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Re: [lwip-users] Randomly delayed frame (STM32070 package including LwIP

From: Jason White
Subject: Re: [lwip-users] Randomly delayed frame (STM32070 package including LwIP v1.4.1)
Date: Fri, 4 Jan 2019 15:52:39 -0500

It makes sense.

We use the DP83848 in full duplex mode on several products (thankfully) with
no problems. 

Out of curiosity what are you working on? (if you are able to share)

-Jason White

-----Original Message-----
From: lwip-users <address@hidden> On
Behalf Of stevestrong
Sent: Friday, January 4, 2019 3:15 PM
To: address@hidden
Subject: Re: [lwip-users] Randomly delayed frame (STM32070 package including
LwIP v1.4.1)

Jason, thanks for your comment.

I saw that no Rx packets were ever lost, no Rx/TX buffer over- or under-flow
ever occurred.
That finally made me think on DMA and PHY.
I realized that currently my PHY works in 100Mbp half-duplex mode, and that
could eventually be a problem, when many packets arrive and the PHY tries to
send some data in the same time (although the PHY should probably manage

Then I found on Internet a site which offers a solution for DP83848, a patch
for MBED ETH lib, to work in full-duplex mode.

I implemented it, and ... voila: no more lost packets in 100 tries!
No more delayed packets. Success!

So I can conclude that the issue was most probably due to the heavy traffic
when PHY is working in half-duplex mode.
Does this make sense?

Anyway, thank you all for the invested time and effort, I really appreciate


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