greenarrow / austerusG

austerusG is a collection of programs for controlling 3D printers like the Ultimaker on Linux in a simple and efficient manner.

austerusG

austerusG is a collection of programs for controlling 3D printers like RepRap and the Ultimaker on Linux in a simple and efficient manner.

Why another host?

• Many previous host programs have issues with latency that lead to printer pauses and ultimately physical defects on prints. Languages like Java and Python are inherently unpredictable due to the use of garbage collectors etc.

• austerusG has been designed to stream gcode to printers with the lowest latency and smallest overhead possible to ensure the highest quality of prints. This allows the use of very low power hardware such as the Raspberry Pi.

Introduction

$ make
# make install
$ austerus-panel -s /dev/ttyACM0 -b 230400
$ austerus-send -s /dev/ttyACM0 -b 230400 -a 6 test.gcode

Design

austerusG is written entirely in C and consists of several small purposeful programs.

When austerus-send is executed it in turn starts an austerus-core process that it talks to through a pipe.

|file| =====> |austerus-send| =====> |austerus-core| =======> |printer|
        read                   pipe                   serial

austerus-core

This is the most important part of austerusG. The core is kept as simple as possible to ensure the lowest possible latency.

The core simply reads lines in from stdin and writes them out as fast as the printer accepts them.

Critically there are two places where the program blocks:

• Read from stdin
  • The use of the pipe ensures this never happens while there is still data to send.
• Read from serial while unacknowledged lines > ack-count
  • Where unacknowledged lines is the number of lines that have been sent to the printer that acknowledgements have not been recieved for.
  • Where limit is the number of lines the printer firmware can queue.

The code paths between blocking points and transmission of the next line are very short so it would be unusual for the line queue on the firmware to not be full.

On POSIX systems you can build austerus-core as a setuid binary that will raise the priority of its own process. This can be a good idea if running on low power hardware that has other processes running.

$ make SETUID=1
# make SETUID=1 install

austerus-send

Simple program for printing gcode files while displaying progress.

austerus-panel

Simple Ncurses based control panel for 3D printers.

austerus-verge

Output the region of the print bed that will be used when printing a gcode file.