Sniper2 , 04-06-2024, 04:31 PM
So i made a PCB with 2 ethernet PHY s and i have 2 problems with the board bring up:a phy 1 is recognised by MIO but does not establish a link to Ethernet b phy 2 is not detected by MDIO at allThe MDIO buss is shared and the signals are sent from the MPU and they look good , i even reduced the pull up resistor value to try and solve the problem but it did not .Also in a similar design it works but only sometimes as in i assembled 2 boards and 1 is fine and the other not ( rather only 1 phy works well).In regards to impedances and length matching i was very careful and did it well , the power supply (3v3) is a buck but measured noise was 30mV pp ( with long GND probe so real is less probably, the RMS noise was like 10mV or less ) .From what i managed to see from the registers of the working board the RX pins sense energy from my network so there seems to be no soldering problem or impedance since it works well at full speed. I am not sure what to look / try and do when debugging this PCB. Any advice?