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Electronics => Projects, Designs, and Technical Stuff => Topic started by: ricko_uk on March 31, 2022, 05:19:11 pm

Title: How to check if there is a good signal on LAN9514's downstream Ethernet port
Post by: ricko_uk on March 31, 2022, 05:19:11 pm

Hi,
I am using this hub chip LAN9514 that has a USB in and 4xUSB "out" and 1xLAN "out" (i.e. downstream ports). It is connected through another IC of the same type. So this one is further down the SBU tree.

The software guy has not developed any drivers/software yet. So, in order to test the PCB, how can I check if there is a good signal out of the LAN port without any software?

If I plug it into a router the LED on the router initially blinks on and off and then becomes stable on.  I assume that means the link is established and working.
But on the LAN9514 side the link LED keeps blinking on and off at random rates/intervals.

Any idea what that combination means? Is that enough to assume that the link is working correctly at least on the hardware or not?

I was thinking to perhaps buy a Ethernet tester like this one, but not sure if it would show anything?

https://www.amazon.co.uk/KOLSOL-Network-Standards-Distance-Function/dp/B08CMRCDNB/ref=sr_1_1_sspa?crid=10FAL9R96EXHJ&keywords=ethernet+tester+with+speed&qid=1648746613&sprefix=ethernet+tester%2Caps%2C110&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUE4NEczOE9BNEZJRUwmZW5jcnlwdGVkSWQ9QTAxNDE5OTUzTzI4T0hQUko2UlY4JmVuY3J5cHRlZEFkSWQ9QTAyNzk1NjkyUFRROFlKRkpTMDI0JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ== (https://www.amazon.co.uk/KOLSOL-Network-Standards-Distance-Function/dp/B08CMRCDNB/ref=sr_1_1_sspa?crid=10FAL9R96EXHJ&keywords=ethernet+tester+with+speed&qid=1648746613&sprefix=ethernet+tester%2Caps%2C110&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUE4NEczOE9BNEZJRUwmZW5jcnlwdGVkSWQ9QTAxNDE5OTUzTzI4T0hQUko2UlY4JmVuY3J5cHRlZEFkSWQ9QTAyNzk1NjkyUFRROFlKRkpTMDI0JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==)

Thank you :)

Title: Re: How to check if there is a signal on Ethernet port
Post by: tooki on March 31, 2022, 05:27:02 pm

Uh… connect your Ethernet port to a small Ethernet switch and see if the link status goes up? (I would assume that this would occur even without software initialization.)

Title: Re: How to check if there is a signal on Ethernet port
Post by: ricko_uk on March 31, 2022, 06:14:05 pm

Thank you Tooki,

I updated the OP...

If I plug it into a router the LED on the router initially blinks on and off and then becomes stable on.  I assume that means the link is established and working...

But on the LAN9514 side the link LED keeps blinking on and off at random rates/intervals.

Any idea what that means? Is that enough to assume that the link is working correctly at least on the hardware?

Thank you :)

Title: Re: How to check if there is a good signal on LAN9514's downstream Ethernet port
Post by: nctnico on March 31, 2022, 11:06:44 pm

Connect it to a switch without any network traffic to avoid blinking a combined link / activity LED.

Title: Re: How to check if there is a good signal on LAN9514's downstream Ethernet port
Post by: ricko_uk on April 01, 2022, 01:22:26 am

Thank you nctnico,
I did think so but wasn't sure that was 100% correct in all cases.