DS90UB964-Q1 Datasheet, PDF (33/116 Pages) Texas Instruments – DS90UB964-Q1 Quad FPD-Link III Deserializer Hub

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DS90UB964-Q1
SNLS500 – JULY 2016
WriteI2C(0x19,0x00) # FS_HIGH_TIME_1
WriteI2C(0x1A,0x8A) # FS_HIGH_TIME_0
WriteI2C(0x1B,0x04) # FS_LOW_TIME_1
WriteI2C(0x1C,0xE1) # FS_LOW_TIME_0
WriteI2C(0x18,0x01) # Enable FrameSync
8.4.19 CSI-2 Forwarding
Video stream forwarding is handled by the forwarding control in the DS90UB964-Q1 on FWD_CTL1 register
0x20. The forwarding control pulls data from the video buffers for each FPD3 RX port and forwards the data to
one of the CSI-2 output interfaces. It also handles generation of transitions between LP and HS modes as well
as sending of Synchronization frames. The forwarding control monitors each of the video buffers for packet and
data availability.
Forwarding from input ports may be disabled using per-port controls. Each of the forwarding engines may be
configured to pull data from any of the four video buffers, although a buffer may only be assigned to one CSI-2
Transmitter at a time. The two forwarding engines operate independently. Video buffers are assigned to the CSI-
2 Transmitters using the mapping bits in the FWD_CTL1 register 0x20[7:4].
8.4.19.1 Best-Effort Round Robin CSI-2 Forwarding
By default, the round-robin (RR) forwarding of packets use standard CSI-2 method of video stream
determination. No special ordering of CSI-2 packets are specified, effectively relying on the Virtual Channel
Identifier (VC) and Data Type (DT) fields to distinguish video streams. Each image sensor is assigned a VC-ID to
identify the source. Different data types within a virtual channel is also supported in this mode.
The forwarding engine forwards packets as they become available to the forwarding engine. In the case where
multiple packets may be available to transmit, the forwarding engine typically operates in an RR fashion based
on the input port from which the packets are received.
Best-effort CSI-2 RR forwarding has the following characteristics and capabilities:
• Uses Virtual Channel ID to differentiate each video stream
• Separate Frame Synchronization packets for each VC
• No synchronization requirements
This mode of operation allows input RX ports to have different video characteristics and there is no requirement
that the video be synchronized between ports. The attached video processor would be required to properly
decode the various video streams based on the VC and DT fields.
Best-effort forwarding is enabled by setting the CSIx_RR_FWD bits in the FWD_CTL2 register 0x21.
8.4.19.2 Synchronized Forwarding
In cases with multiple input sources, synchronized forwarding offers synchronization of all incoming data stored
within the buffer. If packets arrive within a certain window, the forwarding control may be programmed to attempt
to synchronize the video buffer data. In this mode, it attempts to send each channel synchronization packets in
order (C0, C1, C2, C3) as well as sending packet data in the same order. In the following sections, Camera 0
(C0), Camera 1 (C1), Camera 2 (C2), and Camera 3 (C3) refers to the camera connected at FPD3 RX port 0, RX
port 1, RX port 2, and RX port 3 respectively. The following describe only the 4-port operation, but other possible
port combinations apply.
The forwarding engine for each CSI-2 Transmitter can be configured independently and synchronize up to all
four video sources.
Requirements:
• Video arriving at input ports should be synchronized within approximately 1 video line period
• All enabled ports should have valid, synchronized video
• Each port must have identical video parameters, including number and size of video lines, presence of
synchronization packets, etc.
The forwarding engine attempts to send the video synchronized. If synchronization fails, the CSI-2 transmitter
stops forwarding packets and attempt to restart sending synchronized video at the next FrameStart indication.
Packets are discarded as long as the forwarding engine is unable to send the synchronized video.
Copyright © 2016, Texas Instruments Incorporated
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