Wi-Fi® + Bluetooth® + 802.15.4のトピックRe: RW612 echo_tcp_client Lwip Connect Problem

RW612 echo_tcp_client Lwip Connect Problem

Dr_Ron — Mon, 20 Apr 2026 01:30:28 GMT

I am unable to get the shell command "echo_tcp_client" in example project "frdmrw612_lwip_ipv4_ipv6_echo_freertos" to connect to a PC using the FRDM-RW612 development board.

I am using version v25.6 of MCUXpresso IDE. I am also using version 26-03-00 of the SDK for the RW612 board.

My PC has a fixed IP address of 196.168.0.100. The RW612 board uses address 198.168.0.102. I am using port 50000.

I use an older Linksys AP/Router, model WRT54GS v.2 for network connections. RW612 Wi-Fi works well with this device. I have also tried a newer AP/Router, NETGEAR model R6220.

The shell command "echo_tcp_server" works as designed as shown below which demonstrates the PHY got configured correctly and is functional.

SHELL>> echo_tcp_server 50000

Creating new socket.

Waiting for incoming connection. Use end command to return...

ECHO_TCP_SERVER>>

Accepted connection

Echoing data. Use end command to return...

5B sent back.

For the "echo_tcp_server" command, I use the ncat command on my PC Command Window as shown below:

C:\Users\RonL>ncat -v 192.168.0.102 50000

Ncat: Version 7.98 ( https://nmap.org/ncat )

Ncat: Connected to 192.168.0.102:50000.

hello

Ncat: 5 bytes sent, 5 bytes received in 22.89 seconds.

I can also use a Python program snippet to communicate with the "echo_tcp_server" as shown below:

s2 = socket.create_connection(("192.168.0.102", 50000))

while True:

message = input("Input a message to send >")

if message == "close":

s2.close()

break

else:

s2.send(message.encode())

All of this works well with the "echo_tcp_server" in example project "frdmrw612_lwip_ipv4_ipv6_echo_freertos".

However, if I now try to send something to a server using the "echo_tcp_client" command, the connection to the client never occurs.

Here is ncat on my Windows Command Window setup as a server:

C:\Users\RonL>ncat -v -l -p 50000

Ncat: Version 7.98 ( https://nmap.org/ncat )

Ncat: Listening on [::]:50000

Ncat: Listening on 0.0.0.0:50000

Here is the "echo_tcp_client 192.168.0.100 50000" command executed on the RW612 board:

SHELL>> echo_tcp_client 192.168.0.100 50000

Creating new socket.

Connecting...

Connecting failed. errno=103

As can be seen, the connection never takes place from the RW612 generating the error #103 (software error).

A similar Python snippet below behaves the same way.

with socket.create_server(("", 50000)) as s:

#s.setblocking(False)

s.listen(1)

while True:

print("Waiting for client to send a message")

comm, addr = s.accept()

while data := comm.recv(1024):

print("[{}] {}".format(addr[0], data.decode()))

I am certain that the ncat commands that I am using are correct as well as the Python program code snippets because these all work with the example project "frdmrw612_wifi_ipv4_ipv6_echo" for both server and client connections. This project does not use the PHY.

The above error with the "echo_tcp_client" seems to be generated in the lwip command "lwip_connect()". This command then calls the function "netconn_connect()" It is in this function that I see a delay followed by the error 103.

There should be no doubt that the router and cables that I am using are all functional because data is transmitted correctly with the "echo_tcp_server" command. I can successfully ping the RW612 board from the Windows Command window.

Can you help me determine the code to fix in this project to get the "echo_tcp_client" working?

Thanks,

Dr_Ron

Re: RW612 echo_tcp_client Lwip Connect Problem

RomanVR — Mon, 27 Apr 2026 23:15:28 GMT

Hi @Dr_Ron, sorry for the delay.

Would you please share logs of the serial terminal of the behavior that you are watching when trying to connect as client?

Thank you!

