DS90UB901Q_15 Datasheet, PDF (31/50 Pages) Texas Instruments – 10 - 43MHz 14 Bit Color FPD-Link III Serializer and Deserializer with Bidirectional Control Channel

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DS90UB901Q, DS90UB902Q
SNLS322E – JUNE 2010 – REVISED APRIL 2013
Figure 31. I²C Pass Through
SYNCHRONIZING MULTIPLE CAMERAS
For applications requiring multiple cameras for frame-synchronization, it is recommended to utilize the General
Purpose Input/Output (GPIO) pins to transmit control signals to synchronize multiple cameras together. To
synchronize the cameras properly, the system controller needs to provide a field sync output (such as a vertical
or frame sync signal) and the cameras must be set to accept an auxiliary sync input. The vertical synchronize
signal corresponds to the start and end of a frame and the start and end of a field. Note this form of
synchronization timing relationship has a non-deterministic latency. After the control data is reconstructed from
the birectional control channel, there will be a time variation of the GPIO signals arriving at the different target
devices (between the parallel links). The maximum latency delta (t1) of the GPIO data transmitted across
multiple links is 25 us.
Note: The user must verify that the timing variations between the different links are within their system and timing
specifications.
For example in the configuration shown in (Figure 32):
The maximum time (t1) between the rising edge of GPIO (i.e. sync signal) arriving at Camera A and Camera B is
25 us.
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