DS90UB954-Q1: Using two cameras with different resolutions and frame rates, replication?

Julio Apps

Part Number: DS90UB954-Q1

Hi Team,

I have a 2 camera application that uses the DS90UB954-Q1, its a 1.7M and 1M cameras that will work simultaneously and will need to replicate and forward this data like shown in figure 53 of the datasheet. I want to verify my thoughts to see if this is a possible applications.

The BW requirements from the cameras will be the following. From the bandwidth perspective it looks possible to aggregate the camera inputs on 2 lanes and use the other 2 lanes to replicate each camera input. Is this correct?

12bits x 1.7M x 36FPS x 1.3Overhead =~ 954 Mbps

10bitx 1M x 36 FPS x 1.3 Overhead =~468Mbps

I saw the following post and i beleive it confirms my thoughts above but want to verify i am not missing anything.

https://e2e.ti.com/support/interface/f/138/t/805084

over 5 years ago

0 Casey McCrea over 5 years ago

TI__Guru** 103215 points

Hello Julio,

Yes, in this configuration the 954 should have plenty of bandwidth to support the above configuration.

Best Regards,
Casey

0 Julio Apps over 5 years ago in reply to Casey McCrea

TI__Expert 3665 points

Casey,

Thanks for confirming. Also, just a theoretical question. I found that the first camera is actually 20bits not 12 so the BW requirement will be around 1.6Gbps. Which is still within the limits on one Mipi lane of the device. Buts lets say it required higher bandwidth than 1.6Gbps is the data able to send over 2 lanes or it does not work that way?

0 Casey McCrea over 5 years ago in reply to Julio Apps

TI__Guru** 103215 points

Hello Julio,

In 2x2 lane configuration each 2 lane port can support up to 3.2Gbps total bandwidth (2x1.6Gbps)

Best Regards,

Casey

0 Julio Apps over 5 years ago in reply to Casey McCrea

TI__Expert 3665 points

Hi Casey,

Last clarifying question. Now that i have 2x 20 bit cameras how do i verify the this will be ok on the forward channel? I need 1.6Gbps for 1 camera and 1Gbps for the other camera. Will the FC need to operate at 2.6Gbps for this to work? i see that the max REFCLK is 26MHz so the FC can operate up to 26MHzx 12bits = 3.12Gbps. That means the FC has more than enough BW correct?

0 Casey McCrea over 5 years ago in reply to Julio Apps

TI__Guru** 103215 points

Julio,

If you are using 953/935 serializers then the forward channel always operates at fixed frequency. For REFCLK = 25MHz, then the forward channel is 25*160 = 4Gbps and the max allowable CSI-2 bandwidth is 25*128 = 3.2Gbps.

Best Regards,

Casey

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DS90UB954-Q1: Using two cameras with different resolutions and frame rates, replication?