AT-ETU-SYNC
16
DDC relocking, sometimes referred to as “clock stretching”, is method for correcting sync issues on the DDC line.
The DDC line (also known as the I
2
C bus) is part of the HDMI interface and is responsible for transmitting EDID and
HDCP information from the sink to the source. The DDC line contains two signal lanes: SDA (data) and SCL (clock).
Most of the time, the timing between these two lanes is correct. However, lengthy cables and/or intermediate
devices between the source and sink, can introduce synchronization problems between these two lanes. This can
result in a variety of issues, such as flashing picture, drop-outs, artifacts, and incorrect resolution.
Placing the AT-ETU-SYNC in-line, between the source and sink, will usually correct these issues. Experimenting with
the position of the AT-ETU-SYNC, within the system - particularly when intermediate devices are installed - may be
necessary to obtain the correct results. If the problem persists, contact an Atlona Technical Support Engineer for
assistance.
NOTE:
Some HDMI devices do not support clock-stretching.
Source Testing
Sink Testing
1.
Power the AT-ETU-SYNC.
2.
Connect an HDMI cable from the source to the
HDMI IN
port on the AT-ETU-SYNC.
3.
Press and release the
TEST
button on the front panel of the AT-ETU-SYNC.
4. The
SOURCE
and
5V
indicators will display the testing results. Note that since a sink device is not present,
the
HPD
and
SINK
indicators are ignored. Refer to the table on the previous page.
1.
Power the AT-ETU-SYNC.
2.
Connect an HDMI cable from the sink to the
HDMI OUT
port on the AT-ETU-SYNC.
3.
Press and release the
TEST
button on the front panel of the AT-ETU-SYNC.
4. The
SINK
and
HPD
indicators will display the testing results. Note that since a source device is not present,
the
5V
and
SOURCE
indicators are ignored. Refer to the table on the previous page.
DDC Reclocking
NOTE:
When the EDID dial is set to EDID mode 0, during a test procedure, the
LEARN
button will
glow blue. If the EDID dial is set to any other mode, then the
LEARN
button will remain “off”. Setting
the EDID mode will not affect the results of the test procedure.
Basic Operation
