The device is a wireless N router with

• 2 detachable antennas
• 4 Port 100/10 Switch
• 1 Port 100/10 Wan Interface
• 4 MB Flash

Note1: The TL-WR841N is identical except that the antennas are not detachable. TP-Link naming scheme is, that devices ending in a D have detachable antennas.
Note2: v5.4, v5.2 etc. are all v5. The only difference is the firmware version the come with. TP-Link naming scheme is, that numbers behing the comma, refer to changes in the firmware only, the hardware is identical.

(One author review)I have only tried Backfire (10.03) on it, works quite well. It can be installed either via the standard TP-Link web interface (OEM install) or over TFTP using a serial console.

(Another author review)10.03.1rc4 has many wireless driver changes and it's more stable than 10.03. PPPoE seems to work fine.

Flash of TP-Link TL-MR 3420 is coming to WR841ND v7.2 - verified. But working USB port has not been verified. Probably enough to use this firmware, but do not compile a new one:)

1. Download V5 image: http://downloads.openwrt.org/attitude_adjustment/12.09/ar71xx/generic/openwrt-ar71xx-generic-tl-wr841nd-v5-squashfs-factory.bin
2. Log in to router web interface and select the firmware image you just uploaded as an update
3. Sit and wait while it flashes. It will reboot and be accessible at 192.168.1.1.

1. Download V7 image: http://downloads.openwrt.org/attitude_adjustment/12.09/ar71xx/generic/openwrt-ar71xx-generic-tl-wr841nd-v7-squashfs-factory.bin
2. Log in to router web interface and select the firmware image you just uploaded as an update
3. Sit and wait while it flashes. It will reboot and be accessible at 192.168.1.1.

Warning! in some cases after reboot you don't have web interface (GUI), only telnet and ssh access. You can install GUI, for details see: luci.essentials, but before install LuCI (GUI) you need to configure your router to have access to internet, for configuration see: internet.connection

1. Download V8 image from: http://downloads.openwrt.org/attitude_adjustment/12.09/ar71xx/generic/openwrt-ar71xx-generic-tl-wr841n-v8-squashfs-factory.bin
2. Log in to router web interface http://192.168.0.1/ and select the firmware image you just uploaded as an update
3. Sit and wait while it flashes. It will reboot and be accessible at 192.168.1.1.

Warning! in some cases after reboot you don't have web interface (GUI), only telnet and ssh access. You can install GUI, for details see: luci.essentials, but before install LuCI (GUI) you need to configure your router to have access to internet, for configuration see: internet.connection

Beware that this installation method needs a TTL level serial console and a working TFTP server and should not be attempted unless you have experience with this sort of thing or are eager to learn :)

This is taken more or less verbatim from https://forum.openwrt.org/viewtopic.php?id=24203, thanks to dl3daz.

1. Download http://downloads.openwrt.org/backfire/10.03/ar71xx/openwrt-ar71xx-tl-wr841nd-v5-squashfs-factory.bin to your TFTP server.
2. Hook your routers WAN ethernet port up to your network
3. Hook up the serial console as explained in the section "serial console" and do the "tpl" trick to get console access
4. Now we need to set router and server IP addresses (here named ROUTERIP and SERVERIP, substitute these with the real IP addresses). Type in the console:

   setenv ipaddr ROUTERIP
   setenv serverip SERVERIP
   printenv
   

5. Double check that the output of printenv lists the IP addresses you just set. Now we can load the firmware over TFTP with "tftpboot 0x80000000 openwrt-ar71xx-tl-wr841nd-v5-squashfs-factory.bin":

   ar7240> tftpboot 0x80000000 openwrt-ar71xx-tl-wr841nd-v5-squashfs-factory.bin
   Using eth0 device
   TFTP from server 192.168.32.253; our IP address is 192.168.32.246
   Filename 'openwrt-ar71xx-tl-wr841nd-v5-squashfs-factory.bin'.
   Load address: 0x80000000
   Loading: checksum bad
   #################################################################
            #################################################################
            #################################################################
            #################################################################
            #################################################################
            #################################################################
            #################################################################
            #################################################################
            #################################################################
            #################################################################
            #################################################################
            ######################################################
   done
   Bytes transferred = 3932160 (3c0000 hex)
   

6. Note the "3c0000" in the last line (your number may differ). Now execute the following commands, if necessary replacing 3c0000 with the number you got from tftpboot

For TL-WR841ND v3:

ar7100> erase 0xbf020000 +0x3c0000
                                                                             
First 0x2 last 0x3d sector size 0x10000                                      
  61                                                                         
Erased 60 sectors
ar7100> cp.b 0x80000000 0xbf020000 0x3c0000                                  
Copy to Flash... write addr: bf020000                       
done                                                        
ar7100> reset                                               
                                                            
Resetting...

