Bad characters on U-boot using UART interface



  • Hi.
    I've got the following problem. I'm trying to flash the firmware from my USB drive. So I press the "Reset" button and see that LED starts blinking. My COM port is opened via Putty. However, I see strange characters although some characters seem to be correct. I'm trying to press "1" or "2" option but without any success.
    0_1559908670568_52e09e18-3bd0-4834-b25c-edbc66a9ec5c-image.png
    When the bootloader is loaded (after 40 seconds) it starts to uncompress image. Then everything is OK.
    0_1559908726725_4c7e1381-a115-4256-bc1c-0b793477d777-image.png
    What is wrong with the UART and bootloader? There is some noise. I've tried to connect UART pins directly with my UART-USB adapter but it didn't help. Also, I'd like to mention that I didn't change the bootloader.



  • @Artem-Kramov
    Assuming you are using an Onion Expansion or Mini dock, are you using the required driver and speed as detailed in Serial on a Windows Device?



  • I'm using the required driver CH340 on my Windows PC



  • @Artem-Kramov
    A while back I had a similar problem. I was using an Omega2+ with a power dock. I had connected the serial via ftdi-usb to my PC with Putty as my terminal. I checked drivers, speed, parity etc. but still had a display just like yours. Eventually it turned out to be a bad ground connection between the dock and ftdi.



  • @Michael-Lynch
    Thank you very much! I'll try your suggestion and respond if it works.



  • @Michael-Lynch
    Sorry for such delay - I was fighting against this problem. Your suggestion was hopeful but it didn't help me. I hope your suggestion will help other people who will face this kind of problem.
    I've suddenly noticed that I can see correct symbols of bootloader output on the baud rate 120000 (instead of expected 115200). However, the baud rate of the kernel has to remain 115200. Firstly I thought that it is a manufacturing defect but I've noticed such a thing on the few devices. Also, I've entered into the console mode of the bootloader: the expected baud rate is 115200 (variable baudrate=115200).
    @Omega-Squad , @administrators @cas
    I'm using Omega2+ devices. What is the reason for this bug? I'm a little bit confused about how to deal with this problem. I hope for your understanding.


  • administrators

    @Artem-Kramov What does your hardware setup look like? Are you using an Expansion Dock or a Mini Dock?



  • @Lazar-Demin OP "told" us a few backround info too

    • he has an Omega2+ with FW ???
    • I guess - he has no dock or maybe has some custom dock
    • he has a CH340 USB-to-serial module / cable, it seems the Omega Tx -> PC Rx connection is broadly OK
    • he has a Windows ??? PC with PuTTY

    I think he has some hardware problem - so the

    What does your hardware setup look like?

    is a very good question.



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