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  1. #1
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    PROCESSOR IS REBOOTING when hotplugging usb console to processor's Board through UART

    Hi All,

    while hotplugging(5-8 times) FTDI chip usb-uart console onto my laptop;
    the processor reboots, this rebooting process is intermittent.

    the processors uart lines are connected to the consoles uart lines(I/O level 3v3 both processor and console);

    currently on the uart's TX and RX lines both, there is a series 100 ohm and capacitance of 22pF to ground.

    Has anybody faced this similar issue ?
    How do i resolve this Rebooting issue, should i proceed with a diode array/ increase the capacitance?

    Thanks
    sush

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  2. #2
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    Re: PROCESSOR IS REBOOTING when hotplugging usb console to processor's Board through

    Hi,

    You talk about RS232 signal lines.

    But I think the signal lines do not cause the problem.
    I'm even not sure if it's a hardware problem at all.
    It may be a software problem:
    * OS, FTDI driver, the PC application .....

    But it may be a hardware problem, too.
    * try to disconnect/reconnect the RS232 lines while the according RS232_GND remains connected.
    * Try to disconnect/reconnect the USB while all the RS232 lines are not connected

    Klaus
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  3. #3
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    Re: PROCESSOR IS REBOOTING when hotplugging usb console to processor's Board through

    Hi Klaus,

    We don't have any onboard FTDI chip, we are using a external USB to UART converter(FTDI-232).

    We tried connecting and disconnecting, with GND line connected always, Still the board is Rebooting.

    We are using Processor IPQ4029 has anyone faced any issue on this chip?



  4. #4
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    Re: PROCESSOR IS REBOOTING when hotplugging usb console to processor's Board through

    Hi,

    We don't have any onboard FTDI chip
    I didn't talk about "onboard" either...

    Before you just talked about a laptop and FTDI....but now I have to assume it's not the laptop that is rebooting.
    You know ... any laptop has a processor inside....that may reboot.
    And most probably the problem is neither related to USB nor to the FTDI chip.

    *****
    Now to the IPQ chip .... isn't it an interface chip rather than a processor?

    And it seems you don't use true RS232.
    Many things are not clear to me.

    --> it's time for a somehow detailed drawing about your situation. All the way from laptop to target processor.
    With detailed informations about signals, levels, wiring...

    ***
    Still there is a good chance for a software problem.
    Disconnecting wires will cause some faulty signals .... causing timing, framing and parity errors.
    Maybe just the error handling is bad.

    Who designed the IPQ related hardware, who wrote the software?

    Klaus
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  5. #5
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    Re: PROCESSOR IS REBOOTING when hotplugging usb console to processor's Board through

    Hi Klaus,


    We successfully resolved the issue, we placed a 0.01uf cap on tx and rx lines;



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