GS3470 datasheet(83/169 Pages) SEMTECH

83 / 169 page

GS3470

Final Data Sheet

Rev.8

PDS-060500

September 2017

83 of 169

Semtech

www.semtech.com

4.19.3.6 Audio Channel Status

The GS3470 detects the AES/EBU Audio Channel Status (ACS) block information for each

of the selected channel pairs.

ACS data detection is indicated by corresponding ACS_DET flag bits in the DBN_ERR

4.19.3.7 Audio Channel Status Read

AES/EBU ACS data is available separately for each of the channels in a stereo pair. The

GS3470 defaults to reading the first channel of each pair. There are 184 bits in each ACS

packet, which are written to twelve 16-bit right-justified registers in the host interface.

The ACS_USE_SECOND bit (default LOW) selects the second channel in each audio pair

when set HIGH.

Once all of the ACS data for a channel has been acquired, the corresponding ACS_DET

bit is asserted, and acquisition stops. The ACS data is overwritten with new data when

the ACS_DET bit is cleared in the system.

4.19.3.7.1 Audio Channel Status Regeneration

When the ACS_REGEN bit in the REGEN register is set HIGH, the audio de-embedder

embeds the 24 bytes of the Audio Channel Status information programmed in the

ACSR[183:0] registers into the 'C' bit of the AES/EBU outputs. The same Audio Channel

Status information is used for all output channels.

In order to apply ACSR data:

1. Set the ACS_REGEN bit to logic HIGH

2. Write the desired ACSR data to the ACSR registers

3. Set the ACS_APPLY bit to HIGH

At the next status boundary, the device outputs the contents of the ACSR registers as

ACS data. This event may occur at a different time for each of the output channels. While

waiting for the status boundary, the device sets the appropriate

ACS_APPLY_WAIT[D:A] flag.

Table 4-23 shows the host interface default settings for the Audio Channel Status block.

The audio de-embedder automatically generates the CRC word.

Table 4-22: Audio Sample Word Lengths

ASWL[D:A]

Audio Sample

Word Length (SD)

Audio Sample

Word Length (HD)

00b

24-bit

24-bit (default)

01b

20-bit

10b

16-bit

11b

Auto 24/20-bit (default)

Reserved

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