Dual port ethernet

[ACohe.3]

Hey,
I use STM32H745, I created ETH communication on the M4 core and it works well.
Now I want ETH communication with two ports, one port per core.
It is possible?

In each core before the main while, I do:
MX_LWIP_Init();

/* create new tcp pcb */
tcpb = tcp_new();

err_t err;
if (tpcb != NULL)
{
//err_t err;

/* bind echo_pcb to IP and PORT (ECHO protocol) */
err = tcp_bind(tpcb, &ipaddr, SysIP.PORT);

if (err == ERR_OK)
{
/* start tcp listening for echo_pcb */
tcpb = tcp_listen(tcpb);

/* initialize LwIP tcp_accept callback function */
tcp_accept(tpcb, PC_tcp_accept);
}
else
{
/* deallocate the pcb */
memp_free(0, tpcb);
}
}

And inside the main while, I execute MX_LWIP_Process();

For M4 core: SysIP.PORT == 4949.
For M7 core: SysIP.PORT == 4950.
IP ADDRESS, NETMASK ADDRESS and GATEWAY ADDRESS are the same for both cores.

I have no ping at all when I try to create this way.

What am I doing wrong? What should I do differently? Need to change something in CubeMX?

Thanks for the helpers!

[Andrew Neil]

Use this button to properly post source code:

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[ACohe.3]

void PC_tcp_init(void)
{
	/* create new tcp pcb */
	tpcb = tcp_new();

	err_t err;
	if (tpcb != NULL)
	{
	  //err_t err;

	  /* bind echo_pcb to IP and PORT  (ECHO protocol) */
	  err = tcp_bind(tpcb, &ipaddr, SysIP.PORT);

	  if (err == ERR_OK)
	  {
		/* start tcp listening for echo_pcb */
		tpcb = tcp_listen(tpcb);

		/* initialize LwIP tcp_accept callback function */
		tcp_accept(tpcb, PC_tcp_accept);
	  }
	  else
	  {
		/* deallocate the pcb */
		memp_free(0, tpcb);
	  }
	}
}

MX_LWIP_Init();
PC_tcp_init();

while(1)
{
	MX_LWIP_Process();
}

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[Bob S]

I have limited experience with STM32 dual-core CPUs, but I believe that you cannot map a single peripheral (i.e. ETH) to both cores.  It needs to be mapped/assigned to one core, and that core needs to handle the low-level ethernet stuff (i.e. ETH hardware config and IRQ handler).  Then that core decides whether to send incoming packets to its own LwIP stack or somehow pass it to the other core.  Likewise, there needs to be code to allow the 2nd core to "send" outgoing packets to the 1st core to actually send them.  AFAIK that will be custom code in the LwIP low-level input and output functions.

[ACohe.3]

In general, is it possible to configure two ports in an STM32 MCU?
Have you seen an implementation of this before?

[Bob S]

Two (or more) IP ports, yes.  You can open many IP ports at the same time (as long as you have LwIP configured to have enough buffers).  You just need a bind() call for each port and provide code to service each one.  I do this all the time.

[Andrew Neil]

There are Ethernet controllers which connect via SPI (and other interfaces) - you could use them to add extra physical interfaces?

And there are things like Wiznet & Lantronix which offload the whole IP stack; eg,

https://www.carminenoviello.com/2015/08/28/adding-ethernet-connectivity-stm32-nucleo/

https://www.lantronix.com/products-class/wired-modules/

[Andrew Neil]

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@ACohe.3 wrote:

Now I want ETH communication with two ports, one port per core.

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Why?

Wouldn't it make more sense to have just one Ethernet port, and have the 2 cores communicate over internal inter-core interfaces?