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falling_soul86
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Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 12:52 pm

Please, need to unbrick a wireless router tplink WR740N.

I was surfing the web looking for info, and I saw something about use a mini stick "usb to TTL" for use 3.3V and 5V for the comunication, there is a way to use my good Pi partner to help me on this :) ???

Thanks in advance.

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rurwin
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 1:20 pm

I just took a quick skim of the Internet, and it seems the router runs on 3.3V. If this is true, then you can use the RaspPi's serial port on the GPIO connector, without any additional hardware.

However, there are various hoops you have to jump through to use that serial port. You have to stop the OS using it as a boot console for example. Then you have to find a terminal emulation app. Then you need to build a cable and solder it to the router. It is not a job for the faint of heart, but good luck if you go ahead.

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falling_soul86
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 1:39 pm

I got a completely lecture, and I am more than ready to try xD, do you recomend any terminal emulation application?, in that matter will be the first time to try jeje, but about the soldier wires, I'm a dynamo.


Pd. How is the map in the raspberry pinout? about where I plug the Rx Tx and the ground (Gnd). Thanks Again, I promess make a full manual of everything with pics for the raspberry comunnity.

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DirkS
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 1:56 pm

How is the map in the raspberry pinout?
https://www.google.co.uk/search?q=raspb ... 20&bih=947

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falling_soul86
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 2:11 pm

Excellent, I got print the pinout, I'm preparing myself to this :geek:

ohmmmmmmm

Pd. the last piece is the Terminal Emulation, this emulation can be done inside Raspbian?

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DirkS
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 2:24 pm

falling_soul86 wrote:the last piece is the Terminal Emulation, this emulation can be done inside Raspbian?
You could use minicom. You'll probably have to install it first.

Gr.
Dirk.

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falling_soul86
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 2:26 pm

From : "http://wiki.openwrt.org/toh/tp-link/tl-wr740n"

"The v4.23 uses the standard TP-Link pinout, however the TX pin is not connected to the CPU. In order to make the TX line working, the two points on the bottom side of the PCB must be connected with a small wire. The pin at the SOC is labeled TP18, the one at the serial connector is labeled TP28. The RX line is 5V intolerant! So the connection needs a 3.3V RS232 level shifter. Pins on the connector on the photo are TX-RX-GND-3V3(VCC) "

About the pinout, must be in the raspberry this way?:

Router <-> Raspberry Pi

Vccpin --- Pin1
Rxpin --- Pin 10
Txpin --- Pin 8
Gndpin --- Pin 6, 9, 14, 20 or 25

I'm seeing my router working properly soon :idea:

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gregeric
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 2:35 pm

Do NOT connect the Vcc's together, just ground & the TX/Rx lines crossed over. Damage may occur if you do.

In your scheme above, you do not have Rx/Tx crossed over. So router Tx goes to Pi Rx on GPIO header pin 10, router Rx goes to header pin 8 on the Pi.

Linux screen command is a handy tool, both on the Pi and on the router when you get openwrt on it. I can't remember whether it's included in the standard Raspbian images, but it's just a "sudo apt-get install screen" away if not.

Then
screen /dev/ttyAMA0 115200
will open a serial terminal for you at 115200 baud ready to talk to the router.

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falling_soul86
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 3:43 pm

Cool, so must be in this way, right?

Rxpin --- Pin 8
Txpin --- Pin 10
Gndpin --- Pin 6

about the Vcc, don't need to be plugged?

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gregeric
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 5:12 pm

Correct, just those three wires, no connection to Vcc.

Have you disabled the Raspbian boot console's use of /dev/ttyAMA0? It's an option on the advanced section of sudo raspi-config (you may need to choose the self-update option if it's not there).

Connect those three wires, boot the Pi, then start your preferred terminal app eg screen as per my recommendation above.

Next apply power to the router - you should see its boot log on the Pi.

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falling_soul86
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Re: Unbrick a wireless router using the I/0 pings

Mon Sep 15, 2014 5:18 pm

Excellent thanks to all of you guys, I will be trying as soon as get out of work jeje, in around 5 hours I will be testing :)

WISH ME LUCK..

May the Pi be with me.

Pd Greg, nice post 100 :D

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