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DP83848I: Connection issue while network storm occurred...

Peter Tseng
Mastermind 6150 points
Part Number: DP83848I

Dear Sirs,

My customer needs comments on DP83848I design. Their device is power monitor/meter of AC power.

1. when the network storm occurs, device LINK & ACT LEDs are turned off.

2. After device reboot, connect it to PC, the PHY still not work, LINK & ACT LEDs still off.

3. check the register: reg<0x0001> Bit 2 Link Status is "0"

Customer add a debug code to check if the link status is "0" and keep 10 mins, the device will be reboot.

This can fix the problem above but will have another issue:

1. Customer cannot know the link status is "0" caused by real network disconnect or due to PHY hang on.

2. with this debug code, the device will always reboot in the field test if the LAN cable did not attach.

  

May I have your help if there is any better solution or suggestion for customer?

Thanks.

  • 0
    TI__Intellectual 2260 points

    Peter,

    I am confused by what you mean by "network storm." What is this? Also, does that mean the PHY is linked before the "network storm?"

    Furthermore, what is causing LEDs to go away? Is the device powered off/disconnected?

    Lastly, what operating temperatures are these tests being conducted under?

    Sincerely,

    Jason Lee

  • 0 in reply to James Lee
    Mastermind 6150 points

    Hi Sir,

    The network storm is just known as the broadcast storm.

    You can refer to the below link.

    https://forumautomation.com/t/what-is-network-storm/10699

    Before the storm, PHY works fine.

    While the LED was turned off, the system still powered on.

    The system work temp is normal(30 degree C). 

  • 0 in reply to Peter Tseng
    TI__Intellectual 2260 points

    Peter,

    Thank you for sending this informative link. Now knowing the definition of network/broadcast storm, I suspect the processor or MAC may be the issue here. 

    Sincerely,
    Jason Lee

  • 0 in reply to James Lee
    Mastermind 6150 points

    Hi Jason,

    Thanks for your reply!

    Is there any suggestion to help customer questions after they added the debug code?

    Thanks.

    =============

    1. Customer cannot know if the link status is "0" caused by a real network disconnect or due to PHY hanging on.

    2. with this debug code, the device will always reboot in the field test if the LAN cable did not attach

    =============

  • 0 in reply to Peter Tseng
    TI__Intellectual 2260 points

    Peter,

    Can you give me more details regarding how this debug code works? Also, has the customer managed to check processor or MAC for any potential issues?

    Sincerely,

    Jason Lee

  • 0 in reply to James Lee
    Mastermind 6150 points

    Hi Jsson,

    Let me explain more!

    Once the network storm occurs, the network disconnected and LEDs will be turned off.

    At this moment, customer thinks the MCU and MAC(embedded in MCU) are still workable since they can read the PHY register data (Link status) from MAC to PHY, and get the link status is "0" which means the connection is lost.

    Re-plug the LAN cable can't fix it and the LEDs are still off.

    What customer can see is the connection loss but they can't identify if it is caused by PHY hang up or actual network lost.

    Is there any register of DP83848I for customer checking or reading to know if PHY is still alive or not?

    Thanks.

  • 0 in reply to Peter Tseng
    TI__Intellectual 2260 points

    Peter,

    LED_LINK, LED_SPEED have inverted polarity on DP83848 by default (i.e., high voltage for off and low voltage for on). The reason behind this is explained in section 6.3.3.1 of the datasheet. Could you check that these are setup correctly?

    Furthermore, please check that all of the bootstrap settings are correctly configured for the mode you are targeting.

    Also, as you mentioned before, the PHY will indicate that it has established link with a link partner over the LED_LINK pin (ON = link established). Register reg<0x0001> Bit 2 will also provide the link status of the PHY.

    Sincerely,

    Jason Lee