The TP-Link WR740N is an even lower-cost (around 20€/$20 retail in 10/2012) variant of the TP-Link WR741ND differing only in the non-removable antenna.
Since the hardware in WR740N is similar to WR741N, most of the contents in TP-Link WR741ND applies to this router too.
|Model Version||OpenWrt Version Supported||Model Specific Notes|
|v1 (China)||if you don't modify hardware Not supported||BCM5356 SOC 2MB Flash/8MB RAM|
|v2 (China)||if you don't modify hardware Not supported||BCM5356 SOC 2MB Flash/8MB RAM|
|v1.1||10.3.1RC6(r27841) trunk (r24811)||8455 Gargoyle 1.5.1|
|v2.4||trunk (r28314)||Rounded chassis, 350mhz cpu|
|v3||trunk (r28269)||Rounded chassis|
|v4||trunk (r29631), see this ticket||AR9330 400Mhz CPU 4 or 2MB Flash/32MB RAM|
|v4.23||Attitude Adjustment 12.09-beta (trunk r33312)||SoC: Atheros AR9330 rev 1, 400Mhz CPU, 4MB Flash/32MB RAM|
|v4.24||Attitude Adjustment 12.09||SoC: Atheros AR9330 rev 1, 400Mhz CPU, 4MB Flash/32MB RAM|
|v5 (China)||likely unsupportable. WiP||AR9331 SOC 2MB Flash/16MB RAM|
- Sometime around August 2011 (v4), TP-Link began to use 16MB RAM / 2MB flash for the Chinese versions of many of their devices. International versions retain the 32MB RAM / 4MB flash.
- International versions v4.2 and v4.3 work without apparent problems from trunk r29631 onward.
- International version v4.23 works without apparent problems from trunk r33312 (Attitude Adjustment 12.09-beta) onward.
- International version v4.24 works without apparent problems with Attitude Adjustment 12.09.
Your model version can be identified from the label: see this page for details.
|Broadcom BCM5356@333MHz||8MiB||2MiB||4 x 1||?||Mod||?|
|Atheros AR7240@400MHz||32MiB||4MiB||4 x 1||mod||Yes||No|
|Atheros AR9330 rev 1@400MHz||32MiB||4MiB||4 x 1||mod||Yes||?|
- Atheros AR9285 wireless chip
Please check out the article Flash Layout for explanations.
Note: Below is the kernel log from the unmodified Attitude Adjustment (12.09-beta) generic WR740N v4 image firmware, showing the Flash Layout of the WR740N v4.23
[ 0.660000] 5 tp-link partitions found on MTD device spi0.0 [ 0.660000] Creating 5 MTD partitions on "spi0.0": [ 0.670000] 0x000000000000-0x000000020000 : "u-boot" [ 0.680000] 0x000000020000-0x000000108468 : "kernel" [ 0.690000] 0x000000108468-0x0000003f0000 : "rootfs" [ 0.720000] mtd: partition "rootfs_data" created automatically, ofs=2D0000, len=120000 [ 0.720000] 0x0000002d0000-0x0000003f0000 : "rootfs_data" [ 0.730000] 0x0000003f0000-0x000000400000 : "art" [ 0.740000] 0x000000020000-0x0000003f0000 : "firmware"
- The trunk WR740n hardware v1 image works unmodified and it can be flashed through the stock TP-Link web interface (another file exists for version 3). The v1 file was also successfully tested on hardware version 2.5.
- Hardware version 4.23 works perfectly with the unmodified Attitude Adjustment (12.09-beta) generic WR740N v4 image. The best installation method is flashing it through the stock TP-Link web interface.
- Hardware version 4.24 works perfectly with the unmodified Attitude Adjustment (12.09) generic WR740N v4 image. The best installation method is flashing it through the stock TP-Link web interface.
Managed to squeeze IPv6 packages (radvd, dhcp6 server and client) along with Luci web interface with english and romanian support into the 4 MB firmware ONLY for TP-LINK WR740N version 2.4 and 3. Along with the above packages config files also the kernel was stripped down for the exact WR740N hardware via buildroot "make kernel_menuconfig". Tested on romanian biggest ISP provider (RCS-RDS) for the IPv6 fiberlink services. http://www.ip6.ro/firmware (page is in romanian only so far..)
