Make your own router with WRTNode - controlling WRTNode through the serial console port

Today we will see how to add a converter from TTL to serial port, by connecting to port UART of our WRTNode; to establish a connection and access as well to a Terminal.


It is the same thing that we have with Raspberry PI in one previous entry, the only thing different is the pinout on the side of the Board; and in this case are going to feed the module with 3V.

Plate converter we use, can be supplied with 3V or with 5V; by what will be useful for Raspberry PI, WRTNode, and even for Arduino and the vast majority of market development boards.

Screenshot of 2014-11-15 23:03:18

This is very useful, Since it allows us to access the system as root without entering the password, and we can manage the router in the event of loss of the same, and even change it; and the routers with this type of factory implemented connections tend to be quite expensive.


Some converters modules of TTL to RS232 not they should feed externally under any circumstances since they receive the power from port series, and we could burn our WRTNode by supercharging; in our case we will use a converter based on chip SP3232EEN, that if we feed from WRTNode through pin VCC Converter plate.

Pinout and extracted from the datasheet of SP3232E wiring diagram, identical to SP3232EEN.

Pinout and wiring diagram extracted from the datasheet of SP3232E, identical to SP3232EEN.

The first thing we must do is to connect the converter's TTL to RS232 to port UART of WRTNode as we can see in the table below, and in the following diagram; the complete pinout of WRTNode You can find it in this previous entry.

WRTNode Plate TTL to RS232 converter
GPIO 65 (+3V)
GPIO 75 (TXD2)
GPIO 62 (RXD2)

Connection diagram.

We will then install ckermit, a software to control the serial port.

usuario@maquina:~$ sudo apt-get install ckermit

The first thing we have to do, It is to tell the device that will work; in my case is an adapter USB to RS232, Therefore the assigned route is /dev/ttyUSB0 and with the option -l We are going to indicate to connect.

usuario@maquina:~$ sudo kermit -l /dev/ttyUSB0

Once opened ckermit, It only remains to establish the parameters for the connection, that you are the same use with Raspberry PI in a previous entry; Let's see how to do it.

(/home/usuario) C-Kermit> set speed 115200
(/home/usuario) C-Kermit> set parity none
(/home/usuario) C-Kermit> set flow-control none
(/home/usuario) C-Kermit> set carrier-watch off
(/home/usuario) C-Kermit> connect
Connecting to /dev/ttyUSB0, speed 115200
 Escape character: Ctrl-\ (ASCII 28, FS): enabled
Type the escape character followed by C to get back,
or followed by ? to see other options.

Now press the key Enter, and we will see the welcome message of OpenWRT Barrier Breaker; We must remember that with this system path will not ask us for the password to login as root, Since login by default in BusyBox ES without password.

BusyBox v1.22.1 (2014-08-13 19:31:12 UTC) built-in shell (ash)
Enter 'help' for a list of built-in commands.

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 BARRIER BREAKER (Bleeding Edge, r41508)
  * 1/2 oz Galliano         Pour all ingredients into
  * 4 oz cold Coffee        an irish coffee mug filled
  * 1 1/2 oz Dark Rum       with crushed ice. Stir.
  * 2 tsp. Creme de Cacao


If you like you can follow me on Twitter, Facebook, Google +, LinkedIn, or share it with the buttons under this publication, If you have any questions or suggestions please do not hesitate to comment.

Help us to reach more readers Share on LinkedIn
Share on Facebook
Tweet about this on Twitter
Share on Google+
Google +
Email this to someone

Leave a Reply

Your email address will not be published. Required fields are marked *