TP-Link TL-WR941ND

  • Unpopulated serial and USB headers

Clones

Known clone of this device: Mercury MWR300T+.

Supported Versions

Version/Model S/N OpenWrt Version Supported Model Specific Notes
v1 - Backfire 10.03 N/A
v2 - Backfire 10.03 Similar to v1
v3.x - Backfire 10.03.1 Similar to v2
v3.8 - Attitude Adjustment (12.09 final) Same as v3, BUT DIFFERENT FLASH CHIP, Backfire will BRICK! see topic
v4 - Backfire 10.03 Similar to tl-wr741nd
v5.0 - Attitude Adjustment (12.09 final) Similar to tl-wr841nd v8, see OpenWrt forum post
v5.1 - Attitude Adjustment (12.09 final) Similar to tl-wr841nd v8, see OpenWrt forum post and OpenWrt forum post
v6 - trunk Similar to tl-wdr3500

WARNING:!: (2013-08-04): ATTITUDE ADJUSTMENT 12.09 Final r36088 still works, but BARRIER BREAKER Bleeding Edge r37660 has a problem where it thinks the failsafe button is always pressed (on a v3.x) Unless if you know how to make a serial console and do TFTP, best to stay away from trunk for a while. Internet search hints this may be true for more TP-Link models.

Hardware Highlights

Version CPU Ram Flash Network USB Serial JTag
v1 AR9132@400MHz 32MB 8MB 4x1 No Yes N/A
v2 AR9132@400MHz 32MB 4MB 4x1 No Yes N/A
v3 AR9132@400MHz 32MB 4MB 4x1 No Yes N/A
v4 AR7240@400MHz 32MB 4MB 4x1 No Yes N/A
v5.0 AR9341@535MHz 32MB 4MB 4x1 No Yes N/A
v5.1 AR9341@535MHz 32MB 4MB 4x1 No Yes N/A
v6 AR9344@560MHz 64MB 4MB 4x1 No Yes N/A

Note: The above spec for v5.0 and v5.1 is valid only if the FCC ID of your device is TE7WR941NXV5. If the FCC ID of your device is not TE7WR941NXV5 but the hardware version is v5.x, then the above spec doesn't apply to your device and you should proceed with caution.

Installation

OpenWrt firmware can be flahsed via the OEM WebInterface.

  • You could log in to the OEM firmware as root using 5up as password.
  • You can get into U-Boot typing tpl at the 1s pause at the beginning of the boot process.

OEM easy installation

These instructions use as example a v3 model, browse the trunk snapshot repository for the binary that matches your hardware version. Pay also attention that we can find for each model version two similar files, one the -factory and the other one -sysupgrade, on this section we will use the -factory one.

  1. Download the firmware binary from here.
  2. Login to the default WebGUI and flash the router.
  3. Wait for the router to reboot, SYS LED will stop flashing and become static.
  4. Telnet to 192.168.1.1, set a root password and enjoy.

Upgrading OpenWrt

If you have already installed OpenWrt and like to reflash for e.g. upgrading to a new OpenWrt version you can upgrade using the console/terminal. It is important that you put the firmware image into the ramdisk (/tmp) before you start flashing otherwise crazy things can happen.

We will use the -sysupgrade firmware file, for more information about this read the OEM Easy Installation section. To start the upgrade process login to your router using SSH and make sure you've Internet access in order to download the new firmware file.

# cd /tmp
# wget http://downloads.openwrt.org/snapshots/trunk/ar71xx/openwrt-ar71xx-generic-tl-wr941nd-v3-squashfs-sysupgrade.bin
# sysupgrade -v /tmp/openwrt-ar71xx-generic-tl-wr941nd-v3-squashfs-sysupgrade.bin

Flashing via UBoot

Warning!
This section describes actions that might damage your device or firmware. Proceed with care!

A 3.3v TTL serial connection is required ! (Forum post) Do not try this method unless you're really sure what you're doing.

During UBOOT "1-second" message, quickly key sequence: tpl to stop UBOOT from loading the kernel and go into uboot mode proper.

ar7100> setenv serverip 192.168.1.254; setenv ipaddr 192.168.1.1
ar7100> tftp 0x80800000 openwrt-ar71xx-tl-wr941ndv2-squashfs.sysupgrade.bin
ar7100> erase.b 0xbf020000 +0x3c0000
ar7100> cp.b 0x80800000 0xbf020000 0x3c0000
ar7100> reset

Note #1: 0x3c0000 is the size of the firmware, be aware that you may have a different size thus bricking your router.

Note #2: 0xbf020000 is the from addr, for your device version you can get it by issuing the command: "printenv bootcmd", not doing so will turn your router into a brick.

