W5500 No PHY Link

Projects Networking, Protocols, and Devices
1

Bit 0 of Register PHYCFGR of the W5500 does not indicate "link up" with ethernet cable connected when using the default "Link Status" example from the default ethernet library. I have verified SPI communication between the STM32F411CEU6 black pill board and the W5500 board with an oscilloscope and everything is as expected. Whatever I try the only thing that is returned is "Link status: OFF".

Troubleshooting steps I have tried so far:

  1. Verifying SPI communication is working
  2. Connecting to various devices:
  • Ethernet-> usb-c adapter dongle plugged into laptop
  • PC motherboard ethernet port
  • AX5400 Wifi router (verified to have auto-MDIX)
  1. Resetting W5500 during setup using RSTn pin, see code below

RigolDS7
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Screenshot of Oscope showing last bit of the last packet is 0 indicating "link down".

Hardware:
"Blackpill" STM32F411CEU6
W5500 Lite Breakout board

Wiring:

STM32F4 Pin Breakout Pin Name Oscope Channel
PA7 MO CH1
PA6 MI CH2
PA5 SCK CH3
PA4 CS CH4
PA3 RST none

W5500 datasheet

/*
  Link Status

  This sketch prints the Ethernet link status. When the
  Ethernet cable is connected the link status should go to "ON".
  NOTE: Only WIZnet W5200 and W5500 are capable of reporting
  the link status. W5100 will report "Unknown".
  Hardware:
   - Ethernet shield or equivalent board/shield with WIZnet W5200/W5500
  Written by Cristian Maglie
  This example is public domain.
*/

#include <SPI.h>
#include <Ethernet.h>

void setup() {
  digitalWrite(PA3, LOW);  // Reset W5500 
  delayMicroseconds(600);  
  digitalWrite(PA3, HIGH); 
  delay(1); 

  // You can use Ethernet.init(pin) to configure the CS pin
  //Ethernet.init(10);  // Most Arduino shields
  //Ethernet.init(5);   // MKR ETH Shield
  //Ethernet.init(0);   // Teensy 2.0
  //Ethernet.init(20);  // Teensy++ 2.0
  //Ethernet.init(15);  // ESP8266 with Adafruit FeatherWing Ethernet
  //Ethernet.init(33);  // ESP32 with Adafruit FeatherWing Ethernet

  Serial.begin(9600);
}

void loop() {
  auto link = Ethernet.linkStatus();
  Serial.print("Link status: ");
  switch (link) {
    case Unknown:
      Serial.println("Unknown");
      break;
    case LinkON:
      Serial.println("ON");
      break;
    case LinkOFF:
      Serial.println("OFF");
      break;
  }
  delay(1000);
}
2

Have you tried plugging it into a Hub or Switch? Going directly to your laptop you will need a crossover cable.

3

Thanks for the response! One of the devices I tried was my AX5400 Wifi router which I verified to have auto-MDIX. I was thinking that this ruled out the possibility that the cable was incorrect.

4

I am not familiar with that unit but it sounds like you are correct but it never hurts to try another cable.