DP83848K: DP83848K: question

So there is no absolute relationship between our current pin loss and this register becoming High?

Hi Joe,

This is correct. However if you are having link down issues, this would give us a hint as to what the root cause is. What is current problem that you are facing? Are we losing link unexpectedly? Could you provide more information?

Regards,

Alvaro

We are currently experiencing a sudden disconnection when using the DP83848K PHY for a period of time, but sometimes it is always normal. Currently, it is found that the disconnection is caused by an error received by the DP83848K PHY. Is there any debug message for the DP83848K PHY to assist in further analysis?

Hi Joe,

Questions:

1. Will the DP83848 regain link after a power cycle or by unplugging and reconnecting the ethernet cable?
2. Does this happen when we use a different cable or different link partners?
3. What is the current test procedure?
4. How long is the link stable before dropping link?
5. What speed if the PHY linking up at?

For further debug, read all registers during a working case, then during non-working and see what changed. Is this what you already did and "False Carrier Sense" was the only register that changed?

Regards,

Alvaro

Hi Alvaro：

       Reply is as follows

1. Will the DP83848 regain link after a power cycle or by unplugging and reconnecting the ethernet cable?

          Ans：The connection will be automatically restored without restarting, and sometimes the disconnection problem will not occur after the connection is                        restored. The disconnection problem occurs randomly.

        2.Does this happen when we use a different cable or different link partners?

           Ans：I have replaced peripheral equipment and cables, but the problem still exists.

        3.What is the current test procedure?

          Ans：Our machine operates at low temperatures of -40 degrees Celsius

        4.How long is the link stable before dropping link?

          Ans：Restores the connection in about 30 seconds after being disconnected

       5.What speed if the PHY linking up at?

           Ans：The connection is made at a speed of 100M

For further debug, read all registers during a working case, then during non-working and see what changed. Is this what you already did and "False Carrier Sense" was the only register that changed?

          Ans：When a network disconnection occurs, the Debug message displayed on the SOC indicates that the PHY is disconnected, and the "False                            Carrier Sense" register will definitely become High. However, if "False Carrier Sense" becomes High, the disconnection may not occur.

Currently, judging from the SOC message, I don't know why the PHY and SOC lost connection when the network was disconnected.

Thanks

Joeyan

Hi Alvaro：

      For normal and failed connections, we have captured the DP83848 register value as shown in the figure below. What is the reason for this exception 0x01h?

Hi Joe,

joe.yan said:

Our machine operates at low temperatures of -40 degrees Celsius

Thank you for mentioning this. Is it possible to run this test at room temperate (25C)? I want to rule out the possibility of this being temperature dependent.

As for Reg 0x1, this change is to be expected. It tells us that the link is down, auto-negotiation is a mechanism used to establish link, so if link goes down then then auto-neg status is also expected to go down.

Reg 0x14 in your Link Fail log shows the maximum amount of RX Errors, this could be the reason of the link down. Is the link partner also at -40C?

Regards,

Alvaro

Hi Alvaro：

      1、Thank you for mentioning this. Is it possible to run this test at room temperate (25C)? I want to rule out the possibility of this being temperature                          dependent.

            Ans： Our Camera works at -40 degrees, but the IC works at around 10 degrees (there is a heater inside the camera)

      2、As for Reg 0x1, this change is to be expected. It tells us that the link is down, auto-negotiation is a mechanism used to establish link, so if link goes                 down then then auto-neg status is also expected to go down.

           Ans：We can judge from this that the SOC and PHY are connected normally, but is there a problem with the connection between the PHY and the                             external Hub?

      3、Reg 0x14 in your Link Fail log shows the maximum amount of RX Errors, this could be the reason of the link down. Is the link partner also at -40C?

           Ans：Except for our machine, which is in the chamber at -40 degrees, the rest of our equipment is in an outdoor environment of 25 degrees.

Thanks

Joeyan

Hi Joeyan,

Did you try the test setup with the board outside of the -40 degree chamber? Do we still see the same issues?

Regards,

Alvaro

Because the problem occurs randomly, sometimes the problem persists at a low temperature of -40°C, 
and sometimes it has not been disconnected for four days. 
In addition, the temporary register information I provided last time can be judged to be that the SOC and PHY are normal. 
Is there a problem with the external Hub section of the PHY? Are there other registers that can help with further judgment?

Hi Joe,

This is difficult for me to debug. The False carrier sense latch message could be a hint about the connector side signal getting corrupted. Is the transformer and all other components on your board rated for -40C too? Again I would try to reproduce this at room temperature and in many different ways to try to consistently recreate this issue. 

When the link goes down, you mentioned that sometimes the link will come back on it's own, without the need to power-cycle, unplug the cable, or restart auto-negotiation. How long is the link down when this issue arises?

Regards,

Alvaro

The disconnection time is very random, sometimes it lasts for 30 seconds, and sometimes it keeps disconnecting and reconnecting
 repeatedly, but in the end it will automatically restore the connection. Is there a way for DP83848K to further confirm?

Hi Joe,

Could we try different cable lengths? I can try to recreate this issue in lab (at room temperature) and get back to you next week.

Regards,

Alvaro