STM32H7 and LWIP settings for 2 simultaneous connections.

[Muhammed Güler]

Hello to everyone,

I found LWIP settings working fine with 2 ports open at the same time. I want to share with you. I am working with the NUCLEO-H753ZI board.

in addition to the manual here.

I shifted the Ethernet and LWIP buffers to addresses 0x30000000 and 0x30004000. I installed the MPU in two ram regions of 64K and 256B starting from 0x30000000 as follows.

I got most settings from LwIP_HTTP_Server_Netconn_RTOS app. I increased some values ​​until it works stable.

I set MEMP_NUM_TCP_PCB to 10.

I set MEMP_NUM_UDP_PCB to 6.

Since it is not clear which setting will consume how much ram in the manuals, I set MEM_SIZE to 32768 bytes.

I set TCP_MSS to 1460 bytes.

I set PBUF_POOL_BUFSIZE to 1528 bytes.

I set TCP_WND and TCP_SND_BUF to 5840 bytes (4*TCP_MSS)

Cubemx set TCP_SND_QUEUELEN to 17 bytes.

I set MEMP_NUM_TCP_SEG to 24.

From advanced parameters;

I have enabled LWIP_TCPIP_TIMEOUT, LWIP_SO_SNDTIMEO, LWIP_SO_RCVTIMEO so that the ports can be closed if the connection is lost.

I know very little about LwIP. but with these settings, I can work from two different ports without losing packets.

I have written C# applications that query again for each port when the answer is received. In the scenario where I made a total of 5k queries per second from two applications, it worked for 2 days without any packet loss.

[simosilva]

Thanks for sharing!

[NLong.1]

Thank you so much for this! But can I ask some little questions cause I'm so new to LwIP. Have you ever tried to receive a packet that has a size larger than TCP_MSS yet? I can not receive the whole response from the server (2.75KB), I just received only 1440 Bytes. Are there any ways to receive full the response data? Can someone help me with this?

[Muhammed Güler]

My homepage is 2.5k in size, I am sending it with the code below.

I am using socket communication.

void BulkWrite(int conn,char *Buffer,int size)

{

  if(size<1400)

  {

    write(conn, Buffer, size);

  }

  else

  {

    write(conn, Buffer, 1400);

    BulkWrite(conn,&Buffer[1400],size-1400);

  }

}