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Cannot connect to my router

Discussion in 'Microcontrollers, Programming and IoT' started by muzun, Jul 20, 2018.

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  1. muzun

    muzun

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    Jul 13, 2018
  2. kellys_eye

    kellys_eye

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    Swap the Rx and Tx connections
     
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  3. muzun

    muzun

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    Jul 13, 2018
    What do you mean ? Now I connect TXD to RX and RXD to TX and GND to GND, and not using 3.3V and 5.0V.
    You mean I need to use TXD to TX and RXD to RX ? or try other cables ? I
     
  4. muzun

    muzun

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    Jul 13, 2018
    [​IMG]
    Router 3.3v pin si giving 0.0
    RX and TX are okay
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Yes. This is always the first thing to try when RS-232 is not communicating at all.
     
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  6. kellys_eye

    kellys_eye

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    You do not need to connect the 3.3V line - just the two GND's between devices and the TX and RX lines.
     
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  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    You can also use a led and a resistor to determine unambiguously which is the transmit pin.

    This varies a little depending on whether you have real RS-232 or a logic level alternative (the latter is most common these days).

    Place a 470Ω resistor in series with a pair of LEDs connected in inverse parallel (this simply means you don't have to worry about polarity). Connect one wire to the pin in question and the other to ground. If neither led lights, leave one lead on the pin in question and move the other to the positive power supply. If either led lights in either position, this is an output pin. If it doesn't light then it is either an input or not connected.

    Once you have identified the output pins you know what the actual tx pin is. Connect tx to Rx and vice versa. Just to be amusing, sometimes the tx pin is marked Rx because they want you to connect Rx to it.
     
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  8. kellys_eye

    kellys_eye

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    Doesn't that just hack you off at times.....:p
     
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  9. muzun

    muzun

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    Jul 13, 2018
    I know, but is it okay tha 3.3v is giving 0.0v ?

    Tried TXD to TX and RXD to RX and vice-versa, same blank window

    Router leds are lighting power and if case I connect patch cord it lights too
     
    Last edited: Jul 21, 2018
  10. Alec_t

    Alec_t

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    Jul 7, 2015
    Sounds like a faulty unit, unless it has some enabling/disabling function.
     
  11. muzun

    muzun

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    Jul 13, 2018
    I bricked it when was trying to flash it using SSH, not UART. But leds are working so it's not completely bricked
    How do think it will be possible to fix this if I give router to some service center ?
     
  12. Alec_t

    Alec_t

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    It will be cheaper to buy a new router than getting it fixed.
     
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  13. davenn

    davenn Moderator

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    well you didn't tell us that in your opening post,.
    That would have been very helpful info and would have saved wasting everyone's time with the advice Steve and Kelly gave you above.
    which was pointless :rolleyes:

    So you are really dealing with crashed firmware rather than a hardware fault … chances are it is permanently bricked.

    time for a new router, and lesson learnt ;)
     
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  14. muzun

    muzun

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    Jul 13, 2018
    Just on other forum they said it's permanently bricked if leds are not working, but if leds are working when you turn it on and connect patch cords then it can be unbricked.
    Okay thanks.
     
  15. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    It's a bit suspicious if the 3.3V pin reads 0V though. This may be by design, or it may indicate a problem.

    Perhaps on the other forum you can enquire if this is expected.
     
  16. totalmedtech

    totalmedtech

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    Jul 19, 2018
    i suggest you get a multimeter and check some values,it could be an easy fix;)(trace from the power source check if everything is in one piece)
     
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