The Asus RT-N16 is a middle class router from 2010 with gigabit ethernet and 802.11n draft. It is based on the Broadcom BCM47xx SoC platform.

Note: The wireless works fine both with b43 and brcmsmac kernel modules. By default b43 module is used. If you plan to use 802.11-n capable brcmsmac module instead you should:

• remove kmod-b43 package,
• install kmod-brcmsmac package,
• delete /etc/config/wireless file
• reboot

For me, b43 did not "work fine". It did work, but router was rebooting semi-randomly (from 10 mins to 4 hours between reboots). After some experiments, I discovered that heavy wifi traffic (two parallel flood pings, ala "ping 192.168.1.1 -f -s1400") make router reboot in less than 3 minutes. With brcmsmac, the same hardware works fine. (Tested on 15.05.1)

UPD: as an alternative can be used proprietary Broadcom module broadcom-wl, in package list named kmod-brcm-wl.

Installing process

# removing previous modules 
opkg remove kmod-b43 kmod-b43legacy kmod-mac80211 kmod-cfg80211 kmod-brcmsmac
# installing proprietary module and supported packages
opkg update; opkg install kmod-brcm-wl nas wlc wl 
# cleaning up wireless configuration and rebooting device
rm -f /etc/config/wireless; reboot 

Working config

config wifi-device 'wl0'
        option type 'broadcom'
        option txantenna '3'
        option rxantenna '3'
        option hwmode '11ng'
        option channel '6'
        option htmode 'HT40'
        option txpower '24'

More about modules comparison can be read here, here, configuring example found on OpenWRT and 802.11n on Asus WL-500W (same wireless SoC).

The Barrier Breaker release have almost full support of Asus RT-N16. The following is a list of everything that needs polish in order to update this device's status to 'fully supported'.

• Like for most wireless solutions based on BCM4718, it uses the reverse engineered b43 driver by default. With this driver only 802.11g is supported, but you can easily get wireless 802.11n working by installing the Broadcom open source brcmsmac driver. Alternatively, for more functionality like 40Mhz bandwidth you can use the closed source STA drivers, broadcom-wl. Advanced WiFi configurations have to be done via the wl utility however. For installation, refer to the bcm47xx platform's page.
• There are reports that the generic firmware is not accepted by the ASUS web interface, but it may work with TFTP. Thus a build is required that is tagged with a header such that it is accepted. A patch should be created for OpenWrt, adding support for generating a proper Asus firmware.
• The reset button works only to take you to Asus's failsafe mode. Clearing NVRAM is done with the button labelled by WPS. The 'real' reset button can also put the router in OpenWrt recovery mode, see failsafe.mode.

Just go to Administration→Upgrade and select your https://downloads.openwrt.org/chaos_calmer/15.05.1/brcm47xx/mips74k/openwrt-15.05.1-brcm47xx-mips74k-asus-rt-n16-squashfs.trx (tested for Tomato 1.28)

Below instructions install bleeding edge.

this is how i installed it from ddwrt ssh session:

make sure linux is on there then, to install bleeding edge :

or, to install 15.05.1 (works!) :

after router reboots, you should be able to telnet to 192.168.1.1 and go from there.

be sure to reset to default settings using :

otherwise things will be missing and misconfigured.

→flash.layout for a detailed explanations.

• ASUS has 4 partitions:
  • 0x 0000 0000-0x 0004 0000 : "boot"
  • 0x 0004 0000-0x 01fe 0000 : "linux"
  • 0x 001d ff88-0x 01fe 0000 : "rootfs"
  • 0x 01fe 0000-0x 0200 0000 : "nvram"

Note that (at least for some version of the Asus firmware) the generic OpenWrt builds are not accepted by the ASUS web interface. Hence, there is a need for a special build for initial flashing. A patch still needs to be made for this but it is not worked on as of yet. Until then, you can either use the methods below, or use the DD-WRT file for initial flashing and then flash OpenWrt through the DD-WRT web interface. The page at wl500gp has detailed backup, flash, & recovery information which should largely apply to the RT-N16 as well.

