Service configuration

As it was mentioned in the project presentation chapter (Project Structure), Libre-Printer relies on a service that manages the data coming from the interface.

The behavior of this service is configurable in a single file centralizing commands that are considered useful for the RetroPrinter project.

Please note that the configuration of the ESC/P2 converter is always done through separate files identical to the original project. Although this is noted on the list of things to fix one day.

The configuration file is libreprinter.conf. It is currently split into 3 sections:

• misc (miscellaneous settings): Settings that apply to the whole service; Defines folders, paths to conversion binaries, type of protocol to decode, etc.

• parallel_printer: Interface configuration parameters in case a printer using the Parallel/Centronics standard is connected. This is the default setting.

• serial_printer: Interface configuration parameters in case a printer using the Serial/RS-232 standard is connected. This situation is disabled by default.

[misc]

• start_cleanup=no

  Reset directories in output_path, and shared memory during startup.

• escp2_converter_path=/usr/bin/convert-escp2

  Path of espc2 converter. If the binary is not at the end of the given path its expected name is “convert-escp2”.

  • For the RetroPrinter image: /home/pi/temp/sdl/escparser/convert-escp2

  • For the LibrePrinter Debian package: /usr/bin/convert-escp2

• pcl_converter_path=/usr/local/bin/gpcl6

  Path of the GhostPCL binary used to convert HP PCL files with ghostscript

• endlesstext=no

  Equivalent of simple_spool legacy config. Possible values & behaviors:

  plain-stream	text stream
  strip-escp2-stream	remove escp2 commands stream
  plain-jobs	text job
  strip-escp2-jobs	remove escp2 commands job
  no	waits for the pages one after the other

  If plain-stream or strip-escp2-stream, output_printer option will be disabled.

• line_ending=unix

  Used to convert line endings in plain-stream/plain-jobs conversion modes; equivalent of linefeed_ending legacy config. Possible values: unix/windows

• usb_passthrough=no

  Raw peripheral path. If different from “no”, data will be stored in raw files and then directly written on this peripheral (which will be considered as a file opened in write mode) without further processing. Possible values: “no” or any path even a printer path like “/dev/usb/lp0”.

  WARNING: In this last example be warned that output_printer setting is NOT disabled. It should be noted that any “raw” parallel interface like /dev/usb/lp* disappears when Cups is used on it. Thus it can’t be used with this functionality anymore. TL;DR: Do not use the path of a printer whose name you have entered in output_printer.

• output_printer=no

  Cups printer name. If different of “no”, put the name of a printer installed and configured in Cups. The list of printers is given by the command “lpstat -p -d”. Data will be converted in pdf and redirected to the printer.

• serial_port=/dev/ttyACM0

  Serial port on which the interface is connected.

• output_path=

  Path where /raw /pdf /pcl /txt-jobs /txt-stream directories are created. Default: current directory or /var/lib/libre-printer/ for the Debian package.

• end_page_timeout=2

  Time elapsed without receiving data corresponding to the interpretation of an end of page. In seconds and > 0.

• emulation=epson

  Emulation used.

  epson or escp2	For Epson ESC/P and ESC/P2 data (default)
  hp or pcl	For HP PCL data
  text	For raw text data from the printer (equivalent of epson + plain-jobs)
  auto	(Not implemented)

[parallel_printer]

• delayprinter=0

  Slow down receiving from computer in micro seconds.

[serial_printer]

• enabled=no

  Enable/disable the serial printer interface. Possible values:

  • no: Only parallel printer will be working;

  • yes: Only serial printer will be working.

  • auto: Let the interface choose the serial printer if it is active during its boot process (Not implemented).

• dtr_logic=high

  DTR config:

  • high: printer is ready when DSR is asserted (space high level) (default)

  • low: printer is ready when DSR is deasserted (mark low level) (CP2102)

• baudrate=19200

  Serial speed. Set it to the computer value. (Usually not above 19200.)

• flow_control=hardware

  Serial flow control Possible values:

  • hardware: Flow is controlled with DTR (printer)/DSR(computer) pins (default)

  • software: Flow is controlled with XON/XOFF bytes

  • both: Flow is controlled by both methods: hardware + software