Sunday, December 15, 2013

Building OpenWRT for MobileLite Wireless

I have always had a fondness for OpenWRT, and I know it suports our MT7620 as a target, so why not give it a shot. I have already cheated a little bit and built a test image with root fs on ramdisk that I loaded directly from the uBoot menu.

Seems that I forgot to write while playing today, so here we have a short summary. After playing with OpenWRT, and making a port for the MLW221, I decided to get ethernet up and running. So after reading a bit of documentation I found the pinout for ethernet.

P5 = Tx-
P6 = Tx+
P7 = Rx-
P8 = Rx+

I found an old router and lifted the pins on the filter, and after a little bit of soldering we have ethernet on our device. This is not a permanent solution, since there is no room for the ethernet connector inside the device. If I have to bring a dongle with me, it might just as well be en USB-ethernet dongle.

But the end result is that we can select to boot from tftp in the uBoot menu, so now it will take a few seconds to transfer the test image, instead of 10 minutes. We are moving forward here.

My alternative ethernet port setup.


  1. Hi is there any way i can change my MAC address on my MLW221

  2. In OpenWrt I guess you could just set it in the wifi script ( I'm sure it's just some minor changes that are needed to be able to change it from the uci web interface. In stock firmware it seems like it's loading the MAC address from the NVRAM partition (from looking at the boot log). If that is the case, you could use the nvram utility to change the settings. If that doesn't work you could change the partition directly from u-boot.

  3. Can I solder a cabel directly to the pins and then connect to the pc? If yes, which pins on the mlw221 go to which pin on the cabel? TX+ to RX+ and TX- to RX- and vice versa? Or is it a different setup? Thank you very much!

    1. I can't remember to much from this device, but the documentation specifies builtin phy. The programmers guide for MT7620 shows how to control it. But I can't remember which port the pins connect to. The block diagram shows that some of the ports are connected to a builtin phy. I assume I had some good reason to use the hardware I did at the time, so my general recommendation would be not to connect it directly.

      But if you do so anyways, I would at least just connect to some cheap USB Ethernet dongle or some other device that is cheap to replace.