These were prepared using Attitude Adjustment 12.09-beta ImageBuilder (r33312). Since HW version v4.23 or v4.24 doesn't have any stock USB, any USB stuff was removed from the firmware. Added functionalities include:
- QOS (incl. LuCI support)
- OpenVPN (incl. LuCI support)
- Tinyproxy (incl. LuCI support)
- UPNP (incl. LuCI support)
The command line used for the preparation was (all are the default packages, only these are changed: -kmod-ledtrig-usbdev -kmod-usb-core -kmod-usb-ohci -kmod-usb2 luci-app-qos luci-app-openvpn luci-app-tinyproxy luci-app-upnp):
make image PROFILE=TLWR740 PACKAGES="base-files busybox dnsmasq dropbear firewall hotplug2 iptables iw jshn kernel kmod-ath kmod-ath9k kmod-ath9k-common kmod-cfg80211 kmod-crypto-aes kmod-crypto-arc4 kmod-crypto-core kmod-gpio-button-hotplug kmod-ipt-conntrack kmod-ipt-core kmod-ipt-nat kmod-ipt-nathelper kmod-leds-gpio kmod-ledtrig-default-on kmod-ledtrig-netdev kmod-ledtrig-timer -kmod-ledtrig-usbdev kmod-lib-crc-ccitt kmod-mac80211 kmod-nls-base kmod-ppp kmod-pppoe kmod-pppox -kmod-usb-core -kmod-usb-ohci -kmod-usb2 kmod-wdt-ath79 libblobmsg-json libc libgcc libip4tc libiwinfo libiwinfo-lua libjson liblua libnl-tiny libubox libubus libubus-lua libuci libuci-lua libxtables lua luci luci-app-firewall luci-i18n-english luci-lib-core luci-lib-ipkg luci-lib-lmo luci-lib-nixio luci-lib-sys luci-lib-web luci-mod-admin-core luci-mod-admin-full luci-proto-core luci-proto-ppp luci-sgi-cgi luci-theme-base luci-theme-openwrt mtd netifd opkg ppp ppp-mod-pppoe swconfig uboot-envtools ubus ubusd uci uhttpd wireless-tools wpad-mini luci-app-qos luci-app-openvpn luci-app-tinyproxy luci-app-upnp"Notes:
- The proposed altered openwrt-ar71xx-generic-tl-wr740n-v4-squashfs-factory.bin firmware have not been tested, so you'd better first use the default Attitude Adjustment (12.09-beta) generic WR740N v4 image (r33312) to flash your brand new router and then use the proposed altered openwrt-ar71xx-generic-tl-wr740n-v4-squashfs-sysupgrade.bin that has been tested and working on my two WR740N v4.23 routers.
- The proposed altered openwrt-ar71xx-generic-tl-wr740n-v4-squashfs-sysupgrade.bin that has been tested and working with no problems on my two WR740N v4.23 routers.
- The space used by the modified firmware is as follows:
root@OpenWrt:~# df Filesystem 1K-blocks Used Available Use% Mounted on rootfs 320 240 80 75% / /dev/root 2816 2816 0 100% /rom tmpfs 14672 80 14592 1% /tmp tmpfs 512 0 512 0% /dev /dev/mtdblock3 320 240 80 75% /overlay overlayfs:/overlay 320 240 80 75% /You can download the proposed 12.09-beta firmware from here.
You can download the proposed 12.09 Final firmware from here. Since the luci-app-openvpn package is broken in 12.09 Final + wireless-tools is not used anymore this is the command line used for the preparation of the altered 12.09 Final firmware image:
make image PROFILE=TLWR740 PACKAGES="base-files busybox dnsmasq dropbear firewall hotplug2 iptables iw jshn kernel kmod-ath kmod-ath9k kmod-ath9k-common kmod-cfg80211 kmod-crypto-aes kmod-crypto-arc4 kmod-crypto-core kmod-gpio-button-hotplug kmod-ipt-conntrack kmod-ipt-core kmod-ipt-nat kmod-ipt-nathelper kmod-leds-gpio kmod-ledtrig-default-on kmod-ledtrig-netdev kmod-ledtrig-timer -kmod-ledtrig-usbdev kmod-lib-crc-ccitt kmod-mac80211 kmod-nls-base kmod-ppp kmod-pppoe kmod-pppox -kmod-usb-core -kmod-usb-ohci -kmod-usb2 kmod-wdt-ath79 libblobmsg-json libc libgcc libip4tc libiwinfo libiwinfo-lua libjson liblua libnl-tiny libubox libubus libubus-lua libuci libuci-lua libxtables lua luci luci-app-firewall luci-i18n-english luci-lib-core luci-lib-ipkg luci-lib-nixio luci-lib-sys luci-lib-web luci-mod-admin-core luci-mod-admin-full luci-proto-core luci-proto-ppp luci-sgi-cgi luci-theme-base luci-theme-openwrt mtd netifd opkg ppp ppp-mod-pppoe swconfig uboot-envtools ubus ubusd uci uhttpd wpad-mini luci-app-qos luci-app-tinyproxy luci-app-upnp openvpn"
- Everything said for v4.23 is applicable for v4.24 too (tested by user christoforos, did not cracked open the case though).
