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severity (level) requirement Gnublin family
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RS232 Module

In addition to the other modules for Gnublin now there is also a RS232 module that extends the Gnublin by two RS232 interfaces.


Each of this two interfaces owns once an output with TTL-level (3-5V) and one with RS232 level (6V and up).

In the picture you can see that the left interface is connected by a ribbon cable with RS232 level to a COM connector and the rights interface is connected via a ribbon cable with a USB to TTL adapter.

Control with Gnublin Distribution

The driver for the module and the software picocom is in the latest version of the Gnublin Distribution (from 2/21/13) already included in the root file system.

The control of the module works as follows:

load the module

First of all, the module must be plugged in and the Gnublin have to be started. Then you can already load the driver with the following command:

modprobe sc16is7x2

Then two new device files will be created:

  • /dev/eser0
  • /dev/eser1

The device-File eser0 belongs to the pins on the side of the oscillator and the pins eser1 on the other side.

start picocom

At the Gnublin start picocom with the following instruction:

picocom -b 115200 /dev/eser0


picocom -b 115200 /dev/eser1

terminate picocom

To terminate picocom on the Gnublin, you should be sure, that you have another terminal programm on your host computer.

This is necessary for the following reason:

If you are connected to the Gnublin by picocom and start another instance of picocom on the Gnublin, you can not terminate the session without problems. The problem is the result of the keyboard shortcut (ctrl + A, ctrl +X), which terminates both picocom connections. This has the consequence that the connection is terminated to the Gnublin but picocom on Gnublin continues.

Here comes the second terminal program into play, I recommend the program hterm from here.

After you downloaded the correct version, you could run the file. Then you should do the following configuration.


It is important to choose the right device (connection to the Gnublin). If everything fits, press the button Connect.

After that, on the bottom part of the programm change the datatype from ASC to DEC:


Now type in the box next to the data type selection, the number 1 and confirm with Enter. Then tap the number 24 and confirm again withEnter.

Now picocom should be terminated on the Gnublin and you can reuse it as usual.

If you want to use another terminal program, you simple have to send an decimal '1 'followed by a decimal '24'.

  • 1 decimal equals STRG+A
  • 24 decimal equals STRG+X
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