WIZnet Developer Forum

Speed and Link LEDs blink slowly when connected to gigabit

I have used the W5200 in a product design. We have produced roughly 50 boards so far that have had no issues. But recently we have produced 11 boards that have a problem.

When these boards are connected to a 1000Base-T LAN the Link and Speed LEDs both blink together at approximately 1Hz. When these same boards are connected to a 10/100 switch the problem goes away - they work fine at 100Base-T. I understand that this part will only operate at 10 or 100Base-T, but when connected to a 1000Base-T LAN it should still operate at 100Base-T

We are driving the Auto Negotiate (29), Duplex (30), and Speed (31) pins high - so auto negotiation should be enabled, it should be in full duplex mode, and 100Base-T mode should be enabled.

I saw some similar posts on other bulletin boards but didn’t find any conclusive answers. Has anyone else run into this?

This blinking sequence evidently serves some diagnostic purpose, does anyone know what it means?

What do the package markings on the W5200 mean? How can I determine what batch my parts were made in / what version of the silicon I am using?


Dear newaters,

Could you send the schematic of W5200 ?
When W5200E01-EVB is connected to a 100Base-T LAN, Speed and Link LEDs is O.K…


When connecting to a 100Bate-T LAN everything works fine for me to… it is when I connect it to a gigabit LAN that I have issues. But the issues are with some of my boards.

I have attached the Ethernet page of my schematic. All of the off page connectors on the left run directly back to my uC to GPIOs or my serial interface.

Dear newaters,

Thanks to send schematic. We will review and reply.

We knew that your problem happened on Gigabit and checked gigatib and 100Base-T connection.


Dear newaters,

Could you let us know the date code of W5200 ?
It has 4 digits on the chip surface.
For example , 1319 or …


I finally have a PCB that is doing this in my possession. The four digits on the surface are 1323.

update: This issue no longer just pertains to gigabit peers. I am having issues even auto negotiating at 100BaseT with a phy test tool on some units.

This question can be answered by going on the following URL.

[url]Frequency Stability]

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