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TS5MP645: Issue with switching the port

Malik Bathusha
Prodigy 20 points
Part Number: TS5MP645
Other Parts Discussed in Thread: TMUX646

Tool/software:

Hi,

We use TS5MP645NYFPR in our design to connect 2x4lane cameras with the processor(attached switch schematics section below). Camera-A  is connected to an A port of the MIPI switch and streaming without any issues. If I switch to camera B using the switch SEL pin, Camera-B is not streaming 

My question is,

1.  what is the sequence to switch the camera? Can I directly switch the camera using the SEL pin while nOE is enabled? or nOE needs to disabled, switch the camera using the SEL pin, then enable nOE.

Thanks, 

- Malik

  • 0
    TI__Mastermind 24440 points

    Hi Malik,

    Your first interpretation of the control logic is correct.( The select pin can be toggled while the enable is always held low) This should allow you to switch from Camera A to Camera B without issues so that should not be the problem here.

    We could start by us discussing what is the frequency or data rate of the signals being passed to Camera B through the TS5MP645?

    This device has a bandwidth of 1.5Ghz and if the frequency of the signal being passed through it is  close to that bandwidth you could see significant signal distortion and system problems.

    In addition I did find another older post that talked about somebody doing application that is similar to yours but the camera interface for their cameras where different. Do the cameras in your application have different interfaces?

    Ultimately there is a device called the TMUX646 that is a p2p upgrade of the TS5MP645 but has a higher bandwidth of 6GHz which allows for higher data rate signals to be put through this device.

    Please let me know what you think here and we can continue to dig into what the problem could be here.

    Regards,

    Kameron

  • 0 in reply to Kameron Hill
    Prodigy 20 points

    Hi Kameron,

    Thanks for the response.

    To answer your questions, 

    1. Camera A and Camera B are the same sensors. Camera output data rate, resolution, and every other camera settings are the same for both the camera. Since Camera A is working fine, I hope Bandwidth is not the issue.

    2. Both the cameras have the MIPI interface. 

    3. I will check the availability of TMUX646 and test with the same.

     I have another update to share here,

    If I connect the SEL pin to pull-up by default, Camera B will be streaming fine.  Earlier, it was connected to pull-down and camera A is streaming fine.

    So, I suspect that the switching might be the problem. 

  • 0 in reply to Malik Bathusha
    TI__Mastermind 24440 points

    Hi Malik,

    Thanks for this extra info.

    The TS5MP645 has internal 6Mohm weak pull down resistors on the control pins.

    The strong pull up resistor of 4.7K ohms connected to 1.8V makes sense to me and I understand that should send a logic high to the device and connect Camera B.

    So if we had not external pull up or pull down resistor on the line then the internal pulldown of the device would takeover and Camera A would be connected.(The line would see logic low)

    In this same scenario if you the connected your select pin to a driver that sent a logic HIGH signal, then Camera B would be connected.

    Malik Bathusha said:
    If I switch to camera B using the switch SEL pin, Camera-B is not streaming 

    Can you check the select pin driver in your design?( What is the output high voltage it is sending)

    It needs to send 1.425V to register a high for this device.

    Please let me know what you think and if I am missing something.

    Regards,

    Kameron