Revert to original firmware

Warning!
This section describes actions that might damage your device or firmware. Proceed with care!

You can download the original firmware from the TP-LINK support section and flash it without modification.

Only perform the dd action below if your original firmware has the word "boot" in it, for example, "wr941nv4_en_3_9_17_up_boot(091118).bin". DO NOT dd your original firmware if it has no "boot" in its name, for example, "wr941nv4_en_3_11_5_up(100427).bin", because if you do, you will brick your router ! This was confirmed by supertom64 in wr1043nd.
Cut first 0x20200 bytes from original firmware containing boot in the filename:

dd if=orig.bin of=tplink_boot.bin skip=257 bs=512

Flash via uboot or mtd, you cannot flash via WebGUI otherwise you will turn your router into brick.

First you need to get the firmware file onto your box. If you are able to connect to your OpenWrt console and you have your network configured properly, you can use wget or scp to copy the firmware binary into the /tmp folder.

To start flashing via mtd you have to call (wr.bin is the file containing the firmware you previously downloaded):

root@OpenWrt:/tmp# mtd -r write wr.bin firmware
Unlocking firmware ...

Writing from wr.bin to firmware ...
Rebooting ...
Terminated

Failsafe mode

generic.failsafe

  • While the SYS LED is on immediately press the QSS button.
  • If done right the SYS LED will start flashing very quickly.

Hardware

Info

Instruction set: MIPS
Vendor: Atheros
Bootloader: uboot
System-On-Chip: AP81
CPU Speed: 400 Mhz
Flash-Chip: S25FL032P (HW Ver 3.6)
Flash size: 4 MiB
RAM: 32 MiB
Wireless: Atheros AR9103 802.11n
Ethernet: Switch part of SoC
USB: No, but USB port header has been discovered on the board
Serial: Yes
JTAG: N/A

Photos

TODO.

Opening the case

Note: This will void your warranty! These instructions are not very good! (yet…)

  1. There are two screws underneath the rubber feet at the back (were the RJ45 jacks are) of the device. Remove those.
  2. Remove the front plastic piece.
  3. Try to open the white plastic cover at the top only a little bit.
  4. Unhinge the plastic cover at the front.

There is also an easy way to do it

  1. Remove those two screws underneath the rubber feet at the back
  2. Get your nails in the grooves underneath the router and lift the panel
  3. Use your nails and slowly go around the case to Unhinge the plastic cover at the front

Main PCB (not V3.2)

serial pin ver: 5.1

Serial

Look at the PCB picture. Serial port is located were the 4 wires are soldered to the board. The left one (green) is soldered to the pad labeled "P1".
Pinout of the port is : |TX|RX|GND|VCC(3.3)| (direction as seen in PCB picture below; Pad "P1" is TX)
Before you can use the serial port you have to bridge R356. (A smd pad right underneath the serial port pad "P1").

It is not possible to directly connect the serial port to one of your computer (voltage mismatch). You have to use a converter (i.e. a Nokia CA-42 cable, serial to USB converter or something similar. An Arduino MEGA with a simple serial bridge also works).

On the ver3 board, there is a 4.7k pull-down resistor on the RX pin. To interface with 5V devices (such as the Arduino MEGA), use a 2k2 resistor in series with the RX pin (Arduino's TX pin). Arduino's RX pin can be connected directly with the router's TX pin.

PCB WR941ND Ver: 3

PCB WR941ND Ver: 6

Once the original firmware has booted up completely, you can press return to activate the Linux login prompt.

The password to get a root Shell access is 5up:

TL-WR941N mips #32 Wed Oct 17 18:08:12 PDT 2012
TL-WR941N login: root
password: 5up

JTAG

TODO

Specific configuration

VLAN Config

Setting up VLAN is a bit different from other devices:

First, you have to edit /etc/rc.local (sample config for VLAN 100 and 200 on trunk port lan4): # Put your custom commands here that should be executed once # the system init finished. By default this file does nothing. vconfig add lan4 100 vconfig add lan4 200 ifconfig lan4.100 up ifconfig lan4.200 up exit 0

Then, you have to edit /etc/config/network and reboot the device (that /etc/rc.local is executed): config interface vlan100 option ifname "lan1 lan2 lan3 lan4.100" #[…] config interface vlan200 option ifname "lan4.200"

Buttons

The device has 2 buttons:

  • the reset button at the back
  • the "QSS" labeled button at the front

Basic configuration

Since this part is identical for all devices, see Basic configuration.

Connect stuff to the USB port

If you have an USB port, please see Connect stuff to the USB port.

Hardware mods

USB

Tags

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toh/tp-link/tl-wr941nd.txt · Last modified: 2014/08/23 00:47 by vedant