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Hardware Configuration
The DIT4192 input serial port supports Left Justified and I
2
S formatted PCM data from the PCM4222
audio serial port. The TDM data formats are not supported by the DIT4192 input serial port. The DITFMT
element on switch SW3 is used to select the proper data format for the DIT4192, and must match the data
format that is selected using the FMT0 and FMT1 elements on switch SW3.
summarizes the
operation for and relationship between the DIT4192 and PCM4222 data format switches.
Table 16. DIT4192 Data Format Selection
Switch SW3, FMT1
Switch SW3, FMT0
Switch SW3, DITFMT
Audio Data Format
LO
LO
LO
Left Justified
LO
HI
HI
I
2
S
HI
X
X
TDM formats are not supported
Although one DIT4192 transmitter supports transmission of two-channels of PCM audio data at
sampling/frame rates up to and including 216kHz, it is sometimes desirable to use two DIT4192 devices,
each carrying data for only a single channel (left or right, respectively) at a frame rate equal to one-half the
PCM4222 output sampling rate. This is referred to as Single-Channel, Double Sampling Frequency
transmission in the AES3-2003 standard. The DIT4192 Mono mode is used to implement this form of
transmission.
Mono mode is enabled or disabled using the MONO input (pin 21) of the DIT4192 transmitters. The
DITMONO element on switch SW3 is used to control the MONO pin.
demonstrates the operation
of the DITMONO switch.
Table 17. DIT4192 Transmission Mode Configuration
Switch SW3, DITMONO
DIT4192 Transmission Mode
LO
Two-channel
HI
Single-Channel Double Sampling Frequency
The MDAT input (pin 20) of the DIT4192 transmitters is used to select left or right channel for transmission
in Mono mode. The MDAT pin of transmitter U13 is connected to ground, selecting the left input channel.
The MDAT pin of transmitter U14 is connected to VDD, selecting the right input channel. In Mono mode,
the left channel is transmitted from AES3 Output #1 (connectors J7 and J8), while the right channel is
transmitted on AES3 Output #2 (connectors J9 and J10).
When Mono mode is disabled, both the left and right channels are output on both AES3 Output #1 and #2.
This allows for simultaneous balanced and unbalanced transmission of the AES3-encoded output data.
Mono Mode Example: Assume that you are transmitting 192kHz two-channel data using the AES3
transmitters, with a 24.576MHz master clock and the clock dividers set to divide by 128. By simply
enabling Mono mode (setting the DITMONO switch to HI), the transmission converts to Single-Channel,
Double Sampling Frequency mode with an output frame rate equal to 96kHz. There is no need to change
the master clock divider or frequency, because the DIT4192 manages the change in output frame rate
automatically.
PCM4222EVM User's Guide
14
SBAU124 – December 2006