receiver and transmitter, flexible serial audio ports, up
to 16 channels of asynchronous sample rate converters (ASRCs),
flexible audio routing, and user interface capabilities. Signal
processing capabilities include equalization, crossover, bass
enhancement, multiband dynamics processing, delay compen­
sation, speaker compensation, and stereo image widening.
These algorithms can be used to compensate for the real-world
limitations of speakers, amplifiers, and listening environments,
resulting in an improvement in perceived audio quality.
An on-board oscillator can be connected to an external crystal
to generate the master clock. A phase-locked loop (PLL) allows
the ADAU144x to be clocked from a variety of clock frequencies.
The PLL can accept inputs of 64 × f
or 512 × f
where f
mode. In dual or quad rate mode, these multipliers are halved
or quartered, respectively. System sample rates include, but are
not limited to, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, and 192 kHz.
The ADAU144x operates from a 1.8 V digital power supply and
a 3.3 V analog supply. An on-board voltage regulator can be used
to operate the chip from a single 3.3 V supply.
The ADAU144x has a sophisticated control port that supports
complete read and write capability of all memory locations,
excluding read-only addresses. Control registers are provided to
offer complete control of the chip’s configuration and serial modes.
Handshaking is included for ease of memory uploads and down­
loads. The ADAU144x can be configured for either SPI or I
control. Program RAM, parameter RAM, and register contents
can be saved in an external EEPROM, from which the ADAU144x
can self-boot on startup.
The ADAU144x serial ports operate with digital audio I/Os in
the I
The flexible serial data ports allow for direct interconnection to
a variety of ADCs, DACs, and general-purpose DSPs. The
combination of an on-board S/PDIF transmitter and receiver
and 16 channels of ASRCs. allows for easy compatibility with an
extensive number of external devices, and a system with up to
nine sampling rates.
The flexible audio routing matrix (FARM) is a system of
multiplexers used to distribute the audio signals in the
ADAU144x among the serial inputs and outputs, audio core,
and ASRCs. FARM can easily be configured by setting the
appropriate registers.
Within the ADAU144x family, there are three devices, each
distinguished by the number of on-board ASRCs and maximum
sample rates. The ADAU1442 contains eight 2-channel ASRCs, the
ADAU1445 contains two 8-channel ASRCs, and the ADAU1446
has no ASRCs.
Two sets of serial ports at the input and output can operate in a
special flexible TDM mode, which allows the user to independently
2
S, left-justified, right-justified, or TDM-compatible modes.
S
is the sampling rate of audio in normal-rate processing
S
to generate the internal master clock of the core,
S
, 128 × f
S
, 256 × f
S
, 384 × f
2
Rev. PrA | Page 16 of 92
C
S
,
assign byte-specific locations to audio streams at varying bit
depths. This mode ensures compatibility with codecs using
similar flexible TDM streams.
The core of the ADAU144x is a 28-bit DSP (or a 56-bit when
using double precision mode) optimized for audio processing,
and it can process audio at sample rates of up to 192 kHz. The
program and parameter RAMs can be loaded with a custom
audio processing signal flow built with the SigmaStudio
graphical programming software from Analog Devices, Inc..
The values stored in the parameter RAM control individual
signal processing blocks, such as IIR and FIR equalization
filters, dynamics processors, audio delays, and mixer levels. A
software safeload feature allows for transparent parameter
updates and prevents clicks on the output signals.
Reliability features such as a CRC and program counter
watchdog help ensure that the system can detect and recover
from any errors related to memory corruption.
S/PDIF signals can be routed through an ASRC for processing
in the DSP, or can be sent directly to output on MP pins for
recovery of the embedded audio signal. Other components of
the embedded signal, including status and user bits, are not lost
and can be output on the MP pins as well.
Multipurpose (MP) pins are available for providing a simple
user interface without the need for an external microcontroller.
Twelve pins are available to input external control signals and
output flags or controls to other devices in the system. Four of
these can alternatively be assigned to an auxiliary ADC for use
with analog controls such as potentiometers or system voltages.
As inputs, MP pins can be connected to push buttons, switches,
rotary encoders, potentiometers, or other external control circuitry
to control the internal signal processing program. When con­
figured as outputs, these pins can be used to drive LEDs (with a
buffer), to output flags to a microcontroller, control other ICs, or
to connect to other external circuitry in an application.
The SigmaStudio software is used to program and control the
ADAU144x through the control port. Along with designing and
tuning a signal flow, the software can configure all of the DSP
registers in real time and download a new program and parameter
into the external self-boot EEPROM. SigmaStudio’s easy-to-use
graphical interface allows anyone with audio processing knowledge
to easily design a DSP signal flow and port it to a target application
without the need for writing line-level code. At the same time,
the software provides enough flexibility and programmability
for an experienced DSP programmer to have in-depth control
of the design. In SigmaStudio, the user can add signal processing
cells from the library by dragging and dropping cells, connect
them together in a flow, compile the design, and load the program
and parameter files into the ADAU144x memory through the
control port. The complicated tasks of linking, compiling, and
downloading the project are all handled automatically by the
software.