Saturday, 16 February 2013

Making the WR702n run openwrt part 1

After blindly buying a blue tplink router off eBay at 3am, it turns out I bought the WR702n instead of the openwrt friendly WR703n.

The wr702n runs vxworks and only has 2MB flash and 16MB ram and no USB, This isn't enough for openwrt.
It turns out that other fellow hackers have upgraded the flash and ram on the 703 so I'v done the same to the WR702n.

Getting the Parts...

First port of call is to find suitable flash and ram chips.
I have bought MX25L6445EM2I-10G from china and a 512MB sodimm DDR ram stick to harvest the Hynix HY5DU121622DTP-D43 chips.

Replacing the ram...

Changing the ram first seemed best as vxworks would still run once done..
so out with the Hot air and chip Quik and we now have a 64MB ram chip installed.

 
Ram chip removed with flux and hot air


64MB RAM and serial wires.
Vxworks still booted so ram success fully swapped (first boot too).


The flash chip...

I needed an spi flasher of some kind, I had seen the bus pirate being used but I don't have one and didn't fancy buying anymore tools if I dint need to.

Arduino mini pro (3.3v) with spi chip attached to wires. Full size arduino used just for usb to serial.
After spotting  a post on hack a day using an arduino to program the chips, I installed Ubuntu and programmed serprog onto an arduino mini pro. It took a bit of fiddling to get it recognized by flashrom but after a few port speed issues I was able to dump the contents of the new chip.

DAS U-boot...
Now with it all ready to go I needed to find a copy of uboot to install. turns out there's an awesome version with an http server built in for flashing.

Wrote that to the chip with flashrom, verified it and then soldered it in place of the 2MB chip.

Success!!!

powered it up and uboot started to scroll messages in putty. Next was to get openwrt installed.
Turns out the http server is a bit temperamental and only likes firefox 13.0.1? 

after programming the latest sysupgrade file for openwrt it flashed itself and rebooted and was greeted by the boot log of openwrt :)

To be continued...

I still need to recover the unique "ART" partition from the original 2MB flash chip so the wifi will work.

I also need to update uboot for 8mb as it only can access the first 4mb atm. 

Lastly the usb port needs to work so I just need to add some components to get that working too.


2 comments:

  1. That's awesome that you took this on. I have one of these after making the same slip on purchasing the 702. Any further updates on running open-wrt?

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  2. Nice job, I will be performing the same mod on a wr720n(the version without built in power adapter).
    Ref saving and transfering the art partition check out the intructions at http://wiki.openwrt.org/toh/mercury/mw150r
    They seem pretty straight forward and I should be able to follow them once the parts come in.
    Thanks for pointing me in the right direction.

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