Raspberry Pi Zero W has no 5GHz Wi-Fi (only 2.4GHz), and a somewhat weak processor. It does not support using a large amount of Octoprint-plugins or streaming of video and is not officially recommended by the OctoPrint project. Use more powerful models like the 3B+ or the latest RPI 4 to take full advantage of Octoprint. However, they do need to be connected by USB, plus they need a separate PSU, which results in a less clean setup.
In this article, we will outline the preparations and configurations necessary to outfit your MK3S with Octoprint using a Raspberry Pi Zero. Here we will go through how to solder the correct GPIO pins and connecting the Raspberry Pi to the printer.
PRUSAPRINT (PRUSA'S CUSTOM OCTOPRINT IMAGE) IS NOW OUTDATED AND NO LONGER BEING MAINTAINED! This solution has been superseded by PrusaLink and Prusa Connect. If you wish to use Octoprint, we recommend following the guide to creating your own Octoprint image.
You can run Octoprint from most versions of the Raspberry Pi (Zero, 2, 3, 3B, etc.), but this is covered in a different article. We have chosen the Raspberry Pi Zero W for this tutorial, as it integrates neatly with the MK3s Einsy RAMBo with no need for an external power supply.
This guide is not covering any other fruit alternatives, like Banana Pi, Orange Pi, etc.
Distinguish between models Pi Zero W and Pi Zero. The letter "W" stands for Wireless. Buying a cheaper Pi Zero without WiFi will not work with this guide!
Parts and preparations
To complete this guide you need the following components:
Raspberry Pi Zero W
2x20-pin Strip Dual Male Header, with 18 mm pins.
Micro SD card of at least 8GB (16 GB is recommended).
To create a connection between RPi Zero W and EINSY board you need a GPIO header which you solder to the RPi board. You need a break-away 2x20-pin Strip Dual Male Header, the version with 18 mm pins. These types of headers come in different versions, but the crucial part is that they are 18 mm long.
2x20-pin Strip Dual Male Header
Now that you have your Pi and the pins, they need to be installed to the Einsy Rambo. To ensure the correct position of pins and optimal distance, our developers created a printed part, the RPi Zero Frame, which is placed between RPi Zero and EINSY board. This is also used as a template when soldering the pins, ensuring they go where they should.
RPi Zero Frame
RPi Zero Frame can be downloaded here. Recommended settings for print are profile 0.2 SPEED and material PETG or ABS.
The RPi Zero Frame is not fully compatible with the RPi Zero 2 layout. Be careful if using it or seek out a remix.
Soldering the GPIO pins
Certain parts of this guide require the usage of soldering and cutting tools. Please read carefully the instructions for such devices/tools and use personal protective equipment. Prusa Research does not assume responsibility, and expressly disclaim liability for loss, injuries, or damage.
Prepare a piece of the GPIO-header, as in the illustration above, by simply breaking off the length you need and pulling out the pins you do not need with some pliers (right picture).
We are connecting this header to the UART pins (5V, GND, TXD, RXD) for serial communication, and to GPIO22 as mechanical support.
Sandwich the printed frame, the RPi Zero, and the GPIO pins together like is shown in the right picture below, Make sure the tips of the GPIO pins stick out about 1 mm, from the correct holes. You are now ready to solder the pins.
When soldering, you need the solder to "flow", creating a proper bond between the pins and the pads on the RPi Zero. If you end up with balls and blobs you need to reflow it for a proper bond. The solder needs to be clinging to the pins and the pads. You want "cones" as in the pictures above and below. Most solder will also turn shiny if done correctly. If you have no experience soldering we recommend looking up some videos on the basics.
Installation of SD card
The RPi Zero W hardware is now ready to be installed to the Rambo case, but for the lack of access once installed, you first need to prepare the SD-card which runs its operating system.
PRUSAPRINT (PRUSA'S CUSTOM OCTOPRINT IMAGE) IS NOW OUTDATED AND NO LONGER BEING MAINTAINED! This solution has been superseded by PrusaLink and Prusa Connect. If you wish to use Octoprint, we recommend following the guide to creating your own Octoprint image.
Connecting the RPi Zero to your printer
Make sure the printer is turned off and carefully cut all the indicated plastic parts and remove the cut-out part. During the cutting process, MAKE SURE YOU DON'T CUT the Einsy board!!!
On the MK3 (non S) there might not be this prepared area to cut. You can still cut it out, but this is a bit scary and you won't have the protective cover. We recommend printing the latest version of the Rambo-case.
Slot the RPi Zero, with its frame, into the connector holes indicated below (green square). Then fit the cover to protect the RPi Zero W (purple arrows).
Make sure the RPi Zero is properly installed by inspecting the connector on the other side of the Einsy Rambo (green arrows). Notice that the position of the support pin is in the corner (purple arrow).
Checking if the RPi works
Go to the printer's LCD menu -> Settings -> RPi port, and make sure it is set to ON. Return to the printer's home screen. Now, wait for a few minutes. The RPi Zero is not a superfast computer and it needs time to boot.
Then open the browser and try opening a website: octopi.local. If octopi.local doesn't work, please use the following steps: Check your router for a new IP address, using an app like Fing, or wait until the address is displayed on the printer's display.
As soon as you have the IP, open a web browser on your PC, type it in, and hit Enter. If the Octoprint webpage loads, you can continue.
Troubleshooting
OctoPrint provided by Prusa Research is tested and is confirmed to be booting correctly. If you can't access the web interface, check the following:
Is the RPi port enabled on your printer?
Did you enter the correct Wi-Fi name (SSID) and password?
Is the RPi Zero W correctly plugged in the EINSY RAMBo board?
