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
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).


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
CPU type 0x19740: 453MHz
Tot mem: 65536 KBytes

Device eth0: hwaddr XX-XX-XX-XX-XX-XX, ipaddr, mask
gateway not set, nameserver not set
Startup canceled

Then I can get new bin firmware via TFTP.

Now my wnr3500L works fine again.


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