Hello all,

I've bricked my tp-link mr3220 the other day while trying to install openwrt. I've bought a CA-42 cable to try to use the serial port, but it's just not working. I'll describe everything I did, hope it won't be too long.

Firstly, I've assembled my cable following the instructions from:

http://buffalo.nas-central.org/index.ph … _the_Cable

My cable is a CA-42, but it's a bit different because it has 6 cables (vs. 3 in the tutorial), pin '2' exits and is connected and pin 4 (3.3v out) is connected too.

Anyway, I followed the instructions there and apparently it worked because I was able to build a loopback cable. That is, I twisted tx and rx and could see the characters I typed in minicom echoed back.

Then I soldered tx, rx and gnd in the PCB as explained here:

http://wiki.openwrt.org/toh/tp-link/tl-mr3420#serial

Note that I did not solder vcc, because this cable is said to be device powered (as proved by the loop back cable). I'm not using a pullup resistor either.

I connect the USB cable, fire up minicom, turn on the router and noting happens. Absolutely nothing. I've already soldered again the cables, but it just doesn't work.

Yesterday I was googling for more information on this and found about the failsafe option. This worked! I can telnet into the router, but I really would like to make the serial port to work. Within the router I did:

# echo akndksad >> /dev/ttyS0

But did not see anything on the machine. And if I do "cat /dev/ttyS0" I see a continuous string of garbage.

Any ideas what's wrong and/or how to debug this? I could provide a picture of my PCB if this helps

Thanks!