For TL-WR841ND v5:

ar7240> erase 0x9f020000 +0x3c0000
...
ar7240> cp.b 0x80000000 0x9f020000 0x3c0000
ar7240> bootm 0x9f020000

1. You're set, OpenWrt should now boot and you can set it up as usual:

   U-Boot 1.1.4 (Apr  9 2009 - 12:29:57)

• Download the original firmware from TP-Link's site (IMPORTANT: Download a firmware which has does not contain the word boot in it's filename (such as wr741nv1_en_3_9_18_up_boot(100104).bin), extract the file and rename it to something short and simple such as tplink.bin.
• Upload it to /tmp-directory on your router and execute:

  mtd -r write /tmp/tplink.bin firmware
  

• Be careful, if you were hit by the "missing web interface" problem described above, you will be probably see the same issue when flashing back to OEM and the box will lack in telnet or ssh, too, so no way to get out without hardware intervention.

generic.failsafe

1. When the SYS led (under gear icon) starts to blink push the QSS button for around 5-10 sec. Now the led should blink a lot faster than before.

V 7.2 July 2012

1. Disconnect the router from the internet, connect it with a PC via RJ45 cable and perform a 30/30/30 restart
2. Change the ip on the PC to 192.168.1.2, subnet mask must be 255.255.255.0 and restart the router by unplugging the power cable
3. Perform a failsafe boot, quickly use

   telnet 192.168.1.1

If this didnt work check the ip adress on the PC or if you were too slow to connect during the failsafe mode. Still not working? Read this!

In telnet do the following things one after another:

• Define a password

  passwd

  enter

  yourpassword

  enter

  againyourpassword

  enter

• Kill the broken OWRT firmware

  mtd -r erase rootfs_data

  enter

  firstboot

  enter

  reboot -f

  After rebooting log in again just to check if the router is accessable. If you cant start again at the beginning.

Now change the network settings on the PC back to "Aquire IP adress automatically" and connect the router with the internet. Do a manual reboot by simply turning it off and back on again. The PC should now get an ip adress by DHCP. If this is the case you successfully resetted the router. If not repeat from the beginning or do this if you like.

Basically the router now works like after the initial flash to OWRT. Now you have to configure the internet connection and probably you want to install LUCI. After that open your browser, connect to 192.168.1.1 and log in with the data you entered via telnet.

V8.X note

Debricking see the above, but you will have to plug your cable to WAN port in failsafe to be able to telnet 192.168.1.1.

configuration

Read this howto to use buttons on TP-Link

Found in WR741ND wiki page and coppied. It works on WR841ND too.

(Thanks to obsy) Wifi toggle by QSS button Simply create a new file called 01onoff in /etc/hotplug.d/button/

vi /etc/hotplug.d/button/01onoff

and copy these lines inside (remember to push 'i' for insert)

#!/bin/sh

[ "$BUTTON" = "wps" ] && [ "$ACTION" = "pressed" ] && {
 SW=$(uci get wireless.@wifi-device[0].disabled)
 [ $SW == '0' ] && uci set wireless.@wifi-device[0].disabled=1
 [ $SW == '0' ] || uci set wireless.@wifi-device[0].disabled=0
 wifi
}

Save and exit

(esc :wq)

Getting serial console is pretty standard fare. You need a MAX323 or similar level-shifter. The pinout on the router is RX - TX - GND - +5V (Power connector).

If you do not have serial port on your PC, use Nokia CA-42 data USB cable.

For TP-LINK WR841ND V7.2 power conector (+5V) is ignored, just connect RX - TX - GND and router power cord, work fine…

Another user notes: My TP-LINK WR841ND V7.2 has a VCC of +3.3V and like the TL-MR3420 http://wiki.openwrt.org/toh/tp-link/tl-mr3420#serial needed to connect a 10k pullup resistor between the TX and the 3.3V pin to get reliable serial.

