Home Forums Hardware discussions Serial over USB not working.

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    I am having trouble with my unit.
    I never could get the serial over usb to work with only the 5v power plugged in, it would show up as a device, but the terminal would stall.
    Plugging in the 12v power adapter yielded the desired result, but I was having problems getting it to read the sd card properly.

    Now, when I try to connect to the serial even with the 12v plugged in, I am having issues.

    It connects, but all I get is a >
    If I type anything (or nothing, it doesn’t matter) and hit enter, the console returns:


    Pressing the reset button makes it spit another > out after a moment, but then has the same behavior.

    If anyone has any insight as to what I am doing wrong, or if I perhaps have a malfunctioning unit, your insight would be appreciated.


    Sounds to me (just guessing here) like you hosed u-boot on the SPI NOR chip. You should be able to place u-boot on an sd-card and boot from it. Once in u-boot on the SDcard you should also be able to re-load u-boot on the SPI NOR (assuming this is the issue). I am not sure if they have this process documented yet, but at least writing u-boot to an SDcard should allow you to boot into an operating system.

    Hope this helps!



    Thanks, I will try that.


    Where might I get the uboot image for this board? I cant seem to find it on the wiki anywhere…


    entering ‘h’ or ‘?’ returns this block of text…

    h/? - print this help screen
    r yyyyyyyy - read register/memory at address yyyyyyyy in hex
    w yyyyyyyy zzzzzzzz - write zzzzzzzz to address yyyyyyyy in hex
    j yyyyyyyy - jump to address yyyyyyyy in hex
    x y - change the boot mode, where y is in hex
    a - UART control passed to AP CPU ROM
    c - UART control passed to CM3 CPU ROM

    Any ideas?…
    I also still have no idea what to do about a messed up U-boot, if that is what is going on… There is no info on the wiki on u-boot, and I am pretty new to anything more complicated than a raspberry pi when it comes to SBCs, so I am pretty used to the lazy “download a .img file and apply it to an sd card.

    I’m pretty confident in my ability to learn, I just need a point in the right direction, maybe a link to some articles explaining how this stuff works. Google has not been helpful at all in that respect.


    Double posting due to lack of edit button… (why?…)

    I managed to find (by reading other threads) that there is an otherwise undocumented ftp site.
    Has many useful files it would seem, including the U-Boot image.
    Now I just need to learn how to flash it.




    thanks for the great information


    This is a slap in the face. I was using OpenWRT and had some hard drive glitches from a power outage, and I did the same as always if power goes out, I was logged into a PuTTY terminal session on OpenWRT, I unmounted the drive and did a drive error scan and fixed all the errors. I did a power reset like always and the device came up without even basic LAN communication. There was nothing working whatsoever other than the green light. I’ve been working for 2 days just to get the terminal interface hooked up. In your specs on Amazon you say 12V *OR* 5V. I did not realize that both power sources must be hooked up for terminal. Never could get putty to communicate on Windows 10 by setting both the driver to 115200 and Putty. I finally downloaded Tera Term and I had no idea if the terminal was working other than with both power sources I received those same weird > arrows and “E”, same as the posters above. By chance I entered a ? and got this:

    h/? – print this help screen
    r yyyyyyyy – read register/memory at address yyyyyyyy in hex
    w yyyyyyyy zzzzzzzz – write zzzzzzzz to address yyyyyyyy in hex
    j yyyyyyyy – jump to address yyyyyyyy in hex
    x y – change the boot mode, where y is in hex
    a – UART control passed to AP CPU ROM
    c – UART control passed to CM3 CPU ROM

    This is insane … what caused it and how to I get my OpenWRT working again?

    I don’t know anything about bootloaders or anything out of the first guide that was published how to install OpewnWRT and then it was just a cookbook for me. Where do I start to get this working again? And while I have your attention, does anyone know why the restart command in OpenWRT will never reboot this device and I have to unplug it every time? What if someone wanted to control the device remotely? …



    Background: Bought this board for OpenWRT use and Samba. Never compiled anything on linux before and just want to utilize the speed and memory of this board. My failure is named above. I am leery that even after I go through all this UART building that it will happen again. So that is a looming concern. Additionally I prefer to work from Windows if possible and even though I can use OpenWRT and can download OPKG sources, I struggle with all else. Now in my research so far:

    Reading from this page: http://wiki.espressobin.net/tiki-index.php?page=Bootloader%2Brecovery%2Bvia%2BUART
    Starting with Windows procedure:
    – Hyperterminal has not been available for perhaps 20 years and was discontinued with Windows XP
    – WTPTP Tools are no longer downloadable; Marvel requires signing up for a user portal and requires a lot of your personal info; then you are informed you must contact Marvel sales and establish a non-disclosure agreement with their team if you have access to anything they provide such as these tools

    Then to attempt Linux procedure:
    – again the WTPTP tools for Linux is not downloadable except in complie-able code. I have enough trouble just signing onto linux much less compiling something so why can’t tools be provided in executable form?

    Looks like I have a boat anchor on my hands and if I get it fixed, how long until it goes belly up again?
    Pretty crazy.


    I tried to contact the office for this company Marvell today an no one answers their phone. I have the additional issue of not knowing if my board would require the 1CS or 2CS firmware because I don’t know what kind of indication shows me how many memory chips I have on my board which is a V5 and with a round sticker “1G”. Id prefer to do a Windows restore attemmpt but the WTPTP executable has been taken down.

    Any idea how to contact this company?


    More comments on this page from someone who is a non Linux professional …
    Reference: http://wiki.espressobin.net/tiki-index.php?page=Bootloader%2Brecovery%2Bvia%2BUART
    In the Linux section, you state that the board can be jumpered for UART but you do not say if we should do it or not or if it is required for this procedure.

    I am trying to get my OpenWRT implementation working again, do I use the latest release to try to build or the ones on the website? I do not have skills to compile any code, sorry.

    In the Linux recovery procedure from the linked material above, you don’t state to start a console to the serial port and what effect this will have if you plan to also use the Wtptp tool to transfer at the same time. I found that Putty would not communicate with this device as I said before. Once I jumpered the board to UART mode, the serial console would not work from any software on Windows or Linux. Is the console supposed to respond with the cryptic E and > if jumpered to UART mode? That isn’t made clear but regardless that “function” is lost on my device with the UART mode jumpered.

    Now without being a programmer, how do I know which files to use to try to recover my OpenWRT image?
    I need to figure out which one of these files is which according to the Linux tool:
    (see my post above for the full help info from this command)
    -B [TIM.bin] Input TIM file (binary)
    -I [Image_h.bin] Input any image file (_h binary)

    Now I have at my disposal:
    (is this my -B or -I option file?)

    I also have from Espressobin zip file “ebin-openwrt-17.10” containing these three files:
    (are either of these my -B or -I option file?

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