Ethernet loosing link

[xRadx]

Hello guys,

I am facing an issue with Ethernet link on Nucleo F746ZG board.
The board was working correctly for many months, but recently it has stared loosing the link : LEDs are blinking, however it's not possible to connect to the boards, the board is not responding to ping and is not visible on router's connected devices list.

There were no changes to the board (HW or SW), some other devices were added to the network, but neither MAC or IP address is duplicated...

Anyone has some ideas of the reason or advice on how to start with troubleshooting this issue?

Thanks in advance

[fpistm]

Hi @xRadx
Are you able to test with an other board?

[xRadx]

Not with the same software, but the same libs/IDE compiled on the same PC I flash firmware on F767ZI. It works w/o any problems from 2months (so nut too long), but also different network.

The F746ZG was working fine for more than 1year...

So it would rather difficult to compare vs other boards etc. I am concern on how to try debug this issue...

[fpistm]

I am concern on how to try debug this issue...

Honestly don't know.
That's why I would suggest to test with an other board F746ZG to see if it is not simply a hw issue.
Example if you used the flash to store some data then at a certain number of iteration flash is no more usable like there is a life cycle of 10k write iteration (just an example).

[xRadx]

The flash is used only at the SW programming stage. Then no writing to the flash at all while a code is running...
I have this board from new and I've flashed it max 100 times. So i it's not this case.

Is there any spot in the lib code where it checks ethernet link periodically?

[fpistm]

The flash is used only at the SW programming stage. Then no writing to the flash at all while a code is running... I have this board from new and I've flashed it max 100 times. So i it's not this case.

OK. As stated just an example.

Is there any spot in the lib code where it checks ethernet link periodically?

Yes, it is called periodically thanks a timer interrupt;
https://github.com/stm32duino/STM32Ethernet/blob/b44edf68e1bb967b2a9df4b4e71c8d2e3ff70b0f/src/utility/stm32_eth.cpp#L318

[xRadx]

I bought another board the same type, but it also looses link...

Reset button does not help. Reconnecting ethernet cable makes even worst - LEDs go OFF and even reset button does not help...
Flashing firmware again also does not help.

The only trick that does the job is changing port on a network swtich the nucleo is connected to. But to the same switch are connected also other devices that works w/o any problems...

I will check if Nucleo will work on the new port and if not then I would try a different switch.

[xRadx]

Unfortunately either with any port and another switch nucleo looses the ethernet link.
I have even changed router, but nothing helps.

[fpistm]

Strange. If you change all hardware involved. There is probably something different than before. But hard to help.
Power?

[xRadx]

Tried many different power supplies and cables, but nothing helps... I am considering rather software issue, because any other boards (ESP32 and Arduino with ethernet Wizz shields and any other devices in the network) programmed via Arduino IDE work just fine...
Unfortunately I think I might have no enough knowledge to debug it..

[fpistm]

Well you told:

The board was working correctly for many months,

So if you do not change the firmware why it fails now? From my point of view it seems more a Hardware problem.
Or something in the code made it fails 3 months later (RTC usage ?)

[xRadx]

Some time has passed and I have an update:
I started with WebServer example from STM32Ethernet library: first change was PinMap:

const PinMap PinMap_Ethernet[] = {
  {PA_1,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PA_2,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PA_7,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PB_13,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PC_1,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PC_4,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PC_5,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PG_11,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PG_13,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {NC,        NP,  0}
};

and with this change my nucleo F746ZG was working 3days w/o visible interrupts.

With a next change I did set almost all free pins to inputs so the final code is:

typedef struct
{
  int pin;
  int out;
}inp_t;

inp_t IN[80];

const PinMap PinMap_Ethernet[] = {
  {PA_1,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PA_2,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PA_7,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PB_13,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PC_1,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PC_4,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PC_5,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PG_11,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {PG_13,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)},
  {NC,        NP,  0}
};


#include <LwIP.h>
#include <STM32Ethernet.h>

IPAddress ip(192, 168, 1, 177);
EthernetServer server(80);

void setup() {
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

initInputs();

  Ethernet.begin(ip);
  server.begin();
  Serial.print("server is at ");
  Serial.println(Ethernet.localIP());
}


void loop() {
  EthernetClient client = server.available();
  if (client) {
    Serial.println("new client");
    bool currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        Serial.write(c);
        if (c == '\n' && currentLineIsBlank) {
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println("Connection: close");  // the connection will be closed after completion of the response
          client.println("Refresh: 5");  // refresh the page automatically every 5 sec
          client.println();
          client.println("<!DOCTYPE HTML>");
          client.println("<html>");
 
         for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
            int sensorReading = analogRead(analogChannel);
            client.print("analog input ");
            client.print(analogChannel);
            client.print(" is ");
            client.print(sensorReading);
            client.println("<br />");
          }
          client.println("</html>");
          break;
        }
        if (c == '\n') {
          currentLineIsBlank = true;
        } else if (c != '\r') {
          currentLineIsBlank = false;
        }
      }
    }

