Linux: Optical fiber communications, DP83822

user5769257

Other Parts Discussed in Thread: DP83822IF

Tool/software: Linux

Excuse me, I used the Ethernet PHY chip DP83822 for fiber communication, but I encountered a problem: the Rx port of the optical fiber sending end needs to detect the signal before starting to send data.What I need, however, is one-way communication. How can I solve this problem?Thank you very much!(sorry for the poor English)

over 6 years ago

0 Rob Rodrigues over 6 years ago

TI__Mastermind 19780 points

Hi Lingfu,

Usually detecting signal before sending data is a function of the fiber transceiver.

For example, look at the "loss of signal" pin in this SFP module: www.broadcom.com/.../hfbr-57e0apz

This is an inverted signal on what you need, and how the task of detecting signal is usually handled.

Best Regards,

0 user5769257 over 6 years ago in reply to Rob Rodrigues

Intellectual 420 points

Dear Mr. Rob Rodrigues,

First of all, thank you very much for your help. Then I would like to ask you another question. My design is as follows:

After my test, when the Rx terminal is grounded, the Tx terminal will send the data, and then I want to directly connect the Rx terminal to GND when the circuit is designed. Could you please help me see if this design is feasible?

Thank you very much

lingfu Li

0 Rob Rodrigues over 6 years ago in reply to user5769257

TI__Mastermind 19780 points

hi lingfu,

It is not a good idea to tie the RX pins directly to ground. A 50 ohm impedance should be used to reduce emissions.

Best Regards,

0 user5769257 over 6 years ago in reply to Rob Rodrigues

Intellectual 420 points

Thank you very much

0 user5769257 over 6 years ago in reply to Rob Rodrigues

Intellectual 420 points

Hi Rob Rodrigues,
I have another problem, I need your help. The DP83822IF I mentioned before does the design of optical fiber communication, connecting the Rx port with 50 ohms resistance
To GND, after my test, Tx port data cannot be sent out.What is needed is a low level signal to the Rx port before sending the data again.Also,
Would it not be a problem to connect Rx to Tx (since the device sending the data is doing one-way communication, ignoring the data received)?
Best regards,
Lingfu Li

0 Rob Rodrigues over 6 years ago in reply to user5769257

TI__Mastermind 19780 points

Hi lingfu,

Can you please start a new help thread since this is outside of your original question?

Best Regards,

Interface

Interface forum

Linux: Optical fiber communications, DP83822