Re: RW612 echo_tcp_client Lwip Connect Problem

Dr_Ron — Tue, 28 Apr 2026 15:43:26 GMT

RomanVR:

I have already provided you with all the serial logs associated with this "echo_tcp_client" problem with LwIP on the RW612.

Here is the main serial output when the problem occurs:

SHELL>> echo_tcp_client 192.168.0.100 50000

Connecting...

Connecting failed. errno=103.

For your information, I have been exploring possible issues with FreeRTOS. This project appears to not set a reasonable heap size. I recently changed the FreeRTOS heap size to 100,000 and changed to heap scheme 4 as shown below. However, this did not fix the problem. I am now exploring possible issues with LwIP and its configuration.

In file: "FreeRTOSConfig_Gen.h"

#define configTOTAL_HEAP_SIZE 100000
#define configFRTOS_MEMORY_SCHEME 4

Thanks for addressing this issue. I hope that we can find a solution to it.

Dr_Ron

Re: RW612 echo_tcp_client Lwip Connect Problem

RomanVR — Tue, 28 Apr 2026 23:52:37 GMT

Hello @Dr_Ron.

Sorry for not being clear before, I meant to ask you to please share logs with debug macros enabled to have a better insight of this behavior.

You may enable these debugging macros in the lwipopts_gen.h file inside the source folder of the project.

Thank you.

Re: RW612 echo_tcp_client Lwip Connect Problem

Dr_Ron — Wed, 29 Apr 2026 01:06:14 GMT

@RomanVR

You are going to have to tell me which of the hundred or so defines in the lwipopts_gen.h file to enable/disable or send me a copy of your file for me to use. I don't know which ones to change to enable the logging that you want.

Re: RW612 echo_tcp_client Lwip Connect Problem

RomanVR — Thu, 30 Apr 2026 21:36:50 GMT

Hello @Dr_Ron.

Would you please confirm if the tests that you have been doing were done with a corporate computer? Sometimes corporate devices are secured, and this may be causing the connection abortion.

I have tried to run the example with my personal laptop, and I was able to connect the board with the echo_tcp_client command.

Re: RW612 echo_tcp_client Lwip Connect Problem

Dr_Ron — Fri, 01 May 2026 02:07:29 GMT

Hello @RomanVR

I am using my personal computer for these tests not a corporate computer. Also, my router is on my desktop and is ONLY connected to the PC and the RW612 board. I'm pretty sure that all of the IP addresses are correct.

What seems strange here is that the equivalent WiFi project has both the server and client echo tests working. Also, the example HTTP Server project works perfectly, demonstrating that to/from communications with the RW612 board are working.

Let me try a different PC and a different router to see if I can get the echo_tcp_client to work.

Please be aware that the error message that is being generated on my system is not a "connection" error. It is a "software" error.

Let me get back to you after a few more experiments.

@Dr_Ron

Re: RW612 echo_tcp_client Lwip Connect Problem

Dr_Ron — Tue, 05 May 2026 02:31:39 GMT

Hello again @RomanVR

I have determined the problem associated with "echo_tcp_client" command in the LwIP Echo project.

The problem is due to the IP address that NXP is using for the RW612 board. This fixed address is located in file "app.h" and is currently set to 192.168.0.102.

The problem that I believe with using this address is that some AP/Routers use this address internally and causes a conflict when the RW612 board tries to use this address.

When I set this address to 192.168.1.102, everything is now working. Also, using this address in the LwIP Ping project makes that project start to work also.

The reason that the original IP board address of 192.168.0.102 works for your team is because your AP/Routers behave differently than the two IP/Routers that I have.

NXP may want to consider updating the LwIP projects in the next SDK so that others don't experience this problem.

The RW612 board is an awesome board using the M33 processor and the external flash memory. The fact that it does both 2.4 and 5 MHz allows for a lot of wireless flexibility that your competitors don't have.

Thanks for your help.

@Dr_Ron

Re: RW612 echo_tcp_client Lwip Connect Problem

RomanVR — Tue, 05 May 2026 15:13:37 GMT

Hello @Dr_Ron,

Thanks for your feedback, glad to know that you got the example working properly now.