I have a bit of kit with an FPGA on it which includes an ethernet adapter. I'm trying to diagnose why it's not working and while I do that I've noticed that with an ethernet cable connected to my laptop, I see the network coming up and then dropping out again.
How does the hardware detect that the cable is plugged in? Is it watching for a clock sig
Best Answer
Point to point ethernet (not the old bus types) send link pulses to let the other end know something is connected. These are generated and detected in the phy layer. Ethernet interfaces often have a "link" LED near the connector. These are driven by the phy hardware when it detects link pulses from the other end.