DS90UB901Q Datasheet, PDF (33/45 Pages) Texas Instruments – 10 - 43MHz 14 Bit Color FPD-Link III Serializer and Deserializer with Bidirectional Control Channel

FIGURE 29. I²C Pass Through
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SYNCHRONIZING MULTIPLE CAMERAS
For applications requiring multiple cameras for frame-syn-
chronization, it is recommended to utilize the General Pur-
pose 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 birec-
tional 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 specifi-
cations.
For example in the configuration shown in (Figure 30):
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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