Yet another user notes: My TP-Link WR841ND V7.1 also requires the 10k pullup resistor between TX and the 3.3V pin. Without the resistor I just get garbage when I type, but can see some console output.

Version	v3.2	v5	v7.X
Image
U-Boot speed	9600	115200
kernel speed	115200 - switch automaticaly	115200
Data format	always 8N1

After connecting, you will be greeted by something like this:

AP93 (ar7240) U-boot
DRAM:  
sri
#### TAP VALUE 1 = 9, 2 = 9
32 MB
id read 0x100000ff
flash size 4194304, sector count = 64
Flash:  4 MB
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   ag7240_enet_initialize...
No valid address in Flash. Using fixed address
: cfg1 0xf cfg2 0x7014
eth0: 00:03:7f:09:0b:ad
eth0 up
No valid address in Flash. Using fixed address
: cfg1 0xf cfg2 0x7214
eth1: 00:03:7f:09:0b:ad
ATHRS26: resetting s26
ATHRS26: s26 reset done
eth1 up
eth0, eth1
Autobooting in 1 seconds

This violates regulatory requirements

Edit the file /etc/config/wireless

1. Below config 'wifi-device' 'radio0' add

   option 'noscan' '1'
   

2. option 'htmode' should be set either to HT40+ or HT40-(HT40+ wont work with Channel 11)

   option 'htmode' 'HT40+'
   

3. Restart wireless

   wifi

check whether eth0/eth1 are switched!

Tested on WR841n_v5.1

Attention. Firmware of TP-Link TL-MR 3420 is coming to WR841ND v7.2 - verified. (OpenWrt Firmware Attitude Adjustment (r28380) / LuCI Trunk (trunk+svn7612)) But working usb port has not been verified. Probably enough to use this firmware, but do not compile a new one :)

Overview of the board:

Soldering (wire with red accent means D+). R185 and R183 can be shorted then D+/D- will appear in J1.

To get working USB the new firmware build is required. Files to edit are listed below:

1. Edit file target/linux/ar71xx/files/arch/mips/ar71xx/mach-tl-wr841nd.c

    Add line #include "dev-usb.h" after line #include "dev-leds-gpio.h"
    Add line ar71xx_add_device_usb(); before line ar71xx_add_device_mdio(0x0);

2. Edit file target/linux/ar71xx/files/arch/mips/ar71xx/setup.c

   Add line ar71xx_pll_wr(0x08, 0x00001030); before line ar71xx_detect_mem_size();

3. Edit file target/linux/ar71xx/files/arch/mips/ar71xx/Kconfig:

config AR71XX_MACH_TL_WR841N_V1
        bool "TP-LINK TL-WR841N v1 support"
        select AR71XX_DEV_M25P80
        select AR71XX_DEV_PB42_PCI if PCI
        select AR71XX_DEV_DSA
        select AR71XX_DEV_GPIO_BUTTONS
        select AR71XX_DEV_LEDS_GPIO
        select AR71XX_DEV_USB
        default n

For newer version of trunk (as of 2013 March) 1.Edit file target/linux/ar71xx/files/arch/mips/ath79/mach-tl-wr841n.c

    Add line #include "dev-usb.h" after line #include "dev-leds-gpio.h"
    Add line ath79_register_usb(); after line ath79_register_eth(0);

2. Edit file target/linux/ar71xx/generic/profiles/tp-link.mk, add packages in the definition of TLWR841 as following.

define Profile/TLWR841
	NAME:=TP-LINK TL-WR841N/ND
	PACKAGES:=kmod-usb-core kmod-usb2 kmod-ledtrig-usbdev
endef

i.e L7805 with 470uF and 100uF can be used to obtain 5V from the stock power supply.

NOTE: in case of v5.1 sections for WR741N instead of WR841N_V1 have to be edited (Kconfig, mach-tl-wr741nd.c).

tested with WR841 v7.1 and trunk revision 30430. New patch for rev. 32461 available

Hardware mod is on pictures, nothing changed.

Kernel mod is different, because new kernel version is released in revision 30430.

Here is patch for kernel 3.3: http://mysicka.ics.muni.cz/openwrt/usb-patch-final.patch

Apply this patch and build…

https://forum.openwrt.org/viewtopic.php?id=37010

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