    delay(1);
    client.stop();
    Serial.println("client disconnected");
  }
}


void initInputs(void)
{
  IN[0].pin = PC6;
  IN[1].pin = PB12; //
  IN[2].pin = PB11; //
  IN[3].pin = PB2;
  IN[4].pin = PB1;
  IN[5].pin = PB15;
  IN[6].pin = PF5;
  IN[7].pin = PF4;
  IN[8].pin = PE8;
  IN[9].pin = PF10;
  IN[10].pin = PE7;
  IN[11].pin = PD14;
  IN[12].pin = PD15;
  IN[13].pin = PF14;
  IN[14].pin = PE9;
  IN[15].pin = PE11;
  IN[16].pin = PF3;
  IN[17].pin = PF15;
  IN[18].pin = PF11;
  IN[19].pin = PE0;
  IN[20].pin = PG8;
  IN[21].pin = PG5;
  IN[22].pin = PC9;
  IN[23].pin = PA5;
  IN[24].pin = PA6;
  IN[25].pin = PB6;
  IN[26].pin = PC7;
  IN[27].pin = PB10;
  IN[28].pin = PB4;
  IN[29].pin = PB5;
  IN[30].pin = PA3;
  IN[31].pin = PD13;
  IN[32].pin = PD12;
  IN[33].pin = PD11;
  IN[34].pin = PE10;
  IN[35].pin = PE12;
  IN[36].pin = PE14;
  IN[37].pin = PE15;
  IN[38].pin = PE13;
  IN[39].pin = PF13;
  IN[40].pin = PF12;
  IN[41].pin = PG14;
  IN[42].pin = PD10;
  IN[43].pin = PG4;
  IN[44].pin = PC0;
  IN[45].pin = PD3;
  IN[46].pin = PG2;
  IN[47].pin = PG3;
  IN[48].pin = PE2;
  IN[49].pin = PE4;
  IN[50].pin = PE5;
  IN[51].pin = PF2;
  IN[52].pin = PF8;
  IN[53].pin = PF9;
  IN[54].pin = PG1;
  IN[55].pin = PE6;
  IN[56].pin = PG15;
  IN[57].pin = PG10;
  IN[58].pin = PF6;
  IN[59].pin = PF7;
  IN[60].pin = PA15;
  IN[61].pin = PC2;
  IN[62].pin = PC3;
  IN[63].pin = PD4;
  IN[64].pin = PD5;
  IN[65].pin = PD6;
  IN[66].pin = PD7;
  IN[67].pin = PE3;
  IN[68].pin = PF1;
  IN[69].pin = PF0;
  IN[70].pin = PD1;
  IN[71].pin = PD0;
  IN[72].pin = PG0;
  IN[73].pin = PE1;
  IN[74].pin = PG9;
  IN[75].pin = PG12;

  for (uint8_t i = 0; i < 76; i++)
  {
    pinMode(IN[i].pin, INPUT_PULLUP);
  }

}

and with this the ethernet brakes after a while...

After I have updated the STM32duino core to the latest it even goes down earlier (maybe by chance)...

Any idea what's the reason?

[fpistm]

Hard to tell.
So If I well understand when you init all pins listed in INPUT_PULLUP your code break?
Why use INPUT_PULLUP ?
I would recommend INPUT_ANALOG to avoid any power consumption (which is the default state).
You can aslo try to add Serial.flush(); after each last serial print to avoid any IT issue.

[xRadx]

I use INPUT_PULLUP (instead just INPUT) because to the pins are connected such a mechanical buttons that when not pressed then the pin is floating (causing random readings) and when is pressed then connected/shorted to GND.

I did not check if this particular INPUT_PULLUP is causing the Ethernet breakage or the problem is when all of these or maybe some particular pins from listed are initiated anyhow (OUTPUT/INPUT or anything else). I will check that.

I have noticed that core default Ethernet pin map is much wider (more pins are involved), but according to the schematic - only these I entered are connected. But maybe some others are used...

WEAK const PinMap PinMap_Ethernet[] = {
  {PA_0,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_CRS
  {PA_1,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_REF_CLK
  {PA_1_ALT1, ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_RX_CLK
  {PA_2,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_MDIO
  {PA_3,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_COL
  {PA_7,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_CRS_DV
  {PA_7_ALT1, ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_RX_DV
  // {PB_0,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_RXD2
  // {PB_1,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_RXD3
  // {PB_5,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_PPS_OUT
  {PB_8,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TXD3
  {PB_10,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_RX_ER
  {PB_11,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TX_EN
  // {PB_12,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TXD0
  // {PB_13,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TXD1
  {PC_1,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_MDC
  {PC_2,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TXD2
  {PC_3,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TX_CLK
  {PC_4,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_RXD0
  {PC_5,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_RXD1
  {PE_2,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TXD3
  // {PG_8,      ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_PPS_OUT
  {PG_11,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TX_EN
  {PG_13,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TXD0
  {PG_14,     ETH, STM_PIN_DATA(STM_MODE_AF_PP, GPIO_PULLUP, GPIO_AF11_ETH)}, // ETH_TXD1
  {NC,        NP,  0}
};

Thanks for the hint with Serial.flush();