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Intermittent drop of Ethernet transmit packets

element
Associate II
Posted on January 28, 2016 at 22:00

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1 REPLY 1
element
Associate II
Posted on January 29, 2016 at 07:48

I resolved a couple of issues which were affecting this problem and I wanted to follow up for anyone who comes upon this thread.

After logging the transmit descriptor status word value I discovered that collisions were occurring when packets were being dropped and that re-transmit was disabled.  Enabling re-transmit fixed the problem.

In addition I found that the the PHY_SR define in stm32_eth.h (from some reference source code) is PHY specific.  It was incorrect for the PHY I am using, so the duplex state was incorrect (thought it was half duplex, when in fact it was full duplex).  I just had to update the register, PHY_Speed_Status, and PHY_Duplex_Status defines to match that of the LAN8720A.

Best regards,

Element