GS2971 Datasheet, PDF (64/148 Pages) Semtech Corporation – 3Gb/s, HD, SD SDI Receiver, with Integrated Adaptive Cable Equalizer complete with SMPTE Audio and Video Processing

4.16 Video Signal Error Detection & Indication
The GS2971 includes a number of video signal error detection functions. These are
provided to enhance operation of the device when operating in SMPTE mode
(SMPTE_BYPASS = HIGH). These features are not available in the other operating modes
of the device (i.e. when SMPTE_BYPASS = LOW).
Signal errors that can be detected include:
1. TRS errors.
2. HD line based CRC errors.
3. EDH errors.
4. HD line number errors.
5. Video standard errors.
The device maintains an ERROR_STAT_X register. Each error condition has a specific
flag in the ERROR_STAT_X register, which is set HIGH whenever an error condition is
detected.
An ERROR_MASK register is also provided, allowing the user to select which error
conditions are reported. Each bit of the ERROR_MASK register corresponds to a unique
error type.
Separate SD_AUDIO_ERROR_MASK and HD_AUDIO_ERROR_MASK registers for SD
and HD audio cores are also provided, allowing select error conditions to be reported.
Each bit of each ERROR_MASK register corresponds to a unique error type.
By default (at power up or after system reset), all bits of the ERROR_MASK registers are
zero, enabling all errors to be reported. Individual error detection may be disabled by
setting the corresponding bit HIGH in the mask registers.
Error conditions are indicated by a VIDEO _ERROR signal and an AUDIO_ERROR signal,
which are available for output on the multifunction I/O output pins. The two signals are
also combined into a summary DATA_ERROR signal, which is also available on the
multifunction I/O pins. These signals are normally HIGH, but are set LOW by the device
when an error condition has been detected.
These signals are a logical 'NOR' of the appropriate error status flags stored in the
ERROR_STAT_X register, which are gated by the bit settings in the ERROR_MASK
registers. When an error status bit is HIGH and the corresponding error mask bit is LOW,
the corresponding DATA_ERROR signal is set LOW by the device.
The ERROR_STAT_X registers, and correspondingly the DATA_ERROR, VIDEO_ERROR,
and AUDIO_ERROR signals, are cleared at the start of the next video field or when read
via the host interface, which ever condition occurs first. Note that any AUDIO_ERROR
condition will cause DATA_ERROR to assert. Use the SD_AUDIO_ERROR_MASK and
HD_AUDIO_ERROR_MASK registers if masking these events is desired.
All bits of the ERROR_STAT_X registers are also cleared under any of the following
conditions:
1. LOCKED signal = LOW.
2. SMPTE_BYPASS = LOW.
3. When a change in video standard has been detected.
GS2971 3Gb/s, HD, SD SDI Receiver
Data Sheet
45898 - 2
September 2012
64 of 148