DP83620-EVK: DP83620-EVK: SFP Transceiver compatibility

Thibaut Dewet

Prodigy 10 points

Part Number: DP83620-EVK
Other Parts Discussed in Thread: DP83620, TIDA-00928

Hello,

I'm working on DP83620-EVK with a 1000BASE-SX SFP Transceiver. But no traffic is observed.

The phy is configured in fiber mode (i.e: FX_EN):

If I set the loopback (MII) the packets are sent and received correctly (so the phy configuration seems correct).
If I create a loopback with the fiber, nothing is received.

I'm not sure about the compatibility between the phy and the transceiver.

Can a 100BASE-FX phy work with a 1000BASE-SX Transceiver or do the phy and tranceiver base have to match ?

Registers values:

[0x00]       0x2100
[0x01]       0x78c9
[0x02]       0x2000
[0x03]       0x101
[0x04]       0x0
[0x05]       0x4
[0x06]       0x3
[0x07]       0x0
[0x08]       0x14b
[0x09]       0x1
[0x0A]       0x21
[0x0B]       0x2
[0x0C]       0x0
[0x0D]       0x0
[0x0E]       0x0
[0x0F]       0x0
[0x10]       0x0
[0x11]       0x0
[0x12]       0x0
[0x13]       0x0
[0x14]       0x0
[0x15]       0x0
[0x16]       0x0
[0x17]       0x0
[0x18]       0x0
[0x19]       0x0
[0x1A]       0x0
[0x1B]       0x0
[0x1C]       0x0
[0x1D]       0x0
[0x1E]       0x0
[0x1F]       0x0

Best regards

Thibaut

over 3 years ago

0 Nikhil Menon over 3 years ago

TI__Genius 11725 points

Hi Thibaut,

We are looking into your question and will have additional feedback by early next week.

Thank you,

Nikhil

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and it is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

0 Nikhil Menon over 3 years ago in reply to Nikhil Menon

TI__Genius 11725 points

Hi Thibaut,

Apologies for the delay. I believe it is up to the transceiver, whether or not it can support a specific standard. Please refer to the Transceiver datasheet for this.

Thank you,

Nikhil

0 Thibaut Dewet over 3 years ago in reply to Nikhil Menon

Prodigy 10 points

Hello Nikhil,

Thank you for your answer.

I change the SFP , Now I use a 100BFXST which should be compatible. Unfortunatly it doesn't. I observed that the LINK LED is never up.

I tried to use the BIST to validate the data path. A loop is done by the fiber, and I set the BIST_START bit in PHYCR but the PHYCR the BIST_START value is always 0, it means no receive traffic has been detected. I checked the TD+ TD- signals but no traffic is generated.

Next I set the UNIDIRECTIONAL ENABLE bit BMCR. Now I see the traffic on TD+/- and RD+/- but BIST_START value is still 0.
I don't understand why the receive BIST engine does not detect packet traffic. Do you have any idea ?

Another question about the recommended circuit for a 100 Mb/s fiber pair interface in the DP83620 datasheet. As the SFP with msa standard already have AC coupling capacitors on TD lines, is it ok to remove the capacitors and resistors on the eval board ?
I did it but the signal amplitude is very different between TX and RX. Is it normal ?

TX:

yellow: TD+
blue: TD-
red: diff TD+ TD6

RX:

yellow: RD+
blue: RD-
red: diff RD+ RD-

Best regards,

Thibaut

0 Kallikuppa Sreenivasa over 3 years ago in reply to Thibaut Dewet

TI__Guru**** 152319 points

Hello Thibaut

We have done the fiber interface and tested on TIDA-00928 and TIDA-0049. Please check if this helps.

Regards,

Sreenivasa

0 Thibaut Dewet over 3 years ago in reply to Kallikuppa Sreenivasa

Prodigy 10 points

Hello Sreenivasa,

Thanks for your answer.

After several tests, it works. There were two problems:

- The Signal Detect level was reversed. It is a Signal Detect on DP83620 but a Signal Loss from the SFP transceiver.

After the correction we were able to send traffic but not able to receive.

- The RD+/- signal level were to high. We returned to the recommended circuit for a 100 Mb/s fiber pair interface
(i.e Figure 9-2) and we add a 100 Ω resitor between RD+ and RD- , as it is mentioned in MSA documentation.

After that we were able to receive traffic.

Best regards,

Thibaut

0 Kallikuppa Sreenivasa over 3 years ago in reply to Thibaut Dewet

TI__Guru**** 152319 points

Hello Thibaut

Good to hear the communication is working.

Did you use an SFP module ? Is there a part number you could share.

I assume you interfaced the device to a host using MII interface based on your loopback tests ?

Regards,

Sreenivasa

0 Kallikuppa Sreenivasa over 3 years ago in reply to Kallikuppa Sreenivasa

TI__Guru**** 152319 points

Hello Thibaut

Do you have some update for me.

Regards,

Sreenivasa

0 Thibaut Dewet over 3 years ago in reply to Kallikuppa Sreenivasa

Prodigy 10 points

Hello Sreenivasa

Sorry for my late answer.

We use an SFP100BFXST you can find the description on https://www.startech.com/en-us/networking-io/sfp100bfxst.

You're right the DP83620 is interfaced with an STM32 using MII interface.

Best regards,

Thibaut

+1 Kallikuppa Sreenivasa over 3 years ago in reply to Thibaut Dewet

TI__Guru**** 152319 points

Hello Thibaut,

Thank you for your inputs. If you do not have additional questions i will close the thread.

If possible, please press the resolved button.

Regards,

Sreenivasa

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DP83620-EVK: DP83620-EVK: SFP Transceiver compatibility