(Schematic in next post because I can’t post more than 2 links)
When I switch on the board, the LINK LED is off. When I plug a cable into the RJ45 connector, the LINK LED starts to flash on and off at a fixed rate (at about 0.5 Hz). In this time, nothing happens in terms of network communication as far as I can tell: on my network switch - which the RJ45 cable is connected to - the “ACT” LED does not come on, indicating no activity. The ACT LED on the RJ45 connector also never comes on. However, since the LINK LED starts to flash when I plug the cable in, I figure something is happening, but is not fully working.
Since having made the board, I have discovered three potential issues:
- I did not use a 12k4 resistor at EXRES1 (pin 10 of the W5500), but rather a 10k resistor. I am not sure if this matters.
- The SCSn chip select pin on the W5500 is not pulled up to Vcc, but instead is connected directly to the microcontroller (an Atmel ATmega32U4). I notice in the Arduino schematic that this is pulled up via a 10k resistor. However, I hacked a 10k resistor on to the board but this doesn’t seem to fix it. (The SPI bus is not shared with any other device).
- I have not added 10k resistors to ground on the “RSVD” pins of the W5500. The Arduino schematic does this, but the Wiznet example does not, so I guess it doesn’t matter.
Does anyone have any ideas what is going on?