Panasonic EURO 4 Chassis, Technical Manual

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63
20.3. I
2
S Bus Interface
The standardised I
2
S Bus interface allows, for
additional feature processors to be connected to the
MSP3410D
IC2101 , such as the surround processor
for Dolby Pro Logic Processing which is performed
by DPL3520 IC2401 located on the K-Board (ONLY
DOLBY MODELS).
The MSP3410D
IC2101 normally serves as the
master on the I
2
S interface. Here the clock and word
strobe lines are driven by the MSP3410D IC2101 .
The MSP3410D IC2101 can also be switched to
slave mode by software, which sees the lines being
input into the MSP
IC2101 and the master clock
being synchronised to 576 times the I
2
S_WS rate
(32kHz). However in this mode NICAM processing is
not possible.
The I
2
S bus interface consists of five pins:
1. I
2
S_DA_IN1, I2S_DAIN2:
Allows input of 4 channels (2 channels per line,
2 x 16bits) per sampling cycle (32kHz) to be
transmitted.
2. I
2
S_DA_OUT:
Allows for the output of 2 channels (2 x 16bits)
per sampling cycle (32kHz) to be transmitted
3. I
2
S_CL:
Synchronises the transmission of I
2
S serial data
(1.024MHz).
4. I
2
S_WS:
The I
2
S_WS word strobe line defines the data
being transmitted, either the left and right
sample.
The I
2
S Bus has two possible modes of operation
which are described and shown in the timing
diagram below. However only the standard mode of
operation is used.
:
The standard mode: selects the Sony
format, here the I
2
S_WS signal changes at
the word boundaries, this change in the
word strobe signal being used to identify
whether the left or right channel sample is
being transmitted.
:
The second mode: selects the Philips
format, here a change in the I
2
S_WS signal
one I
2
S_CL period before the word
boundaries. Again this change in the word
strobe signal being used to identify whether
the left or right channel sample is being
transmitted.
I2S Bus Timing Diagram
I
2
S_WS
I
2
S_CL
I
2
S_DAIN
I
2
S_DAOUT
16 bit Left channel
16 bit Left channel
16 bit Right channel
16 bit Right channel
Sony Mode
Philips Mode
Sony Mode
Philips Mode
R LSB
L MSB
R MSB
L LSB
R LSB
R LSB
L MSB L LSB
R MSB
R LSB