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octoson - an introduction

octoson = OctoPrint + Intel Edison

The Intel Edison using the mini-breakout board has a convenient form factor which makes it very suitable for integration in the body of a 3D printer and run OctoPrint to control it.

This project is about doing such a build, both hardware and software for a Printrbot Play.

Status

As of 2018-04-25:

  • the software side using the manual install is working, but has not been tested in a long time as the focus has shifted to building w/ Yocto.
  • the Edison powered via a separate wall-wart via a soldered barrel jack is working.
  • the enclosure has been designed using FreeCAD (see below).

Hardware

The end goal is to have the Edison connected to the Play serial port using USB host, with a 3D printed case held to the printer chassis using magnets. Power- wise, we will investigate both solutions of having the Edison using a dedicated power supply or the printer one.

Enclosure

I have designed an enclosure for the mini breakout board using FreeCAD. It can be found either on Thingiverse or YouMagine. It used magnets to hold onto the Play body.

Power requirements

It is mandatory to use the external power to have USB host working, one cannot power the Edison via USB. I am currently using a barrel jack soldered to the Edison mini breakout board to power the Edison module (took it from an Arduino board I had).

The other solution is to reuse the Play power supply, by plugging into the hotend connector but I still need to assess if the normal Play power brick has enough room for it (I am not using a heated bed but also do not want to switch to a bulky ATX power supply).

Enabling USB host

Currently, I am using a standard phone USB host adapter which I chose for its compactness. The next step is to build a sleeker adapter by rewiring USB cables.

Software

There are two ways to do it here: either manually install OctoPrint on the Edison normal Linux image or create an image from scratch using Yocto.

Manual install (deprecated)

Follow these steps to perform the installation. Note that these have not been used in a long time and might not work (which is why I am deprecating them)

  1. Flash Edison official image, downloaded from the Intel website. I am using iot-devkit-prof-dev-image-edison-20160606-patch.zip.
  2. configure_edison –setup
  3. useradd -d /home/octoson -m -U -G dialout octoson
  4. git clone https://github.com/foosel/octoprint octoprint.git
  5. python setup.py install
  6. create /lib/systemd/system/octoprint.service
  7. systemctl enable octoprint && systemctl start octoprint
  8. connect to 192.168.1.165:5000 and follow OctoPrint setup wizard
  9. systemctl disable ofono|clloader|wyliodrin|etc to remove unused services from boot sequence and system memory.
  10. add octoson.sudo to /etc/sudoers.d so that the OctoPrint UI can perform administative tasks like restarting the OctoPrint server or the system itself.

Using Yocto to rebuild an image

This is the cleaner solution, so that the image can be tailored to OctoPrint, with the unwanted parts removed.

It used to be stuck on several issues:

  1. The Edison Yocto image is old and based on the Yocto daisy branch. This means it is not possible to use the latest version of certain packages because they depend on a newer version of the poky repository. An example of this is the existing meta-maker layer which depends on meta-openembedded. Even using the daisy branch of meta-openembedded and meta-maker leads to errors, cf my question on openembedded-devel about the problem.
  2. The Edison Yocto image does not appear to be maintained anymore. Some links in the recipes archives have changed and now break. Some fixes need to be manually applied to the Bitbake recipes as a result.

Fortunately, the community is maintaining the edison tree and has rebased it to work over recent versions of Yocto. In particular, Ferry Toth maintains a fully functional meta-intel-edison here. This is the solution I am using.

Credits

  • Ferry Toth for maintaining the new meta-intel-edison layer that allows Edison to have a currently working Yocto distro.
  • logxen github gist for the first draft of the manual installation instructions and showing me it was possible to do.
  • the meta-maker Yocto maintainers for the nice packaging bits and making all the hard integration work.

TODOs

  • Add reference to barrel jack part.
  • Add pictures of the installed setup.
  • Add more links to various sources.
  • Make Yocto image build work.
  • More testing, esp w.r.t bootup time and init order (it currently seems that if the Edison boots with the printer plugged in, it can misdetect it).