Category Archives: wnr3500L

Debricking NETGEAR WNR3500L using Arduino

Some time ago I had problem to access my router Netgear wnr3500L using ethernet.

I solved  using an Arduino Uno and the sketch below, to access router console via serial TTL interface.

void setup ()
{
// Disable Atmega serial line
// We want use only USB-serial adapter
//
pinMode (0, INPUT);
pinMode (1, INPUT);
}
void loop ()
{
}

Just compile and upload to arduino card.

Or remove atmega chip. The arduino board work as serial TTL 5v without atmega.

You can get TTL pinout from http://wiki.openwrt.org/toh/netgear/wnr3500l
I just put an 1KΩ resistor between Arduino and router. It works, and did not burn my router serial port. But use at your risk.

Arduino | WNR3500L
———————
RX(0) —–1KΩ—- TX
TX(1) —–1KΩ—- RX
GND ————– GND

The right and most simple way is create an voltage divider to adjust correct TTL level voltage to router RX (3.3V).

TX(1)
|
10k
|——-RX
10k
|
10k
|
GND

Open prefer serial console. I used screen on *nix. (screen /dev/tty.usbmodem411 115200,8,n,1)

And voila.

CFE for WNR3500L version: v1.0.38
Build Date: Wed Mai 24 18:40:04 CST 2013
Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
Found a 8MB ST compatible serial flash
et0: Broadcom BCM47XX 10/100/1000 Mbps Ethernet Controller 5.10.56.28
CPU type 0x19740: 453MHz
Tot mem: 65536 KBytes

Device eth0: hwaddr XX-XX-XX-XX-XX-XX, ipaddr 192.168.1.1, mask 255.255.255.0
gateway not set, nameserver not set
Startup canceled
CFE>

Then I can get new bin firmware via TFTP.

Now my wnr3500L works fine again.

References:
http://wiki.openwrt.org/toh/netgear/wnr3500l
http://www.myopenrouter.com/page/howto

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