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TDA4VM-Q1: Ethernet for custom TDA4VM board.

Gautham Angadi
Intellectual 280 points

Part Number: TDA4VM-Q1
Other Parts Discussed in Thread: TDA4VM

Hi TI Team,

I am developing a custom PCB based on the TDA4VM with a board diameter of 65 mm. The PCB is intended for video data logging from an imager over Ethernet. The imager outputs grayscale video at a resolution of 1280 × 720 and 60 FPS, resulting in an approximate bandwidth requirement of 421 Mbps.

In addition to video logging, we require Ethernet connectivity for TCP-based command communication and remote shell operations such as SSH and SCP for transferring logged data from the system.

Due to PCB space constraints, we would like to know whether a single Ethernet port can be used for both purposes by logically sharing the available bandwidth (for example, allocating approximately 600 Mbps for video logging and 400 Mbps for command, SSH and SCP traffic).

If this configuration is supported, could you please share the recommended architecture, implementation approach and any relevant schematics or reference designs?

The above architecture will be implemented in ARM Linux cortex of TDA4VM.

Thank you for your support.

  • 0
    TI__Mastermind 43830 points

    Hi,

    I am assuming that you will be using the standard linux and all the data sources and sinks for ethernet will be in the same OS. In that case, you can do this split. There are different ways to do this based how rigorous you want the data separation and rate limiting to be. But by default it is not an issue to send both the data streams from the same interface. You can put rate limiting on the ssh and scp traffic and let the video stream take the rest of the bandwidth. This is because I am assuming that the video data is realtime and won't be hogging the entire bandwidth anytime.

    Are you looking for any hardware based limiting options? Otherwise, you can consider traffic shaping using the tc command on linux. Something like this should be enough for you correct.

    Regards,
    Tanmay

  • 0 in reply to Tanmay Patil
    Intellectual 280 points

    Hi Tanmay,

    The below is my system configuration

    • Camera → TDA4VM
      • The imager outputs grayscale video over an 8-wire subset of a 25-pin connector (which carries Ethernet signals).
      • TDA4VM collects this video data via that 25-pin connector.
    • TDA4VM → Outside Host
      • There’s a separate Ethernet female socket on the PCB for connecting to an external system (PC, server, etc.).
      • This connection is used for SSH, SCP, TCP commands, basically system management and data transfer.
  • 0 in reply to Gautham Angadi
    TI__Mastermind 43830 points

    Hi Gautham,

    Essentially this means that there are two different physical connections for the two data paths. Hence on hardware side, you should not have any issues with bandwidth sd esch port is capable of gigabit ethernet.

    Regards,
    Tanmay

  • 0 in reply to Tanmay Patil
    Intellectual 280 points

    Hi Tanmay,

    I have a question regarding the Ethernet architecture for our custom TDA4VM board.

    Our application requires two Ethernet-based functionalities in software, but due to PCB size constraints I'm trying to keep the board as compact as possible and would prefer to have only one physical Ethernet connector.

    From a hardware perspective, how would you recommend designing the PCB for this scenario?

    Specifically:

    • Is it possible to support two Ethernet applications while exposing only a single external Ethernet port?
    • Can this be achieved using the TDA4VM's Ethernet subsystem alone, or would it require an external Ethernet switch or any additional hardware?
    • Under what conditions would two independent PHYs/RJ45 connectors become mandatory?
    • Are there any TI reference designs or recommended architectures for this type of implementation?

    I'm trying to understand the most practical hardware architecture before finalizing the PCB, as minimizing board area is an important design goal.

    Thanks!

  • 0 in reply to Gautham Angadi
    TI__Mastermind 43830 points

    Hi Gautham,

    Gautham Angadi said:
    Our application requires two Ethernet-based functionalities in software, but due to PCB size constraints I'm trying to keep the board as compact as possible and would prefer to have only one physical Ethernet connector.

    But on the board the sources would come on different interfaces I beleive right. Are you then planning on combining both the sources on the PCB. If not what is the plan to combine them on hardware side to be fed into a single ethernet connector?

    Sorry I am not able to understand the hardware picture here. Can you perhaps share some block diagram for this?

    Regards,
    Tanmay

  • 0 in reply to Tanmay Patil
    Intellectual 280 points

    block diagram

    1G Ethernet Network

    +-------------+                   +-----------------+               +--------------+
    | Ground     |                  | Ethernet Switch |            |  Imager    |
    | Station      |<----------->|                           |<------>| (Camera) |
    +-------------+                   +--------+-----------+          +--------------+
                                                       |
                                                       |
                                                       |
                                            +------▼-------+
                                             |   TDA4VM   |
                                             +---------------+

    We want to implement this connection on our custom PCB. kindly provide the references for implementing above block diagram.

  • 0 in reply to Gautham Angadi
    TI__Mastermind 43830 points

    Hi,

    So you have an external switch right. In that case from TDA4 perspective, it will only be a single connection over any ethernet connector. What mode is the ethernet switch interface?

    Is there any ethernet phy you are using? Or is the connection between EThernet switch and TDA4VM supposed to be MAC to MAC?

    Regards,
    Tanmay

  • 0 in reply to Tanmay Patil
    Intellectual 280 points

    Hi  

    We are using Microchip KSZ9563R ethernet switch it has RGMII for tda4vm and inbuilt phys for ground station and imager. Kindly confirm us our understanding.


    Having switch in between what are the OS level changes expected such as pinging imager or receiving data from imager to tda4vm and sending commands from gs to tda4vm or SCP.

  • 0 in reply to Gautham Angadi
    TI__Mastermind 43830 points

    Hi Gautham,

    Gautham Angadi said:
    Having switch in between what are the OS level changes expected such as pinging imager or receiving data from imager to tda4vm and sending commands from gs to tda4vm or SCP.

    The OS would expect either the switch to be bootstrapped or there to be a switch driver to be present. The switch driver would come from switch manufacturer. Microchip typically has the driver upstreamed so it should be also present in our SDK. You can confirm this with microchip.

    Apart from that, as I have said earlier, it should not be a problem while sending both the traffic on the gigabit link.

    Regards,
    Tanmay