Other Parts Discussed in Thread: DP83825
Hi,
I'm currently working to integrate a DP83825I into a design that uses and ESP32 as the main controller. The ESP has an integrated MAC which I am using to communicate and control the PHY. To be clear MDIO is working as expected. I can control and inspect the status of the PHY from the MAC but frames transmitted from the MAC to the PHY rarely seem to make it intact. I've tried a couple different revisions to get the MAC and PHY communicating properly over the RMII link, But thus far have come up empty. I initially tried designing the RMII link without termination resistors as they're supposed to be integrated into the PHY but I noticed a fair amount of over and undershoot not only on the data lines but also the clock line from the ESP to the PHY. The second revision includes some 33 ohm series termination which has helped with the extra noise a little but the RMII link still isn't working as expected. What's the recommended layout for the RMII signal traces? I've attached the relevant section of my layout which shows how the RMII link is laid out. Any help with this would be much appreciated. One interesting thing to note is that when I probe the clock line from the ESP to the PHY with my scope, the PHY starts to receive some of the frames from the MAC in the ESP, so there definitely seems to be something incorrect with my layout.
Thanks, Neil.