NOTE: Requires K2.6 -nv60k, Do not flash anything else.
NOTE: During configuration or flashing a device, the only things that should be hooked to the device is the computer and power.

 This section is in need of cleanup!

Platform

Serial Num. = 01C10C
FCC ID = Q87-E4200
CPU Type = Broadcom BCM4718
MIPS Rev = ?
CPU Speed = 480Mhz
Bus = ?
Flash Type = SPI Flash
Flash Chip = Macronix MX25L12845E/ Winbond W25Q128BV
Flash Size = 16MB
Max Firmware Size = ?
RAM Size = 64MB
RAM Chip = Hynix 
nvram Size = 60kb
Switch = Broadcom BCM53115
Port-based vlan = ?
802.1q vlan = ?
Ethernet Port Count = 1-10/100/1000-WAN 4-10/100/1000-LAN
Wired Standard = IEEE 802.3/3u/3ab
boot_wait = ?
bootloader = CFE
Flash Card Socket/Type = No
SD/MMC Mod Support = No
MiniPCI slots = No
PoE = No
Power = 12V/2A
Color of LEDs = top-front 2x White/ back 5x Yellow, 5x Green
Size = 1
USB = 1x USB 2.0
Serial Port = Yes
JTAG Port = Yes (2x connector 2.3 standard)
Supported by TJTAG/Version = 
Special Features = ?

Radio (wl0)

Wireless Radio = Broadcom BCM4718 (SoC)
WLAN DSP processor = ?
Antenna Connector Type = Internal
Wireless Standard = IEEE 802.11b/g/n
WiFi Operating Frequency = 2.4GHz (2 x 3)
 802.11n = up to 300Mbps
 802.11g = 6, 9, 12, 18, 24, 36, 48, 54Mbps
 802.11b = 1, 2, 5.5, 11Mbps
Radio cor_rev = ?
Radio Capabilities = ?

Radio (wl1)

Wireless Radio = Broadcom BCM4331 Intensi-fi Single-Chip
                 802.11n Transceiver
WLAN DSP processor = ?
Antenna Connector Type = Internal
Wireless Standard = IEEE 802.11a/n
WiFi Operating Frequency = 5GHz (3 x 3)
 802.11n = up to 450Mbps
 802.11a = 6, 9, 12, 18, 24, 36, 48, 54Mbps
Radio cor_rev = ?
Radio Capabilities = ?

• http://www.wikidevi.com/wiki/Linksys_E4200
• File:Certificate WFA9933.pdf
• Linksys E4200 Router released - DD-WRT
• Linksys E4200 available now! - TomatoUSB
• Cisco Linksys E4200 Maximum Performance Wireless-N Router Reviewed at smallnetbuilder.com

Warnings

• The E4200 is very sensitive to the nvram size. The only safe nvram size identified for this router is an nvram size of 60kB. Recovery from a firmware with the wrong nvram size requires use of a jtag cable to erase the nvram.1

• Support for the E4200 is still very much a work in progress at this time, outstanding issues reported have included WAN stability, and both 2.4GHz and 5GHz Radio stability.

Flashing Process

• Perform these steps when flashing from the stock linksys GUI:

1. Disconnect all cables and wireless clients.
2. Perform a 30/30/30 reset on the device.
3. Flash the latest E4200 specific mini build (dd-wrt.v24-<build number>_NEWD-2_K2.6_mini-e4200.bin) to the router.
   1. The E4200 specific mini builds are also -nv60k builds, they just aren't labeled as such.
4. Wait approximately 5 minutes for the flashing process to complete.
5. Perform a 30/30/30 after the device has successfully updated.
6. Flash to larger build of your choosing (Mega, Big, std_usb_nas, OpenVPN, VoIP.)
   1. WARNING Only flash -nv60k builds, flashing anything else to the router will brick it as noted above (dd-wrt.v24-<build number>_NEWD-2_K2.6_<build type>-nv60k.bin)
7. If flashing to another build always perform a 30/30/30 before and after flashing.

 This section is in need of cleanup!

• tomato-E4200-test-5 - Test Build
• Toasman's latest Builds - Up to date (15.11.2011)

 This section is in need of cleanup!

If dd-wrt 17084 and up is already on the router, builds with nv60k in the name can be used for upgrade.

• You can always revert back to stock firmware.
• Download the latest E4200 firmware from linksys site.

1. Disconnect all cables and wireless clients.
2. Perform a 30/30/30 reset on the device.
3. Login and select the stock firmware file and flash, make sure to select "reset to defaults" on the drop down menu when flashing.
4. Wait approximately 5 minutes for the flashing process to complete.
5. Perform a 30/30/30 after the device has successfully updated.

JTAG Pinouts

 This section is in need of cleanup!

JTAG Recovery

 This section is in need JTAG Recovery Instructions!

Serial Pinouts

 This section is in need of cleanup!

Hyper terminal Setup in Windows XP

In Windows XP, Click Start Button - All Programs - Accessories - 
   Communication - HyperTerminal
Enter a name for the connection, Click ok
Choose com port you adapter is plugged into, Click ok
Set:
 Bits per second = 115200
 Data Bits = 8
 Parity = none
 Stop bits = 1
 Flow control = none
Click ok
Click File - Save As, and select a place to save it to so you 
             don't have to enter the settings again.

Putty Setup in Windows XP

After installing putty, run it
 Serial line = The COM port your using for serial (ie. COM3)
 Speed = 115200
Click on Serial under Connection
 Serial line to connect to = same as above (Serial line)
 Speed (baud) = 115200
 Data bits = 8
 Stop bits = 1
 Parity = None
 Flow control = None
Click Session
 Enter a name for your connection under saved sessions
Click Save
Click Open

Serial Recovery

 This section is in need of Serial Recovery Instructions!

The USB port is where you can connect an external USB hard drive or flash drive. Which can do a multitude of things. You can use in as a NAS, storage for a FTP server, use Optware to run external programs like torrent software, samba for sharing files to your network, share a USB printer with your network... The list of possibilities is long, it just takes a little research.

ProFTPd is included in most the newer builds of dd-wrt. Check the features chart to be sure.

A ftp server, file sharing, and a media sever is included in TomatoUSB if your device is compatable.

 This section is in need of cleanup!

Eko

Just a note on upgrading e2000, e3000 and e4200 routers already running dd-wrt. These need -nv60k.bin builds, but this will work only from now on. So for initial upgrade use proper mini-eXXXX.bin build and then upgrade with -nv60k.bin build. If you flash a -nv64k.bin, your E4200 will bricked!

• As is explained in http://www.dd-wrt.com/wiki/index.php/Wireless-N_Configuration make sure that you use AES security for your wireless N network. Do not use TKIP or the wireless speed will revert to the g standard and that would be a pity. AES+TKIP is also allowed.

• Both the 2.4 and 5GHz Radios run at a stock transmitting power of 100mW, decreasing the transmitting power to a value between 40 & 50mW has seemed to help stability.

5GHz Wireless Transfer Speed Tips

These are suggestions that are being recommended inside the E4200 forums thread to improve wireless performance on the 5GHz radio. Recommendation from LiteUp! and basmaf

• Enable Frame burst
• Set Afterburner to Auto (this will only have an effect if your wireless clients use Broadcom radios. Disable Afterburner, if you use two Routers in AP <->Client Bridge-Mode)
• Highest transfer rates are being achieved on channels 100-128. Do not set channel to Auto!
• Be patient, let SNR settle down before testing speeds.