DS90UB960-Q1: hot-plug issue when using interleave mode

Hello,

Can I ask what is the reason to remove a camera?  Are you just simply disconnecting the 935 from the 960?  For line-interleaving to work all the video data needs to be synchronized.  If cameras gets out of sync like if one is removed, then it is not going to work properly.  You can get line-interleaving to work with three cameras instead of four but you will have to make sure that they are synchronized.  If you want the image data from one camera to not be used can you use the SoC instead?

Are you able to provide just a bit more background here?  I want to fully understand what you are trying to accomplish.

Regards,

Nick

Hi Nick,

Thanks for your feedback. 935 is in the camera side, and they will just unplug the camera.

There are two reasons to remove the camera. One is they are simulating the fault scene, when the system is running normally, there may be a scene where one or two camera is poorly contacted or dropped. The second is that they want to achieve hot-plug function. The CAR OEM's requirement is When one camera is accidentally dropped, the other three can work normally.

Thanks & Best Regards,

Sherry

Hello Sherry,

So for line interleaving mode, I don't believe this is going to be possible since it is going to desynchronize the cameras.  Additionally only one FS and FE packet will be forwarded instead of four, this could cause additional issues if these packets are originating from the lost camera.  How many VCs will you have access to?  Is it possible to reprogram to RR if Lock is lost for one imager or resynchronize the remaining cameras?

Regards,

Nick

Hi Darash,

Thanks for your reply! They can only use one VC channel, so it is not feasible for the customer to change to RR mode when one camera lost. If one camera lost, our 960 detect desynchronization for the four cameras, and then 960 will drop other three cameras data and wait for next line, right?

Thanks & Best Regards,

Sherry

Hello Sherry,

You are correct however it is never actually getting all four data streams back to synchronize.  So its waiting a certain amount of time for data to be available in all for buffers and then interleaving and forwarding as one large frame.  If data is missing then it is not synced.  It does try to resync at the start of the next frame but it can't.  

So I think it would be necessary to resync the remaining working cameras and just forward those.  Is there a period of time after a failure where the system can try to correct?

Regards,

Nick

Hi Darash,

Thanks for your analysis.

Yes, we also want to check whether we have any solution to resync the remaining working cameras and just forward those. Can we achieve this function through 960's register configuration? 

1. Firstly, I want to conform that if one camera drops and the display has no image, the root cause is 960's interleave mode, not SOC's software issue, right? Because in the interleave mode, 4 cameras data must be sync, once one camera is lost, sync failed, 960 will have no output, then the display is black. So 960 interleave mode is the root cause, Right?

2. Secondly, if the root cause is 960's interleave mode, one camera is lost, the display is black. Then we connect this camera again, 960 can output normally and does not need to be re-powered, right?

3. In our datasheet, there is a description as below. How does our chip know the sync failed? If one camera drops, then I disable this channel's forwarding, then I can resync the remaining working cameras and just forward those, right? Is there any other way to resync the remaining working cameras?

4. If one camera drops, we detect the lock is low, can our device generate the video data to replace the dropped camera data?

Thanks & Best Regards,

Sherry

Hi Nick,

Clear! Thanks for your detailed explanation！

Thanks & Best Regards,

Sherry