Sunday 15 March 2015

Mini 3G 150M A5-V11 Router (internals/UART)

This is a generic/unbranded router from dealextreme (product 217078)


There's very little information in the product description, but for my 7 quid I ended up with a board known as "A5-V11", which has a RT5350, 4M SPI flash, 32M RAM. It is supported by openwrt (here) but the current bleeding edge with the defaults set is too big. It fits if you drop the IPv6 related packages.

It's already well documented so there isn't any need for much more here. Worth noting is that a standard SOIC clip (i.e. Pomona-style) won't quite make contact due to the position of the big capacitor in the middle. The micro USB port is only used for power... so for future experiments I wired the UART to it following the same pinout as Mediatek stuff. A resistor is required on RX or it won't boot (value not critical, also works fine with 330 ohm).

Maybe needs a couple of blobs of hot glue

The jffs2 thing is a known bug

10 comments:

  1. Is there an OpenWRT build that allows me to plug in a USB sound module into this device and somehow emulate like the USB sound module was plugged into my windows machine? In other words, I want to play music over the LAN cable from my Windows PC to my stereo system in another part of the house. Thanks!

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    1. Honestly - I've no idea. If there is, you'll struggle to fit it in the available free space though. OpenWRT forums are probably a good place to ask: https://forum.openwrt.org/

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  2. You wouldn't be an active participant in the ROOter group would you?

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    1. Nope, sorry. I've actually not done anything more with this router since I originally wrote this post.

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  3. OK, thanks. I like your blog, lots of diverse topics.

    Note: For this device, a good OpenWRT build is found at http://ofmodemsandmen.com/downloadsp.html which supports many modems.

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  4. Could it be, that Rx and Tx need to be swapped on the USB side?

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    1. Sure - there are hundreds of different USB-UART cables, I'm sure some are labelled the opposite way around. My annotated photo shows the direction relative to the SoC, as in "TX" is the router transmitting data out, so should be connected to "RX" of a correctly labelled UART.

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    2. Hmm, I think I know why Rx and Tx is swapped on my cable. I own the same cable like the one you modded in this post: http://www.stevenhoneyman.co.uk/2014/11/mtk-mediatek-debug-cable.html. You mentioned there, that you soldered the green and white cables the wrong way round (I assume you swapped them aferwards), but on my unmodded cable these are exactly the same order like in the picture of your post.


      This UART interface is pretty useful! In the end I was able to unbrick my router :) So thank you for this blog post!

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    3. Hey,
      I managed to run Debian Jessie on this router :D
      Just in case you are interrested:
      https://www.youtube.com/watch?v=pZLU15zx1EU

      The GUI is pretty slow, but there are some useful cli programms you can use with from debian!

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  5. Hey :)
    I created a portable wireless music system with webradio, dlna/upnp server and dlna/upnp renderer with this little router!
    All in all this project costs about 25€.
    Read more:
    http://board.nwrk.biz/viewtopic.php?id=125

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