Problem With W5100 Linking to Ethernet.

Question

Hi. I have created my own board using the W5100 and Atmega2560. I can Communicate to the Wiznet w5100 via SPI. but cannot connect to Ethernet. One Strange thing is, The SPD Led lights up on power-up with no Ethernet cable connected. ( Is this a fault condition?) I also do not get a link LED to light up when I plug in an Ethernet cable to a network switch. I can write the mac and IP address to the W5100 and can also read back the IP address from the chip. Could the chip be faulty? Please see attached, my schematic. I am using the TRXCOM TRJ16211 Mag Connector that has a centre tap for the TX and RX transformer. I have connected these together and linked them to 3.3VA Schematic.pdf (159.0 KB)

Eugeny · Answer

You left pin 33 (VCC1V8D) unconnected. Please refer to the reference circuit diagram. You circuit driving SEN pins looks strange. You do not plan to use chip in parallel access mode, why you complicate the circuit? If you use SPI only, pull SEN up.