adau1442 Analog Devices, Inc., adau1442 Datasheet - Page 64

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

S/PDIF RECEIVER AND TRANSMITTER
The ADAU144x features a set of on-chip S/PDIF data ports,
which can be wired directly to transmitters and receivers for
easy interfacing to other S/PDIF-compatible equipment.
S/PDIF Receiver
The S/PDIF input port is designed to accept both TTL and
bipolar signals, provided there is an ac-coupling capacitor on
the input pin of the chip. Since the S/PDIF input data will most
likely be asynchronous to the DSP core, it has to be routed
through an ASRC.
The S/PDIF ports work with sampling rates between 32 kHz
and 108 kHz.
S/PDIF streams contain more than just audio data, including
user data, channel status, validity bit, virtual LRCLK, and block
start. The receiver decodes audio data and sends it to the ASRCs
and DSP core, but the remaining data passes through directly to
the transmitter. This ensures that any user data is unaltered at
the output and is reintegrated into the audio stream.
In the ADAU144x, clock recovery is entirely digital. As a result,
the ADAU144x has better protection against clock jitter.
The ADAU144x S/PDIF ports were designed to meet the
following AES and EBU specifications: a jitter of 0.25 UI p-p at
8 kHz and above, a jitter of 10 UI p-p below 200 Hz, and a
minimum signal voltage of 200 mV.
To transmit data, the S/PDIF output must be turned on. This is
accomplished by writing an activation bit to the S/PDIF
transmitter on/off register. More information can be found in
the Enable S/PDIF to I
2
S Output section and the S/PDIF
SPDIFI
RECEIVER
S/PDIF
Figure 53. S/PDIF Receiver and Transmitter
AUDIO
AUDIO
DATA
AND
Rev. PrA | Page 64 of 92
CONVERTER
DSP CORE
ASRCs
I
2
S
Transmitter—On/Off Switch Register (Address 0xE0C1)
section.
Outputting to the Multipurpose Pins
It is possible to send S/PDIF data from the receiver directly to
output on the MP pins. This mode is activated in Register 0xE241
(see the Enable S/PDIF to I
assignment of signals is shown in Table 50.
Table 50. S/PDIF to MP Pin Assignments
Pin
MP4
MP5
MP6
MP7
MP8
MP9
MP10
MP11
1
There are two groups of signals, each of which can be activated
and deactivated independent from one another. All unused MP
pins function normally.
S/PDIF Transmitter
The S/PDIF transmitter outputs two channels of audio data
directly from the DSP core at the core rate. It does not preserve
or output any additional nonaudio information encoded in the
S/PDIF input stream.
The MP0 to MP3 pins are not applicable and can be used normally.
MP PINS
1
5
TRANSMITTER
BCLK
LRCLK
SDATA
DATA BITS
S/PDIF
Group
2
2
2
2
2
1
1
1
MASTER
MODE
SPDIFO
2
S Output section). The pin
Signal
Validity bit
User data
Channel select
Block start
Virtual LRCLK
SDATA
BCLK
LRCLK