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Thread: Change the IP of Teensy 4.1 using UDP (again)

  1. #1

    Change the IP of Teensy 4.1 using UDP (again)

    Using an SPI with the teensy 3,2, I can change the IP relative easily from say 192.168.1.236 to .237 but when I do it with the 4.1, it does not respond to the new IP address.

    This code works for me with Teensy3.2 Any suggestions?. It's not a deal breaker but would be nice to get it to work.

    Thanks,

    Simon

    Udp.stop();
    Ethernet.begin(mac, new_ip);
    Udp.begin(localPort);

    PS: Asked before but no one responded.

  2. #2
    you are stopping udp but not ethernet, I don't know if you can actually change that live?
    In my project I do reboot teensy after applying any change, so it restarts fresh with all the new settings saved in memory.
    I don't know if that's a possible workaround for you. The command I use is CPU_RESTART;

  3. #3
    Hi,
    Thanks. I can actually write the ip to flash and re-start but I was hoping to be able to just change it without loosing other variables etc. It DOES work with the Teensy 3.2 and the WizIO over SPI so I was just wondering if anyone had an idea. It's not a deal breaker.

    Obviously I am using the native ethernet headers. Also seems to hang when you check if the cable is plugged in (if it isn't) but the 3.2 didn't. Again not a deal breaker just would like it to work.

    Maybe I should digging into the sources :-)

    Thanks
    Simon

  4. #4
    Quote Originally Posted by SimonWakley View Post
    Hi,
    Thanks. I can actually write the ip to flash and re-start but I was hoping to be able to just change it without loosing other variables etc. It DOES work with the Teensy 3.2 and the WizIO over SPI so I was just wondering if anyone had an idea. It's not a deal breaker.

    Obviously I am using the native ethernet headers. Also seems to hang when you check if the cable is plugged in (if it isn't) but the 3.2 didn't. Again not a deal breaker just would like it to work.

    Maybe I should digging into the sources :-)

    Thanks
    Simon
    yes, the cable requirement is also a bug of the native library, there is a workaround but you have to change the library:
    https://github.com/vjmuzik/NativeEthernet/issues/12

  5. #5
    Senior Member
    Join Date
    Mar 2017
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    Oakland, CA, USA
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    You should be able to call Ethernet.setlocalIP() (https://www.arduino.cc/en/Reference/EthernetSetLocalIP)

    Note: Iíve got another library, QNEthernet, that doesnít block when thereís no cable attached. Itís based on lwIP, as an alternative.

  6. #6
    Senior Member
    Join Date
    Apr 2014
    Location
    Cheltenham, UK
    Posts
    365
    This is worth a read.
    Seems that IwIP was developed for use in embedded systems (sounds familiar).
    @shawn how does IwIP compare with uIP?

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