GS1670 datasheet(73/126 Pages) SEMTECH

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GS1670 HD/SD SDI Receiver

Data Sheet

53831 - 2

September 2012

73 of 126

4.18.3.6.1 Audio Channel Status Read

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

GS1670 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 set, and acquisition stops. The ACS data is overwritten with new data when the

ACS_DET bit is cleared in the system.

4.18.3.6.2 Audio Channel Status Regeneration

When the ACS_REGEN bit in the host interface 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;

• Set the ACS_REGEN bit to logic HIGH

• Write the desired ACSR data to the ACSR registers

• 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[A:D]

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 4-23:Audio Channel Status Information Registers

Name

Description

Default

ACSR[7-0]

Audio channel status block byte 0 set. Used when ACS_REGEN is set HIGH

85h

ACSR[15-8]

Audio channel status block byte 1 set. Used when ACS_REGEN is set HIGH

08h

ACSR[23-16]Audio channel status block byte 2 set. Used when ACS_REGEN is set HIGH

28h (SD) 2Ch (HD)

ACSR[31-24]:

ACSR[183-176]

Audio channel status block data for bytes 3 to 22. Used when ACS_REGEN is set HIGH

00h

ACS_REGEN

Audio channel status regenerate

ACS_APPLY

Apply new ACSR data

ACS_APPLY_W

AIT[A:D]

Waiting to apply new ACSR data

ACS[7-0]:

ACS[183-176]

Audio channel status block data for bytes 0 to 22

00h: 00h

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