DP83822IF: 100BASE-FX link cannot established automatically

Hello John, 

Thank you for the query.

Can you please confirm if the SD is used ?

Regards,

Sreenivasa

Hello John, 

Please refer below datasheet recommendations.

TI recommends connecting Signal Detect pin from the Optical Transceiver to the LED_1 pin and enable it using SD_EN bootstrap pin in 100BASE-FX mode. The LED_1 pin is not used in design and that, if the electrical link between the fiber module and the DP83822 is broken, disconnected or otherwise disrupted, the link will recover only by initiating a soft reset through MDIO/MDC interface.

Regards,

Sreenivasa

Hi Sreenivasa,

Thank you for reply.

Yes, customer does connect LOS signal from fiber module to LED1 of DP83822, and they also make corresponding configuration in register 0x0465 based on polarity of LOS signal. And the boot strap pin RX_ER is open (MODE 4). And they also send software RESET command through MDIO/MDC, while it cannot re-establish link.

I think SD signal cannot help to re-establish link since actually the signal is not lost, in stead, a wrong IDLE signal is sent by partner. (the frequency of correct IDLE signal is 62.5MHz, 41MHz IDLE signal is observed during wrong condition.)

Thank you!

John

Hello John,

Thank you for the inputs and Understand  that the SD is present during error condition.

 0x001F PHY Reset Control Register (PHYRCR)

Did customer try bit 15 or Bit 14 ?

Can you please ask customer to check reset using bit 15.

Regards,

Sreenivasa

Hello John,

Quick note. If the Bit15 is used, the registers will reset.

Customer will have to write registers as required. 

Regards,

Sreenivasa

Hello John,

Do you have some updates ?

Regards,

Sreenivasa

Hi Sreenivasa,

Thank you for reply.

Yes, the link can be re-established after correct IDLE signal resumed and a RESET command is issued.

However this is not acceptable also. Our device disconnected the link once wrong IDLE packet was received. Such their system cannot know when the correct IDLE packet resumed and when should their system send RESET command to PHY device. They requires the PHY device can automatically re-establish the link once the link partner resumes to send correct packet. Engineer told me the PHY devices from other competitors do not have such problem at all. Other competitor's PHY device can keep the link even receiving wrong packet, it seems those PHY device just dropped the wrong packet and keep the link connected, while our device disconnected the link and locked in this condition until it is reset. I am wondering is there any configuration register can configure our device into similar working mode? What is the processing mechanism for our device to handle wrong IDLE packet?

Regards,

John

Hello John, 

Thank you for the reply and updates on testing.

Based on the below inputs

They requires the PHY device can automatically re-establish the link once the link partner resumes to send correct packet.

I am wondering is there any configuration register can configure our device into similar working mode? 

are you checking if there are some register configurations to enable the linkup automatically or detect indication of link drop to reset

Regards,

Sreenivasa

Hello John, 

Are you checking if there are some register configurations to enable the linkup automatically or detect indication of link drop to reset.

Regards,

Sreenivasa

Hello John, 

Do you have some inputs.

Regards,

Sreenivas