DP83822I: SERCOS-3 support

Lutz Naumann

Part Number: DP83822I

Dear Team

can DP83822 be used for SERCOS-3? Unfortunately the datasheet does not clarify the timing for Link Loss Detection and False Carrier Detection and its signaling.SERCO-3 requires the following timings and we would like to understand, if the PHY can fulfill this or not:

- Link losses shall be detected with "False carrier" or link loss detection

Output of "False Carrier" signal on the MII interface (RxER and error code E on RxD). The detection of "False Carrier" shall be less then 20µs. "False Carrier" detection shall be signaled for at least 20 µs.

link loss detection (output of LED) shall be less then 20µs.

- The link signalization shall be level based.

many thanks

Lutz

over 7 years ago

0 Ross Pimentel over 7 years ago

TI__Mastermind 23675 points

Hi Lutz,

The DP83822I supports the features.
Please see section 8.4.11 in the datasheet.

0 Lutz Naumann over 7 years ago in reply to Ross Pimentel

TI__Expert 6590 points

Thanks Ross,

I found that section before but do have some difficulties extracting the answers to the above requirements. A link loss or a false carrier shall be detected within 20us. In or data sheet we are describing that we can drop the link in 10us. Does this include the above mentioned detection? The question is about the timings of link loss and false carrier detection not about how fast we can drop the link. Also for the LED question.

thanks
Lutz

0 Lutz Naumann over 7 years ago in reply to Lutz Naumann

TI__Expert 6590 points

Hello Ross,

I had another discussion and it also seems to be unclear from the datasheet if the output "false carrier" signal will be available on the MII interface (RxER and error code E on RxD)? Can please look into this as well?

many thanks

Lutz

0 Lutz Naumann over 7 years ago in reply to Lutz Naumann

TI__Expert 6590 points

Hi Team,

any feedback on the above questions?

Lutz

0 Ross Pimentel over 7 years ago in reply to Lutz Naumann

TI__Mastermind 23675 points

Hi Lutz,

It takes tens of nanoseconds for the data to traverse the PHY.
Because of that, the PHY will detect and drop the link within 10uS of seeing those errors.

When a false carrier is detected, the RX pins will transition to indicate this as you have outlined above.
RX_ER = 1
RXD = 0xE

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DP83822I: SERCOS-3 support