Note: Please reset your router to factory defaults if it has been previously configured/used.
- Power up your router device.
- Connect the local PC to anyof the LAN ports of the Router.
- Choose the menu “System Tools → Firmware Upgrade”.
- Upload the openwrt-ar71xx-generic-tl-wr740n-vXXX-squashfs-factory.bin file to router. vXXX is the version that is known to work with your router (like for HW rev4.23 vXXX is actually v4). Be sure to chose a …….-squashfs-factory.bin file!
- Wait for the router to reboot.
- Telnet to 192.168.1.1 and set a root password, or browse to http://192.168.1.1 if LuCI is installed.
Flashing using TFTP works with the steps descibed in TP-Link WR741ND TFTP Installation (it needs a working serial console!).
This information is obtained from the serial interface:
Type tpl in order to get into boot shell. This are the env parameters:
The general information and steps of using serial port, serial port cable, serial console etc, can be found at Serial Console.
Below is the specific information about the different hardware versions of TL-WR740N.
The serial headers are not completely connected (a voltage divider and capacitor are left out, so the headers are dead), but a serial connection can still be established by soldering directly to two of the empty pads. The result is a bit unstable (router output is often partially lost) and can probably be improved electrically.
The v4.23 uses the standard TP-Link pinout, however the TX pin is not connected to the CPU. In order to make the TX line working, the two points on the bottom side of the PCB must be connected with a small wire. The pin at the SOC is labeled TP18, the one at the serial connector is labeled TP28. The RX line is 5V intolerant! So the connection needs a 3.3V RS232 level shifter. Pins on the connector on the photo are TX-RX-GND-3V3(VCC) (from left to right).
- Hook your routers WAN ethernet port up to your network
- Hook up the serial console as explained in the section "serial console" and do the "tpl" trick to get console access
- 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
- Double check that the output of printenv lists the IP addresses you just set. Now we can load the firmware over TFTP with "tftpboot 0x81000000 openwrt-ar71xx-generic-tl-wr740n-v4-squashfs-factory.bin":
tftpboot 0x81000000 openwrt-ar71xx-generic-tl-wr740n-v4-squashfs-factory.bin erase 0x9f020000 +0x3c0000 cp.b 0x81000000 0x9f020000 0x3c0000 bootm 9f020000
General debricking advices are described here.
I did not managed to discover any method that is able to recover a bad firmware without soldering the serial cable.
For debricking with a working serial cable using TFTP follow the steps descibed in TP-Link WR741ND TFTP Installation.
For the (box branded) WR740N v2.4 and v4.23 the below works for recovery from nasty stuff like dropbear lockout, mtd overlay size problems or other software misuses :
- Unplug the router's power cord.
- Connect any router LAN port directly to your PC.
- Configure your PC with a static IP address: 192.168.1.2
- Plug the power on to the router.
- Wait until the "SYS" LED starts flashing repeatedly.
- Press the "QSS" button (on the front/back of the router) → the "SYS" LED will now start flashing at a faster rate.
- Login to the router by using telnet to connect to the IP address 192.168.1.1 → there will be an immediate unauthenticated login to a root shell.
- mount_root - will mount the normal root filesystem.
- firstboot - all settings will be reset.
- /rom/sbin/reboot - will reboot even without a mounted filesystem.
toh/tp-link/tl-wr740n.txt · Last modified: 2013/05/26 17:58 by phobosk