Some days ago my fonera stopped working without any (obvious) reason I think that there was maybe a firmware-upgrade initiated by Fon, which did not complete correctly.

Howsoever I had to open the fonera to connect to its serial console. For doing this I found the very good page of the OpenWRT-project describing the fonera.

So I remembered my MAX232 and built up a small circuit for level-shifting the TTL-levels of the fonera to the RS232-levels of the PC serial interface. As I could not find any documentation about this on the net, I will explain it here shortly:

I used an USB-to-mainboard.connector from an old computer-case to connect to the 3 important pins (RX, TX, GND) of the fonera. In the two pictures RX is the blue-white, TX the yellow and GND the grey wire comming from the fonera. So connect these wires to the MAX232 as shown in the left picture (click for larger view). The MAX232 needs 4 capacitors, 1µF each. See the MAX232-datasheet (page 7) for detailed information how to connect them. On the RS232-side GND is the pink, TX is the green and RX the yellow wire.

If everything is connected and (hopefully) working correctly, disconnect the fonera’s serial interface again, power the fonera up and reconnect the serial-cable after one or two seconds. If you don’t do it this way, the fonera will not boot up or will give you very strange characters instead of the boot-prompt. (It took me quite long to figure this out… ).

If you want to flash OpenWRT to your fonera, continue like described here. I installed it to my fonera – and bricked it once again, because I made some mistakes But after another try it is working now very stable Currently it is running here as an WLAN-AP, DHCP- and DNS-server using OpenWRT Kamikaze 7.07.

If you want to restore your fonera-firmware, you can follow these instructions.

So, good luck!