computer network Lab 2 (reference)

Linux / UNIX minicom Serial Communication Program

Posted onin CategoriesHardware, Howto, Linux, Linux Embedded devices, Tipslast updated February 5, 2008

Linux comes with many serial text and gui based serial communication programs. My favorite is minicom – friendly menu driven serial communication program.

If you are addicted to DOS / Windows TELIX (a telecommunications program originally written for DOS and was released in 1986), minicom is for you under Linux / UNIX.

minicom Common features / usage

=> Setting up a remote serial console
=> Access a computer / server if the LAN is down
=> Connect to embedded Linux / BSD device via null modem cable
=> Connect to Cisco routers for configuration
=> Connect to dump device i.e. device w/o keyboard and mouse
=> Dialing directory with auto-redial
=> Support for UUCP-style lock files on serial devices
=> Separate script language interpreter
=> Capture to file
=> Multiple users with individual configurations

Let us see how to configure minicom for my Soekris net4801 Single Board Computer / embedded Linux device.

Install minicom

Use apt-get under Debian / Ubuntu Linux, enter:
$ sudo apt-get install minicom
If you are using Red hat Linux (RHEL) / CentOS / Fedora Linux, enter:
# yum install minicom

How do I use minicom?

First, make sure Linux has detected serial ports. Use setserial command to set and/or report the configuration information associated with a serial port.

Setup minicom

The -s option use to setup minicom. Type the following command at shell prompt:
$ minicom -s
Configure the first time when you run minicom
(Fig. 01: minicom in configuration mode)
Some terminals such as the Linux console support color with the standard ANSI escape sequences. Type the following command start minicom with colours:
$ minicom -s -c on
Minicom in configuration mode with colour console
(Fig: 02: minicom in configuration mode with color console)
When minicom starts, it first searches the MINICOM environment variable for command-line arguments, which can be over-ridden on the command line. Thus, if you have done:
$ export MINICOM="-m -c on"
Start minicom
$ minicom
minicom will assume that your terminal has a Meta or key and that color is supported. You can add MINICOM variable to your shell startup script such as ~/.bash_profile.

minicom keyboard short cut keys

Use the following keys:

  1. UP arrow-up or k
  2. DOWN arrow-down or j
  3. LEFT arrow-left or h
  4. RIGHT arrow-right or l
  5. CHOOSE (select menu) Enter
  6. CANCEL ESCape

Configure serial port

You need to configure serial port. Use up and down arrows to select menus. Press down and select Serial port setup:
Minicom serial port configuration
(Fig. 03: Configure serial port with minicom)

  • Press A to setup serial device name such as /dev/ttyS1
  • Press E to setup Bps/Par/Bits
  • Press [ESC] to exit
  • Save setup as DFL
  • Exit

More on shortcut keys

To activate help menu press [CTRL+A] followed by [Z] for help on special keys:
minicom command summary
(Fig: 04: minicom command help summary)

minicom in action

You need to connect your serial device such as router or modem using modem cable. Once connected power on device and type minicom command without -s option:
$ minicom -c on
Minicom in action - connected to one of my dump device
(Fig: 05: minicom connected to one of my embedded Linux device via null modem cable [ click to enlarge image])
The soekris embedded Linux / BSD board with AMD 266 Mhz CPU + 256M RAM. This device connected to my computer using DB9 null modem cable. During the development you need to use minicom to install Linux kernel, format filesystem and configure device.


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