GS1670 datasheet(55/126 Pages) SEMTECH

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GS1670 HD/SD SDI Receiver

Data Sheet

53831 - 2

September 2012

55 of 126

For any DID or SDID value set to zero, no comparison or match is made. For example, if

the DID is programmed and the SDID is not programmed, the GS1670 only detects a

match to the DID value.

If both DID and SDID values are non-zero, then the received ancillary data type must

match both the DID and SDID before Y/1ANC and/or C/2ANC is set HIGH.

NOTE: SMPTE 352M Payload Identifier packets and Error Detection and Handling

(EDH) Packets are always detected by the GS1670, irrespective of the settings of the

ANC_TYPE registers.

4.16.2 SMPTE 352M Payload Identifier

The GS1670 automatically extracts the SMPTE 352M payload identifier present in the

input data stream for SD and HD. The four word payload identifier packets are written

to VIDEO_FORMAT_X_DS1 and VIDEO_FORMAT_X_DS2 bits accessible through the

host interface.

The device also indicates the version of the payload packet in the VERSION_352M bit of

the DATA_FORMAT_DSX register. When the SMPTE 352M packet is formatted as a

“version 1” packet, the VERSION_352M bit is set HIGH, when the packet is formatted as

a “version 2” packet, this bit is set LOW.

The VIDEO_FORMAT_352_A_X and VIDEO_FORMAT_352_B_X registers are only

updated if there are no checksum errors in the received SMPTE 352M packets.

By default (at power up or after system reset), the VIDEO_FORMAT_X_DS1 and

VIDEO_FORMAT_X_DS2 bits are set to 0, indicating an undefined format.

4.16.2.1 SMPTE 352M Payload Identifier Usage

The SMPTE 352M Payload Identifier is used to confirm the video format identified by the

Automatic Video Standards Detection block (see Section 4.16.4).

4.16.3 Ancillary Data Checksum Error

The GS1670 calculates checksums for all received ancillary data.

These calculated checksums are compared with the received ancillary data checksum

words.

If a mismatch in the calculated and received checksums is detected, then a checksum

error is indicated.

When operating in HD mode, the device makes comparisons on both the Y and C

channels separately. If an error condition in the Y channel is detected, the YCS_ERR bit

in the VIDEO_ERROR_STAT_X register is set HIGH. If an error condition in the C channel

is detected, the CCS_ERR bit in the VIDEO_ERROR_STAT_X register is set HIGH.

When operating in SD mode, only the YCS_ERR bit is set HIGH when checksum errors

are detected.

GS1670 Datasheet(PDF) 55 Page - Semtech Corporation