Flash from a Windows PC using the Firmware Restoration utility. (Download or install the Firmware Restoration Utility to your PC.)

The Asus RT-N16 has a failover mode, like the DIR-600 Bx (X=1,2).

To launch the recovery mode disconnect power from the router first.

Hold the WPS button while plugging in the power to the router to reset nvram, router will restart 2x. Hold the RESET button while plugging in the power to the router to get into recovery mode in which tftpd will be listening. The power LED should start to blink (low frequency, ~1 time every 3 seconds). Retry if that doesn't work for you.

The router IP in the recovery mode is 192.168.1.1 255.255.255.0.

Configure your PC (don't use 192.168.1.1)

Ping 192.168.1.1 should give a response.

Launch the Firmware Restoration utility, select the firmware and press the Upload button.

Ignore the warning, we want to be on OpenWRT!

It may now take several minutes. Be patient and enjoy a cup of tea or coffee.

Reconfigure your PC back to DHCP

Connect to http://openwrt.lan and proceed with the basic configuration.

This may work with other tftp utilities, too.

The Asus RT-N16 has a failover mode, like the DIR-600 Bx (X=1,2).

Get a tftp client, Since Ubuntu is a popular choice snag it :

Now to modify the router … To launch the recovery mode disconnect power from the router first.

Hold the WPS button while plugging in the power to the router to reset nvram, router will restart 2x. Hold the RESET button while plugging in the power to the router to get into recovery mode in which tftpd will be listening. The power LED should start to blink (low frequency, ~1 time every 3 seconds). Retry if that doesn't work for you.

The router IP in the recovery mode is 192.168.1.1 255.255.255.0.

Configure your box to use an ip 192.168.1.15; this specific IP is required in order to transfer via tftp.

Ping the interface to be sure it's up :

Ctrl+C to break.

If you get ping responses then it's up and ready to flash.

Set it to binary mode transfer :

upload the firmware :

When it's complete the router will be writing the firmware and may not automatically reboot. Wait up to 5 minutes, then power off the router and plug it back in.

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

Switch ports 1-4 are for the LAN, and 0 is for the Internet (WAN) port. Note that the switch ports are the opposite of what is labeled on the device; thus switch port 1 is labeled LAN4, etc. Switch port 8 is the internal connection to the CPU. Not sure what happened to 5-7 but it's assumed they're just not wired out to anything.

If you forgot your password, broken one of the startup scripts, firewalled yourself or corrupted the JFFS2 partition, you can get back in by using OpenWrt's failsafe mode. If you are unsuccesful solving the problem with OpenWrt's failsafe mode, i.e. you have bricked the device, you can use Asus's failsafe mode to flash a new image.

Follow these steps to boot into the OpenWrt failsafe mode:

• Unplug the router's power cord.
• Connect the router's LAN1 port directly to your PC.
• Configure your PC with a static IP address between 192.168.1.2 and 192.168.1.254. E. g. 192.168.1.2 (gateway and DNS is not required).
• Plug the power on and wait for the DMZ LED to light up.
• While the DMZ LED is on immediately press any button (Reset and Secure Easy Setup will work) a few times .
• If done right the DMZ LED will quickly flash 3 times every second.
• You should be able to telnet to the router at 192.168.1.1 now (no username and password)

NOTE: The root file system in failsafe mode is the SquashFS partition mounted in readonly mode. To switch to the normal writable root file system run mount_root and make any changes. Run mount_root now.

• Forgot/lost your password and you like to set a new one by running:
  passwd
• Forgot the routers IP address. Retrieve it by running:
  uci get network.lan.ipaddr
• You accidentally ran ipkg upgrade or filled up the flash by installing packages that are too big. In the latter case clean the JFFS2 partition and start over by running:
  mtd -r erase rootfs_data

If you are done with failsafe mode power cycle the router to boot in normal mode.

