Mercury MW150R

This device is NOT RECOMMENDED for future use with OpenWrt due to low flash/ram.
DO NOT BUY DEVICES WITH 4MB FLASH / 32MB RAM if you intend to flash an up-to-date and secure OpenWrt version onto it! See 4/32 warning for details.

1) This device does not have sufficient resources (flash and/or RAM) to provide secure and reliable operation.
This means that even setting a password or changing simple network settings might not be possible any more, rendering the device effectively useless. See OpenWrt on 4/32 devices what you can do now.

2) OpenWrt support for this device has ended in 2022.
19.07.10 was the last official build for 4/32 devices.

  • low-cost router, sold for ~20$ in several flavors, sometimes locally-rebranded.
  • based on the Qualcomm Atheros AR9331 chipset. Thus lot of general information overlaps with the Wiki pages of other AR9331-based devices
  • Some of the flavors can run OpenWrt. Some (from taobao) even have OpenWrt preinstalled.
  • flash ranging from 2MiB to 8MiB. The worst case are the routers that have only 2MiB flash and 8MiB DDR RAM shipped with VxWorks preinstalled. All with at least 4 MB flash can run OpenWrt. If the router you got already runs some linux with 4 megs of flash or more, skip the scary RAM/Flash upgrade part and try the web upgrade.
  • To run properly with all the blows&whistles you may need these patches (at the time of writing not on the trunk):

FIXME: merge this into device database:

CPU Ram Flash Network USB Serial JTag
Atheros AR9331 @ 400 MHz 8-64 MiB 2-16 MiB 4 x 1 Mod Mod No
Model Version OpenWrt Version Supported Model Specific Notes
v8.5/v10.2  Test at your own risk trunk (r28271) Basically same board as TP-Link TL-WR745N similar to TP-Link TL-WR741ND or TP-Link TL-WR703N

This can be VERY rough for newbies. Web update is NOT tested and (likely) will not work if you have a VxWorks one. On the contarary, upgrade via web might work if you have a brick running proper linux.

  • Prereqs:
    • soldering skills
    • smt rework station with hot air gun
    • some coffee
  • This router can have up to 64MiB of RAM making it ideal for running some more services. However, this will require some soldering skills.
  • First, identify how much RAM you have. If you are running on 8MiB RAM, you'll need one 22 Ohm resistor. 0402 is what they usually expect, 0603 also fits nicely.
  • You can get a list of compatible RAM chips from tl-wr703n
  • Once replaced, the router should boot. VxWorks bootloader will ALWAYS detect 8MiB of RAM.

The biggest flash upgrade possible (and tested my me) is 16 Megs. You'll need:

  1. Soldering skills
  2. Some AR9331 router with u-boot. WR703 fits in nicely.
  3. A spare flash chip of 4 8 or 16 megs (some 16 megs will require a diy adapter due to a different footprint.
  4. A linux box with dd, flashrom
  5. A programmer supported by flashrom. I used buspirate
  6. Optional flash adapters for easier connections

So, let's start.

  1. Desolder the flash chip from the mercury and place it into the programmer. I used bus pirate+a diy converter board.
  2. Use flashrom to dump the chip. e.g.
    flashrom -p buspirate_spi:dev=/dev/ttyUSB0 -r factory_2MiB_vxworks.bin
  3. Extract the “art” section from the image. This is 'atheros radio test', with wireless calibration data that is HARDWARE specific. Failing to do so will bring you router to FCC regulators incompliance, or, what is worse - to shitty wireless performance. ART is usually the last 64KiB of the chip, so this will give you a good result:
    dd if=./factory_2MiB_vxworks.bin of=art.bin skip=2031616 bs=1
  4. Now, grab a chip from WR703N (stock firmware will do nicely as well) and dump it as well.
  5. Place the spare chip into the programmer, and do the following.
    1. If you are good with 4MiB - just copy it and proceed to copying the ART section.
    2. Depending on the size of chip create a dummy empty file with dd
      dd if=/dev/zero of=./target.bin count=16384 bs=1024

      for the 16MiB flash. Use count=8192 for 8MiB flash chip.

    3. Copy the bootloader and firmware over it:
      dd if=./wr703ndump.bin of=./target.bin conv=notrunc
    4. Write the ART section over it:
      dd if=./art.bin of=./target.bin conv=notrunc seek=16711680 bs=1
    5. Burn the image to the chip:
      flashrom -p buspirate_spi:dev=/dev/ttyUSB0 -r target.bin
  6. Solder the chip into the router and see if it boots. If it boots, and whatever firmware you put in there started the wireless - then you're lucky. You can not proceed to compiling and setting up OpenWrt as usual

You can grab the layouts of the flash adapters I used (as seen on the photos) at my github repo:

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  • Last modified: 2024/02/12 08:58
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