[DP83849IF] How to detect link loss/down

Takahiro Ogo

Hi,
I'd like to know how to detect link loss.

1)
I understand that Link status value of BMSR register is set "0" when the ether phy goes link loss/down,.
Is my understanding correct?

2)
I'd like to know the detail operation about link loss/down.
- Under what conditions does the link loss/down is detected?
- How much time does it take to go link loss from the port is disconnected?

#The datasheet says "The criteria for link validity is implementation specific." in LINK STATUS of BMSR register.
Which means, Not ordinarily open to the user?

3)
After link status is set 0, if the port is connected, it automatically starts the Auto-negotiation. (of course, Auto-negotiation=Enable)

Best Regards,
Taka

over 9 years ago

0 Ross Pimentel over 9 years ago

TI__Mastermind 23675 points

Hi Taka,

1. Yes, you are correct.

2. There are a few mechanisms that determine link: RX Errors, MLT3 errors (when in 100BASE-TX), Low signal quality and energy detection. Link loss time for the DP83849 is around 250uS.

3. If link is lost and the device is configured for Auto-Negotiation capabilities, the Auto-Negotiation state machine will re-start and try to re-connect with a Link Partner.

Kind regards,
Ross

0 Takahiro Ogo over 9 years ago in reply to Ross Pimentel

Genius 5940 points

Hi Ross,
Thank you for your kind support. I understood that.

Best Regards,
Taka

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[DP83849IF] How to detect link loss/down