This Instructable will describe the steps to run Octoprint on your Ultimaker original.
I'm running a Mac, so this will have the steps described to from a OSx point of view :)
First of all, you will need to have the right 'software' running on your RaspberryPi. Let's see how to do that!
Step 1: Baking the Pi With the Right Ingredients
The easiest way to install Octoprint is to put the precompiled version :) on your SD card. Download the latest version and unzip it. (This is a big file, so take your time).
Now, for Mac users, a very handy tool to put the .img file (that you've just unzipped) onto your SD card in a way it will work is to use the ApplePi Baker.
Ok, it sounds strange to restore something that is not damaged, but to put your image on the SD card, you will need to go to the IMG Recipe, browse for your unzipped IMG file and click 'Restore Backup'. (My IMG did not show up when I was looking in my 'downloads folder' where I unzipped it, so I copied the IMG file to my Desktop). This will take a couple of minutes, so grab a drink during the baking process :)
Step 2: Starting Up Your Raspberry for the First Time (aka First Boot)
There are some sites that I used during this setup. The RepRap OctoPrint page is a usefull resource, it only did not tell me to take the following step:
Insert your MicroSD card into your RaspberryPi, hook up a HDMI screen (I first attempted to use a HDMI to VGA converter to hook up an 'old' screen, but that turned out not to work...), a keyboard and a mouse.
Decide whether you would want to connect your Raspberry with an ethernet cable or a wifi dongle. Connect one of them as well.
Now power your RaspberryPi!
It will start up, showing a black screen with a lot of text running :)
After succesfully booting, you will have some options. I choose to expand the filesystem by pressing enter on 1. Changed the user password on 2. Press finish (go there with the arrow keys), the RaspberryPi will reboot and it will show you something that starts to look like a real screen like you're used to on a regular computer. (Pretty usefull tips in the Add Wifi to Your 3D Printer Instructable
After rebooting, connect to the internet by choosing the right network (press scan first to get the full list of available networks).
You can now disconnect from the screen and keyboard and move your Raspberry to your Ultimaker :)
Step 3: Connecting Your Ultimaker to the Raspberry Pi and Running Octoprint
Ok, so we've prepared our RaspberryPi with a build that contains Octoprint, we have connected to the internet and have had a cup of coffee to prepare for the final part!
Make sure your Ultimaker is loaded with default firmware! (I could not connect since there was some experimental firmware running on it from a previous hackaton...)
Connect your printer with the printer cable to an usb slot on your RaspberryPi. Power up your Pi.
Within your browser go to octopi.local (remember, I'm on OSx!, when you're running on Windows, make sure to know what the IP address of your Pi is and enter that number in your browser).
When connecting for the first time, OctoPi asks you whether you want to add a username and a password for your printer on OctoPi. I did.
My first attempt to connect was not succesfull because of firmware issues, so upload new firmware if the connection to the printer does not run smooth.
Log in to Octoprint with the username and password you just entered and connect to the printer. When it's your lucky day it will connect with the AUTO detection modes on. Otherwise try another baudrate and serial port.
Step 4: Print Using OctoPrint
Once you are connected to your printer, you can start controlling your printer using the Temperature and Control tab. Enter a temperature and you will notice your printer starts to heat up :)
Once warmed up you can manually control your printer from the Control tab. Remove your filament by pressing the Retract button (after you have entered 400 mm under Tool E). When you think your printer retracts too slow for your impatient mind, head over to the Settings and change the speed of E within the Printer Parameters :)
Now upload a gcode file. For my first print I just had to print an Octopus...
Upload your gcode and simply press Print when it has finished uploading!
Watch your printer and smile :D