Analog Devices ADV7850 Hardware Manual page 364

sent across the TMDS link in the channel status data contained in the Audio Sample packets.
The placement of I2S channels into the Audio Sample subpackets defined in the HDMI specification can be specified in the following
controls:
• SUBPKT0_L_SRC
•
SUBPKT0_R_SRC
• SUBPKT1_L_SRC
•
SUBPKT1_R_SRC
• SUBPKT2_L_SRC
•
SUBPKT2_R_SRC
• SUBPKT3_L_SRC
• SUBPKT3_R_SRC
When these fields are set to their default values, all I2S channels are placed in their respective position (for example, I2S0 left channel in
channel 0 left position, I2S3 right channel in channel 3 right position, and so on) but this mapping is completely programmable if desired.
The ADV7850 Tx core supports the reception of standard I2S, left-justified, right-justified, and direct AES3 stream formats with a sample
word width between 16-bits and 24-bits. The format of the input I2S stream is set via
set via word_length[3:0]. The ADV7850 also supports the reception of an I2S stream in both 64-bit and 32-bit modes, so either 32- or 16-
bit clock (that is, the signal input through SCLK pin) edges or cycles per channel are valid. The ADV7850 will adapt to 32- or 64-bit
modes automatically, and the current mode can be read in i2s_32bit_mode. Refer to
I2S streams input to the ADV7850.
When the ADV7850 is configured to receive a direct AES3 stream, the stream it receives should have IEC60958-like subframes (refer to
Figure 125) with the stream formatted as follows:
• Data should be aligned as shown in
• Preamble left out as shown in
• Parity bit is replaced by the block start flag. The ADV7850 automatically computes the parity bit.
The channel status data collected from audio stream input to the pin aud_in[0] is used in the Audio Sample packets sent by the ADV7850
to the downstream sink. The channel status data can alternatively be programmed by setting cs_bit_override. When
to 1, setting ext_audiosf_sel
channel status data is extracted from the audio stream input to I2S0. The sampling frequency is set via i2s_sf[3:0].
Note: All four stereo channels (aud_in[3:0]) are enabled by setting
only is needed, the I2S audio stream data must be input to aud_in[0].
When ext_audiosf_sel is set to 1, the audio sampling frequency programmed via I2S_SF is used for the determination of the pixel
repetition factor.
audioif_sf[2:0], Addr B8 (Main), Address 0x74[4:2]
This control is used to set the audio sampling frequency in the InfoFrame. It should be set to 0, except for SACD.
Function
audioif_sf[2:0]
000 
audioif_cc[2:0], Addr B8 (Main), Address 0x73[2:0]
This control is used to select the audio InfoFrame channel count.
Rev. A May 2012
Figure 125.
Figure 126.
allows the programming of the audio sampling frequency used for the channel status bits while all other
Description
Default
i2sformat[1:0]
Figure 127
i2senable[3:0] to 0xF and audioif_cc[2:0]
i2senable[3:0] and audioif_cc[2:0]
364
while the audio sample word width is
to Figure 131 for timing diagrams for the
cs_bit_override
to 0x7. If one stereo channel
must be set to 1.
ADV7850
is set