Since this is an Asus product you can also use the failsafe mode (included in the boot loader). Press and hold the "Reset" button on the back of the device, then plug it in. When the 'PWR' light blinks slowly then it is listening in TFTP mode (~ once every 3 seconds). The default address is 192.168.1.1. If this is not pingable, do the NVRAM reset first, described as follows.

To reset the NVRAM, hold the "WPS" button and plug in the router. When the 'PWR' light is blinking quickly, then when you let go of the WPS button, the router will perform a reboot, wipe and reboot again. Note that clearing NVRAM does not clear much of OpenWrt's configuration, unlike other router software which keep configuration data in NVRAM. Since OpenWrt's configuration is kept in the main JFFS file system, using UCI configuration files, if you cannot boot normally you can reset or change this with OpenWrt's failsafe mode. See also flash.layout.

This CC snapshot works on RT N16. Look at http://downloads.openwrt.org/snapshots/trunk/brcm47xx/mips74k/.

If you want to compile Target System (Broadcom BCM947xx/953xx) Target Profile (Broadcom SoC, all Ethernet, BCM43xx WiFi (wl, proprietary))

For Barrier Breaker: Target System (Broadcom BCM47xx/53xx (MIPS)), Subtarget (MIPS 74K), Target Profile (Broadcom SoC, BCM43xx WiFi (proprietary wl)).

Initially WLAN LED is not triggered by Wi-Fi driver. Edit /etc/config/system to enable it (tested with brcmsmac):

config led wlan_led
        option name 'WLAN'
        option sysfs 'bcm47xx:blue:wlan'
        option trigger 'netdev'
        option dev 'wlan0'
        option mode 'link tx rx'

• Note the serial header on the board at at J2, you can see on the front of the board between the usb ports and the asus logo. It even came with pins and markings. Gnd, Vcc, Rx, Tx are clearly marked. They fit with a 4pin cd-rom audio or 4pin fan plug. I was able to get a serial terminal up using a CA-42 nokia usb-ttl serial adapter (found some ~$3.50 plus shipping on amazon), similar to the instructions on nslu2-linux.org. Using a usb-ttl serial adapter it is only necessary to have the Gnd, Tx, and Rx connected, not the Vcc.

Note: This will void your warranty!

How to connect to Serial Port :

You will need a TTL device to connect. These are available cheaply online from many different retailers. I picked up mine here :

http://www.ebay.com/itm/251082091781?ssPageName=STRK:MEWNX:IT

a PL2303 USB To RS232 TTL Converter Adapter Module.

This exposes a serial device to OS via USB. Connection should be made to the header on the RT-N16 matching RX→TX and TX→RX. Connect GND to GND. Then open up a terminal application, like PuTTY, and connect with 115200 baud, with 8 bits of data, no parity (8N1). Connecting VCC doesn't hurt.

This is recognized in WinXP, Win 7 and Linux (Ubuntu 11.10 checked). Drivers here : http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=225&pcid=41

For connection in windows, use PuTTY. Find the COM port by using Device Manager to see where it has been assigned.

For connection in Linux : review serial pages for the connection.

There have been attempts to use the PCIe interface. See http://linux-mips-org.10913.n7.nabble.com/Re-brcm4716-and-PCIe-td56191.html

After unplugging and replugging the router's power it became unresponsive, even the LEDs were not lightning up. I opened the router to find a capacitor near the power supply (most likely a filter cap) which seemed slightly popped. The capacitor was a 680uF 16V. I didn't have any capacitor with the same specs at hand, so I replaced it with a capacitor with higher voltage/capacity ratings (1000uF 25V). After replacing the capacitor the router started working and the router configurations were still intact.

• ASUS factory firmware and sources available from ASUS support (choose OS "Others")
• RT-N16 DebWrt wiki page
• Tech Info Depot Wiki
• WikiDevi
• Getting 802.11n working using closed source broadcom-wl driver http://blog.tklee.org/2014/11/use-80211n-on-asus-rt-n16-with-openwrt.html

Development information:

• Forum thread for the latest info
• George Kashperko's patches which were used to get the N16 working

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