picocom

As its name suggests, picocom is a minimal dumb-terminal emulation program. It is, in principle, very much like minicom (1), only it's "pico" instead of "mini"! It was designed to serve as a simple, manual, modem configuration, testing, and debugging tool. It has also served (quite well) as a low-tech "terminal-window" to allow operator intervention in PPP connection scripts (something like the ms-windows "open terminal window before / after dialing" feature). It could also prove useful in many other similar tasks.

When picocom starts it opens the terminal (serial device) given as its non-option argument. Unless the --noinit option is given, it configures the device to the settings specified by the option-arguments (or to some default settings), and sets it to "raw" mode. If --noinit is given, the initialization and configuration is skipped; the device is just opened. Following this, picocom sets the standard-input and standard-output to raw mode. Having done so, it goes in a loop where it listens for input from stdin, or from the serial port. Input from the serial port is copied to the standard output while input from the standard input is copied to the serial port. picocom also scans its input stream for a user-specified control character, called the "escape character" (being by default "C-a"). If the escape character is seen, then instead of sending it to the serial-device, the program enters "command mode" and waits for the next character (which is called the "function character"). Depending on the value of the function character, picocom performs one of the operations described in the "Commands" section below.

[escape character] : Do nothing, remain in command mode. This means that if the escape character ("C-a", by default) is typed more than once, the program still remains in command-mode waiting for the function character.

C-x : Exit the program: if the "--noreset" option was not given then the serial port is reset to its original settings before exiting; if it was given the serial port is not reset.

C-q : Quit the program *without* reseting the serial port, regardless of the "--noreset" option.

C-p : Pulse the DTR line. Lower it for 1 sec, and then raise it again.

C-t : Toggle the DTR line. If DTR is up, then lower it. If it is down, then raise it.

B-u : Baud up. Increase the baud-rate.

B-d : Baud down. Decrease the baud-rate.

C-f : Cycle through flow-control settings.

C-y : Cycle through parity settings.

C-b : Cycle through databits-number settings.

C-v : Show program options (like baud rate, data bits, etc). Only the options that can be modified online (through commands) are shown, not those that can only be set at the command-line.

C-s : Send (upload) a file (see "Sending and Receiving Files" below)

C-r : Receive (download) a file (see "Sending and Receiving Files" below)

After performing one of the above operations (except for the one binded to the [escape] function character) the program leaves the command mode. Example: To increase the baud-rate by two steps, you have to type:

C-a, C-u, C-a, C-u

assuming of-course that "C-a" is the escape character.

picocom can send and receive files over the serial port using external programs that implement the respective protocols. In Linux typical programs for this purpose are:

rx(1) -- receive using the X-MODEM protocol

rb(1) -- receive using the Y-MODEM protocol

rz(1) -- receive using the Z-MODEM protocol

sx(1) -- send using the X-MODEM protocol

sb(1) -- send using the Y-MODEM protocol

sz(1) -- send using the Z-MODEM protocol

ascii-xfr(1) -- receive or transmit ASCII files

The name of, and the command-line options to, the program to be used for transmitting files is given by the "--send-cmd" option. Similarly the program to receive files, and its argumets, are given by the "--receive-cmd" option. For example, in order to start a picocom session that uses "sz" to transmit files, and "rz" to receive, you have to say something like this:

picocom --send-cmd "sz -vv" --receive-cmd "rz -vv"

During the picocom session, if you key the "send" or "receive" commands (e.g. by pressing C-a, C-s, or C-a, C-r) you will be prompted for a filename. At this prompt you can enter one or more file-names, and any additional arguments to the transmission or reception program. After that, picocom will start the the external program as specified by the "--send-cmd", or "--receive-cmd" option, and with any filenames and additional arguments you may have supplied. The standard input and output of the external program will be connected to the serial port. The standard error of the external program will be connected to the terminal which---while the program is running---will revert to canonical mode. Pressing 'C-c' while the external program is running will prematurely terminate it, and return control to picocom. Pressing 'C-c' at any other time, has no special effect; the character is normally passed to the serial port.

--baud | -b

--flow | -f

--parity | -p

--databits | -d

--esacpe | -e

--noinit | -i

--noreset | -r

--send-cmd | -s

--receive-cmd | -v

--help | -h

picocom was written by Nick Patavalis (npat@efault.net)

The latest version of "picocom" can be downloaded from: http://efault.net/npat/hacks/picocom/

This man page was written using xmltoman by Oliver Kurth for Debian.