In the 2 previous articles, I explained how to set up a serial console on Ubuntu and Debian. This tutorial will now show how to connect to those serial console using another machine using a software called minicom. Minicom is a serial communication program that we will use in order to connect to a serial console. An Open Source serial communication application for Linux-based operating systems Minicom is a completely free and open source command-line software project implemented in C and designed from the offset to act as a clone of the well-known Telix application created only for the Microsoft Windows (MS-DOS) operating systems.

Serial Communication Example using Pi4J.

The following example demonstrates how to transmit and receive data using the Raspberry Pi serial port.
(A complete article on building and installing a serial port on the Raspberry Pi is available here: http://www.savagehomeautomation.com/projects/raspberry-pi-installing-a-rs232-serial-port.html)

Prerequisites

By default, the serial port on the Raspberry Pi is configured as a console port for communicating with the Linux OS shell. If you want to use the serial port in a software program, you must disable the OS from using this port. Please see this blog article by Clayton Smith for step-by-step instructions on how to disable the OS console for this port: http://www.irrational.net/2012/04/19/using-the-raspberry-pis-serial-port/

Source Code

The source code for this example is included in the github repository:
https://github.com/Pi4J/pi4j/tree/master/pi4j-example/src/main/java/SerialExample.java

JavaDoc

The following JavaDoc links are the primary interfaces used to communicate via the Pi's serial ports:

Wiring Diagram

The circuit below illustrates a RS232 serial port connected to the Raspberry Pi's GPIO header.
The following circuit can be used in conjunction with this sample code.
(A complete article on building and installing a serial port on the Raspberry Pi is available here: http://www.savagehomeautomation.com/projects/raspberry-pi-installing-a-rs232-serial-port.html)

Navigate

If you have not already downloaded and installed the Pi4J library on the RaspberryPi, then view this page for instructions on where to download and how to install Pi4J:
Download & Install Pi4J

First, locate the SerialExample.java source file in the samples folder of the Pi4J installation on the RaspberryPi.
You can use the following command on the Pi's console or SSH terminal to navigate to this path:
cd /opt/pi4j/examples

Ubuntu Serial Communication Programs

Compile

Next, use the following command to compile this example program:

javac -classpath .:classes:/opt/pi4j/lib/'*' -d . SerialExample.java

Execute

The following command will run this example program:

sudo java -classpath .:classes:/opt/pi4j/lib/'*' SerialExample

Output

To test this program you will need to connect your computer via serial cable and use a serial communications tool such as Hyperterminal or Indigo Terminal Emulator. Establish a connection using baud rate 34800 with parity set to NONE, data bits to 8 and stop bits to 1. Scrubs gift shop girl. (38400,N,8,1) Once connected you should see the following data displayed in the terminal software:

CURRENT TIME: <Date/Time> Second Line Third Line

This data should be repeated every second.

Ubuntu Serial Communication Programming

You can also submit data from the terminal software and that data should be displayed on the Raspberry Pi's console. ' />