The TL-WA901ND is a lowcost b/g/n wireless access point, capable of running OpenWRT.

• Version 1.x of this device is fully supported since r22353.
• Version 2.x of this device has been reported to work fine with r29330 (no earlier versions tested).

• Atheros AR7240 CPU
• 4 MB flash memory
• 32 MB RAM
• Atheros AR9285 wireless chip

The serial console connector has the usual TP-Link pinout: RX - TX - GND - +5V (Power connector)

However, as with other TP-Link models, a little hardware mod is required in most circumstances to get the serial console working properly. Without this mod, you might see garbled chars when using a Prolific PL2302-based level shifter. This is because TP-Link employed some sort of voltage divider as has been reported for the TL-WR741ND as well: RX will have a high level of only 1,7V, whereas the CPU pin itself has the usual 2,5V.

To fix this, you must remove the 2x 5k6 resistors R249 (→ 3.3V) and R251 (→ GND) as well as the capacitor C278. You might want to replace it with a 1K resistor to protect the CPU pin, otherwise bridging the pads will do the job but offers the risk of damaging the CPU port.

After this, the console will be accessible at 115200bps 8N1. Type "tpl" to escape automatic boot and reach U-boot's prompt. Note this is a crippled U-boot: you can not modify the environment settings permanently which is why OpenWrt kernels ignore the kernel command line.

Comment: The WR741ND had the same serial connection, and I fixed it without altering the board, by simply placing a 10k pullup resistor between the TX and 3.3V pins.

Using the serial console, new firmware versions can be loaded via TFTP and flashed as follows. This assumes your TFTP server is reachable at 192.168.1.100. You can change IP addresses with:

setenv ipaddr a.b.c.d
setenv serverip e.f.g.h

TFTP loading and flashing is done by issuing:

tftpboot 0x80000000 openwrt-ar71xx-tl-wa901nd-squashfs-factory.bin
erase 0x9f020000 +0x3c0000
cp.b 0x80000000 0x9f020000 0x3c0000

If successful, the firmware can now be started with

bootm 0x9f020000

• Atheros AR9132 CPU
• 4 MB flash memory
• 32 MB ram
• Atheros AR5416 wireless chip
• RTL8201 Ethernet chip

The serial console connector has the usual TP-Link pinout: RX - TX - GND - +3.3V (Power connector)

It's 115200 8N1, software flow control. It's a TTL serial port, so don't plug it directly into a RS232 port. You have to build a TTL-RS232 adaptor to attach your WA901ND to your computer:

With that, you can now use a null modem cable to attach it to your PCs COM port.

To access the boot menu, type "tpl" (without quotes) when you see "autobooting in 1 seconds".

The ethernet port is not enabled in the boot loader. Because of that, TFTP cannot be used to transfer the firmware.

You can install OpenWRT via the web interface using the pre-compiled trunk .bin file openwrt-ar71xx-generic-tl-wa901nd-v2-squashfs-factory.bin

You will want to configure your new OpenWRT by:

1. set your static IP to 192.168.1.x

2. telnet into the device either through putty or unix terminal:

telnet 192.168.1.1

Full guide found here: First Login

3. Then you will want to secure your router:

root@openwrt:~$ passwd
Changing password for root
New password:
Retype password:
Password for root changed by root
root@openwrt:~$ 

4. then you will want to configure your router to your liking, I suggest starting here Dumb AP 5. then you will want to configure your router with LuCI:

opkg update

opkg install luci

/etc/init.d/uhttpd enable
/etc/init.d/uhttpd start

(the full guide can be found here LuCI Essentials)

ar7100> loady

Now send the file openwrt-ar71xx-generic-tl-wa901nd-v2-squashfs-factory.bin using the Ymodem protocol with your terminal emulation.

After the filetransfer has been completed type:

ar7100> erase 0xbf020000 +0x3c0000
ar7100> cp.b 0x81000000 0xbf020000 0x3c0000
ar7100> reset